阅读说明：本技术 电容检测电路和触控芯片 (Capacitance detection circuit and touch chip ) 是由 袁广凯 于 2020-07-21 设计创作，主要内容包括：本申请提供一种电容检测电路,能够降低屏幕噪声对电容检测的影响。该电容检测电路包括：驱动电路,与第一通道和屏幕中的第二通道相连,用于使第一通道和第二通道进行充放电；抵消电路,包括与第一通道相连的抵消电容,用于抵消第一通道的基础电容；释放电路,与第二通道相连,用于释放第二通道上的电荷以抵消第二通道的自电容,使得第二通道的电容信号中仅包括来自屏幕的噪声信号；放大电路,分别与第一通道和第二通道相连,用于接收第一通道的电容信号和第二通道的电容信号,并根据第一通道的电容信号和第二通道的电容信号输出电压信号,其中,电压信号用于确定抵消噪声信号后的第一通道的自电容相对于基础电容的电容变化量。(The application provides a capacitance detection circuit, can reduce the influence of screen noise to capacitance detection. The capacitance detection circuit includes: the driving circuit is connected with the first channel and a second channel in the screen and used for charging and discharging the first channel and the second channel; the offset circuit comprises an offset capacitor connected with the first channel and used for offsetting the basic capacitor of the first channel; the releasing circuit is connected with the second channel and used for releasing the charges on the second channel to offset the self-capacitance of the second channel, so that only the noise signal from the screen is included in the capacitance signal of the second channel; and the amplifying circuit is respectively connected with the first channel and the second channel and used for receiving the capacitance signal of the first channel and the capacitance signal of the second channel and outputting a voltage signal according to the capacitance signal of the first channel and the capacitance signal of the second channel, wherein the voltage signal is used for determining the capacitance variation of the self-capacitance of the first channel relative to the basic capacitance after the noise signal is cancelled.)

1. A capacitance detection circuit for detecting a self-capacitance of a first channel in a screen, the capacitance detection circuit comprising:

the driving circuit is connected with the first channel and a second channel in the screen and used for charging and discharging the first channel and the second channel;

the offset circuit comprises an offset capacitor, the offset capacitor is connected with the first channel, and the offset capacitor is used for offsetting the basic capacitor of the first channel;

the releasing circuit is connected with the second channel and used for releasing the charge on the second channel to offset the self-capacitance of the second channel, so that only the noise signal from the screen is included in the capacitance signal of the second channel;

the amplifying circuit is used for receiving the capacitance signal of the first channel and the capacitance signal of the second channel and outputting a voltage signal according to the capacitance signal of the first channel and the capacitance signal of the second channel, wherein the voltage signal is used for determining the capacitance variation of the self-capacitance of the first channel relative to the basic capacitance after the noise signal is cancelled.

2. The capacitance detection circuit according to claim 1, further comprising:

the compensation circuit comprises a compensation capacitor equal to the offset capacitor, and the compensation capacitor is connected with the second channel;

the release circuit is also connected with the compensation capacitor and used for charging and discharging the compensation capacitor.

3. The capacitance detection circuit of claim 2, wherein one detection cycle of the capacitance detection circuit comprises a first phase, a second phase, and a third phase, wherein:

in the first stage, the driving circuit charges or discharges the first channel and the second channel, the offset circuit charges or discharges the offset capacitor, and the release circuit charges the compensation capacitor to a preset voltage;

in the second stage, charge transfer is carried out between the first channel and the counteracting capacitor so as to counteract the basic capacitor of the first channel through the counteracting capacitor, and the release circuit pulls the voltage of the second channel to the preset voltage;

in the third stage, the first channel and the second channel input capacitance signals to the amplifying circuit, and the amplifying circuit outputs voltage signals according to the capacitance signals of the first channel and the second channel.

4. The capacitance detection circuit according to claim 3, wherein the predetermined voltage is a common mode voltage of the input terminals of the amplifying circuit, and/or wherein the predetermined voltage is equal to one half of a supply voltage.

5. The capacitance detection circuit according to claim 3 or 4, wherein the drive circuit comprises a first switch and a second switch,

one end of the first channel is connected to a power supply voltage through the first switch and is connected to one input end of the amplifying circuit through a third switch, the other end of the first channel is connected to the ground,

one end of the second channel is connected to a power supply voltage through the second switch, and is connected to the other input end of the amplifying circuit through a fourth switch, and the other end of the second channel is connected to the ground.

6. The capacitance detection circuit according to claim 5, wherein the release circuit comprises a fifth switch and a sixth switch, one end of the compensation capacitor is connected to a preset voltage through the fifth switch and is connected to the second channel through the sixth switch, and the other end of the compensation capacitor is grounded.

7. The capacitance detection circuit according to claim 6, wherein the cancellation circuit comprises a seventh switch and an eighth switch, one end of the cancellation capacitor is connected to ground through the seventh switch, and is connected to the first channel through the eighth switch, and the other end of the cancellation capacitor is connected to ground.

8. The capacitance detection circuit according to claim 7,

in the first stage, the first switch, the second switch, the fifth switch, and the seventh switch are closed, wherein the first channel and the second channel are charged to a power supply voltage, the cancellation capacitor is discharged to 0, and the compensation capacitor is charged to a preset voltage;

in the second stage, the fifth switch, the sixth switch and the eighth switch are closed, wherein the first channel discharges to the cancellation capacitor, and the voltage of the second channel is pulled to the preset voltage;

in the third phase, the third switch, the fourth switch, the sixth switch, and the eighth switch are closed, wherein the first channel and the second channel discharge to the amplification circuit.

9. The capacitance detection circuit according to claim 8, wherein the drive circuit further includes a ninth switch and a tenth switch,

one end of the first channel is connected to ground through the ninth switch, one end of the second channel is connected to ground through the tenth switch,

the cancellation circuit further comprises an eleventh switch, and one end of the cancellation capacitor is connected to a power supply voltage through the eleventh switch.

10. The capacitance detection circuit of claim 9, wherein the detection cycle further comprises a fourth phase, a fifth phase, and a sixth phase, wherein:

in the fourth stage, the fifth switch, the ninth switch, the tenth switch and the eleventh switch are closed, wherein the first channel and the second channel are discharged to 0, the cancellation capacitor is charged to a power supply voltage, and the compensation capacitor is charged to a preset voltage;

in the fifth phase, the fifth switch, the sixth switch and the eighth switch are closed, wherein the cancellation capacitor discharges to the first channel, and the voltage of the second channel is pulled to the preset voltage;

in the sixth phase, the third switch, the fourth switch, the sixth switch, and the eighth switch are closed, wherein the amplification circuit discharges to the first channel and the second channel;

wherein the capacitance variation of the self-capacitance of the first channel with respect to the base capacitance is determined according to the voltage signals output by the amplifying circuit in the third stage and the sixth stage.

11. The capacitance detection circuit of any one of claims 7-10, wherein the cancellation capacitance is equal to a base capacitance of the first channel.

12. The capacitance detection circuit according to claim 6, wherein the cancellation circuit comprises a seventh switch, an eighth switch, a twelfth switch and a thirteenth switch, one end of the cancellation capacitor is connected to ground through the seventh switch and is connected to the first channel through the eighth switch, and the other end of the cancellation capacitor is connected to a power supply voltage and ground through the twelfth switch and the thirteenth switch, respectively.

13. The capacitance detection circuit according to claim 12,

in the first stage, the first switch, the second switch, the fifth switch, the seventh switch and the twelfth switch are closed, wherein the first channel and the second channel are charged to a power supply voltage, the voltage of an upper plate of the offset capacitor is 0, the voltage of a lower plate of the offset capacitor is the power supply voltage, and the compensation capacitor is charged to a preset voltage;

in the second stage, the fifth switch, the sixth switch, the eighth switch and the thirteenth switch are closed, wherein the voltage of the upper plate of the cancellation capacitor is a negative power voltage and the voltage of the lower plate is 0, the first channel discharges to the cancellation capacitor, and the voltage of the second channel is pulled to the preset voltage;

in the third phase, the third switch, the fourth switch, the sixth switch, the eighth switch, and the thirteenth switch are closed, wherein the first channel and the second channel discharge to the amplification circuit.

14. The capacitance detection circuit according to claim 13,

the driving circuit further includes a ninth switch through which one end of the first channel is connected to ground, and a tenth switch through which one end of the second channel is connected to ground,

the cancellation circuit further comprises an eleventh switch, and one end of the cancellation capacitor is connected to a power supply voltage through the eleventh switch.

15. The capacitance sensing circuit of claim 14, wherein the sensing cycle further comprises a fourth phase, a fifth phase, and a sixth phase, wherein:

in the fourth phase, the fifth switch, the ninth switch, the tenth switch, the eleventh switch and the thirteenth switch are closed, wherein the first channel and the second channel are discharged to 0, the cancellation capacitor is charged to a power supply voltage, and the compensation capacitor is charged to a preset voltage;

in a fifth phase, the fifth switch, the sixth switch, the eighth switch and the twelfth switch are closed, wherein the cancellation capacitor discharges to the first channel, and the second channel charges to the preset voltage;

in the sixth phase, the third switch, the fourth switch, the sixth switch, the eighth switch, and the twelfth switch are closed, wherein the amplification circuit discharges to the first channel and the second channel.

16. The capacitance detection circuit of any one of claims 12-15, wherein the cancellation capacitance is equal to one third of a base capacitance of the first channel.

17. The capacitance detection circuit according to any one of claims 1 to 4, wherein the screen includes a plurality of lateral channels and a plurality of longitudinal channels, wherein the self-capacitance of the first channel of the plurality of lateral channels and the self-capacitance of the first channel of the plurality of longitudinal channels are detected in parallel in each detection cycle.

18. The capacitance detection circuit according to claim 17, wherein when detecting an odd number of the horizontal channels or the vertical channels, the remaining even number of channels except the first channel are detected, and then the remaining even number of channels except the last channel are detected.

19. The capacitance detection circuit according to claim 17, wherein when detecting even number of the lateral channels or the longitudinal channels, an odd number of the channels is first used as the first channel and an even number of the channels is used as the second channel, and then an even number of the channels is used as the first channel and an odd number of the channels is used as the second channel.

20. A touch chip comprising the capacitance detection circuit according to any one of claims 1 to 19.

Technical Field

The embodiment of the application relates to the field of capacitance detection, and more particularly relates to a capacitance detection circuit and a touch chip.

Background

Capacitive sensors are widely used in electronic products to implement touch detection. When a conductor such as a finger approaches or touches the detection electrode, the capacitance corresponding to the detection electrode changes, and by detecting the change amount of the capacitance, the information that the finger approaches or touches the detection electrode can be acquired, so as to determine the operation of the user. However, noise generated on the screen of the electronic device affects the detection result. Therefore, how to reduce the influence of the screen noise on the capacitance detection becomes an urgent problem to be solved.

Disclosure of Invention

The embodiment of the application provides a capacitance detection circuit and a touch chip, which can reduce the influence of screen noise on capacitance detection.

In a first aspect, a capacitance detection circuit is provided for detecting a self-capacitance of a first channel in a screen, the capacitance detection circuit including:

the driving circuit is connected with the first channel and a second channel in the screen and used for charging and discharging the first channel and the second channel;

the offset circuit comprises an offset capacitor, the offset capacitor is connected with the first channel, and the offset capacitor is used for offsetting the basic capacitor of the first channel;

the releasing circuit is connected with the second channel and used for releasing the charge on the second channel to offset the self-capacitance of the second channel, so that only the noise signal from the screen is included in the capacitance signal of the second channel;

the amplifying circuit is used for receiving the capacitance signal of the first channel and the capacitance signal of the second channel and outputting a voltage signal according to the capacitance signal of the first channel and the capacitance signal of the second channel, wherein the voltage signal is used for determining the capacitance variation of the self-capacitance of the first channel relative to the basic capacitance after the noise signal is cancelled.

In a possible implementation manner, the capacitance detection circuit further includes a compensation circuit, the step length circuit includes a compensation capacitor equal to the cancellation capacitor, and the compensation capacitor is connected to the second channel; the release circuit is also connected with the compensation capacitor and used for charging and discharging the compensation capacitor.

In one possible implementation, one detection cycle of the capacitance detection circuit includes a first phase, a second phase, and a third phase, where:

in the first stage, the driving circuit charges or discharges the first channel and the second channel, the offset circuit charges or discharges the offset capacitor, and the release circuit charges the compensation capacitor to a preset voltage;

in the second stage, charge transfer is carried out between the first channel and the counteracting capacitor so as to counteract the basic capacitor of the first channel through the counteracting capacitor, and the release circuit pulls the voltage of the second channel to the preset voltage;

in the third stage, the first channel and the second channel input capacitance signals to the amplifying circuit, and the amplifying circuit outputs voltage signals according to the capacitance signals of the first channel and the second channel.

In a possible implementation manner, the preset voltage is a common-mode voltage of the input terminal of the amplifying circuit, and/or the preset voltage is equal to one half of the power supply voltage.

In one possible implementation, the driving circuit includes a first switch and a second switch, one end of the first channel is connected to a power supply voltage through the first switch and is connected to one input terminal of the amplifying circuit through a third switch, the other end of the first channel is connected to ground, one end of the second channel is connected to the power supply voltage through the second switch and is connected to the other input terminal of the amplifying circuit through a fourth switch, and the other end of the second channel is connected to ground.

In a possible implementation manner, the release circuit includes a fifth switch and a sixth switch, one end of the compensation capacitor is connected to a preset voltage through the fifth switch, and is connected to the second channel through the sixth switch, and the other end of the compensation capacitor is grounded.

In one possible implementation manner, the cancellation circuit includes a seventh switch and an eighth switch, one end of the cancellation capacitor is connected to ground through the seventh switch, and is connected to the first channel through the eighth switch, and the other end of the cancellation capacitor is connected to ground.

In a possible implementation manner, in the first stage, the first switch, the second switch, the fifth switch, and the seventh switch are closed, where the first channel and the second channel are charged to a power supply voltage, the cancellation capacitor is discharged to 0, and the compensation capacitor is charged to a preset voltage; in the second stage, the fifth switch, the sixth switch and the eighth switch are closed, wherein the first channel discharges to the cancellation capacitor, and the voltage of the second channel is pulled to the preset voltage; in the third phase, the third switch, the fourth switch, the sixth switch, and the eighth switch are closed, wherein the first channel and the second channel discharge to the amplification circuit.

In one possible implementation manner, the driving circuit further includes a ninth switch and a tenth switch, one end of the first channel is connected to ground through the ninth switch, one end of the second channel is connected to ground through the tenth switch, and the cancellation circuit further includes an eleventh switch, and one end of the cancellation capacitor is connected to a power supply voltage through the eleventh switch.

In one possible implementation, the detection cycle further includes a fourth phase, a fifth phase, and a sixth phase, where:

in the fourth stage, the fifth switch, the ninth switch, the tenth switch and the eleventh switch are closed, wherein the first channel and the second channel are discharged to 0, the cancellation capacitor is charged to a power supply voltage, and the compensation capacitor is charged to a preset voltage;

in the fifth phase, the fifth switch, the sixth switch and the eighth switch are closed, wherein the cancellation capacitor discharges to the first channel, and the voltage of the second channel is pulled to the preset voltage;

in the sixth phase, the third switch, the fourth switch, the sixth switch, and the eighth switch are closed, wherein the amplification circuit discharges to the first channel and the second channel;

wherein the capacitance variation of the self-capacitance of the first channel with respect to the base capacitance is determined according to the voltage signals output by the amplifying circuit in the third stage and the sixth stage.

In one possible implementation, the cancellation capacitance is equal to a base capacitance of the first channel.

In one possible implementation manner, the cancellation circuit includes a seventh switch, an eighth switch, a twelfth switch, and a thirteenth switch, one end of the cancellation capacitor is connected to ground through the seventh switch and is connected to the first channel through the eighth switch, and the other end of the cancellation capacitor is connected to a power supply voltage and ground through the twelfth switch and the thirteenth switch, respectively.

In a possible implementation manner, in the first stage, the first switch, the second switch, the fifth switch, the seventh switch, and the twelfth switch are closed, where the first channel and the second channel are charged to a power supply voltage, the voltage of the upper plate of the cancellation capacitor is 0 and the voltage of the lower plate is the power supply voltage, and the compensation capacitor is charged to a preset voltage; in the second stage, the fifth switch, the sixth switch, the eighth switch and the thirteenth switch are closed, wherein the voltage of the upper plate of the cancellation capacitor is a negative power voltage and the voltage of the lower plate is 0, the first channel discharges to the cancellation capacitor, and the voltage of the second channel is pulled to the preset voltage; in the third phase, the third switch, the fourth switch, the sixth switch, the eighth switch, and the thirteenth switch are closed, wherein the first channel and the second channel discharge to the amplification circuit.

In one possible implementation manner, the driving circuit further includes a ninth switch and a tenth switch, one end of the first channel is connected to ground through the ninth switch, one end of the second channel is connected to ground through the tenth switch, and the cancellation circuit further includes an eleventh switch, and one end of the cancellation capacitor is connected to a power supply voltage through the eleventh switch.

In one possible implementation, the detection cycle further includes a fourth phase, a fifth phase, and a sixth phase, where:

in the fourth phase, the fifth switch, the ninth switch, the tenth switch, the eleventh switch and the thirteenth switch are closed, wherein the first channel and the second channel are discharged to 0, the cancellation capacitor is charged to a power supply voltage, and the compensation capacitor is charged to a preset voltage;

in a fifth phase, the fifth switch, the sixth switch, the eighth switch and the twelfth switch are closed, wherein the cancellation capacitor discharges to the first channel, and the second channel charges to the preset voltage;

in the sixth phase, the third switch, the fourth switch, the sixth switch, the eighth switch, and the twelfth switch are closed, wherein the amplification circuit discharges to the first channel and the second channel.

In one possible implementation, the cancellation capacitance is equal to one third of a base capacitance of the first channel.

In one possible implementation, the screen includes a plurality of transverse channels and a plurality of longitudinal channels, wherein the self-capacitance of the first channel of the plurality of transverse channels and the self-capacitance of the first channel of the plurality of longitudinal channels are detected in parallel in each detection period.

In a possible implementation manner, when detecting odd number of transverse channels or longitudinal channels, the remaining even number of channels except the first channel are detected first, and then the remaining even number of channels except the last channel are detected.

In a possible implementation manner, when detecting even number of transverse channels or longitudinal channels, the odd number of channels is first used as the first channel and the even number of channels is used as the second channel, and then the even number of channels is used as the first channel and the odd number of channels is used as the second channel.

In a second aspect, a touch chip is provided, including: the capacitance detection circuit in the foregoing first aspect and any possible implementation manner of the first aspect.

Based on the technical scheme, the two input ends of the amplifying circuit are respectively connected with the first channel and the second channel, wherein the first channel is a channel to be detected, and the second channel is a noise reference channel. The basic capacitance of the first channel can be offset by the offset circuit, so that the voltage signal output by the amplifying circuit is only related to the variation of the self-capacitance of the first channel relative to the basic capacitance. When the self-capacitance of the first channel is detected, the driving circuit inputs driving signals to the first channel and the second channel, but the charges on the second channel are released through the releasing circuit, so that only noise signals from a screen are included in the capacitance signals input to the amplifying circuit by the second channel. Therefore, after the capacitance signals input into the amplifying circuit by the first channel and the second channel are differentiated in the amplifying circuit, the same noise signals carried in the first channel can be counteracted, so that the voltage signals output by the amplifying circuit can represent the variation of the self-capacitance of the first channel after the noise is counteracted, and the influence of screen noise on capacitance detection is reduced.

Drawings

Fig. 1 is a schematic diagram of the principle of touch detection.

Fig. 2 is a schematic diagram of a capacitance detection circuit according to an embodiment of the present application.

Fig. 3 is a schematic diagram of a capacitance detection circuit according to another embodiment of the present application.

Fig. 4 is a detection timing chart based on the circuit shown in fig. 3.

Fig. 5 is a schematic diagram of one possible implementation based on the circuits shown in fig. 2 and 3.

Fig. 6 is a detection timing chart based on the circuit shown in fig. 5.

Fig. 7 is a schematic diagram of one possible implementation based on the circuits shown in fig. 2 and 3.

Fig. 8 is a detection timing chart based on the circuit shown in fig. 7.

Detailed Description

The technical solution in the present application will be described below with reference to the accompanying drawings.

For a screen of an electronic device, especially a Y-OCTA screen, a display layer of the screen generates large Noise during scanning, and the Noise affects a capacitance detection circuit of a touch layer, so that a Signal Noise Ratio (SNR) obtained by the capacitance detection circuit is low.

Fig. 1 is a schematic diagram of the principle of touch detection. While two layers of channels in the touch layer, both lateral and longitudinal, are shown in fig. 1, capacitive touch systems employing such patterns can typically employ both self and mutual capacitance detection modes. During self-capacitance detection, the touch control chip scans the change condition of the self-capacitance of each transverse channel and each longitudinal channel to the ground. When a finger is close to or touching, the self-capacitance of the channel near the finger becomes large. Such as the lateral channel C shown in FIG. 1, of a finger and its vicinity_RXN-1Will generate a capacitance Cs, a finger and a longitudinal channel C in the vicinity thereof_TX1A capacitance Cd is generated. Because the human body is a conductor and is connected with the ground, the self-capacitance of the channel touched or approached by the finger can be changed, and the touch chip can obtain the touch information of the finger according to the detected change of the self-capacitance.

Therefore, the application provides a capacitance detection circuit which can reduce the influence of screen noise on capacitance detection.

Fig. 2 is a schematic diagram of a capacitance detection circuit according to an embodiment of the present application. The capacitance detection circuit 200 is used to detect a self-capacitance of a first channel in a screen, which is also referred to as a capacitance hereinafter. As shown in fig. 2, the capacitance detection circuit 200 includes a driving circuit 210, a cancellation circuit 220, a release circuit 230, and an amplification circuit 240. Where signal source 300 is used herein to represent screen induced noise.

The driving circuit 210 is connected to the first channel and a second channel in the screen, and is configured to charge and discharge the first channel and the second channel.

The cancellation circuit 220 includes a cancellation capacitor C_CCancellation capacitance C_CConnected to the first channel to cancel the capacitance C_CBasic capacitance C for canceling first channel_X1。

The release circuit 230 is connected to the second channel, and the release circuit 230 is configured to release the charge on the second channel to cancel the self-capacitance of the second channel, so that only the noise signal from the screen is included in the capacitance signal of the second channel;

the amplifying circuit 240 is connected to the first channel and the second channel, respectively, and the amplifying circuit 240 is configured to receive the capacitance signal of the first channel and the capacitance signal of the second channel, and output a voltage signal according to the capacitance signal of the first channel and the capacitance signal of the second channel.

Wherein the voltage signal is used for determining the self-capacitance of the first channel relative to the base capacitance C after the noise signal is cancelled_X1Capacitance variation △ C_X1。

It will be appreciated that the present self-capacitance of the first channel comprises the base capacitance C_X1And a capacitance variation △ C_X1Two parts. Basic capacitor C_X1Always existing, when no finger touches the position corresponding to the first channel, the self-capacitance of the first channel is equal to the basic capacitance C_X1When a finger touches a position corresponding to the first channel, the self-capacitance of the first channel is at the basic capacitance C_X1Based on the capacitance variation △ C_X1Therefore, the capacitance variation △ C can be generated according to whether the first channel generates the capacitance variation △ C_X1To determine whether there is a finger touch.

In this embodiment, two input terminals of the amplifying circuit 240 are respectively connected to a first channel and a second channel, where the first channel is a channel to be detected, and the second channel is a noise reference channel. The basic capacitance C of the first channel can be cancelled by the cancellation circuit 220_X1Therefore, the voltage signal outputted from the amplifying circuit 240 is only equal to the capacitance variation △ C of the first channel_X1In the process of detecting the self-capacitance of the first channel, the driving circuit 210 inputs driving signals to the first channel and the second channel, but the charge on the second channel is released through the releasing circuit 230, so that the capacitance signal of the second channel input amplifying circuit 240 only includes the noise signal from the screen, thus, after the capacitance signals of the first channel and the second channel input amplifying circuit 240 are differentiated in the amplifying circuit 240, the same noise signal carried in the first channel can be cancelled, and the voltage signal output by the amplifying circuit 240 can represent the variation △ C of the self-capacitance of the first channel after the noise is cancelled_X1Thereby reducing the influence of screen noise on the capacitance detection.

It should be understood that the first channel and the second channel may be any two channels in the screen. The first channel and the second channel may be two adjacent channels, such as TX shown in FIG. 1₁And TX₂Or RX_N-1And RX_N(ii) a The first channel and the second channel may also be two channels that are not adjacent.

The capacitance detection circuit 200 of this embodiment can realize full channel detection (All Driving). When the screen includes a plurality of lateral channels and a plurality of longitudinal channels, the capacitance of the first channel of the plurality of lateral channels and the capacitance of the first channel of the plurality of longitudinal channels may be detected in parallel in each detection period.

For example, for TX in FIG. 1₁To TX_MAnd RX₁To RX_NDetection is performed assuming that M and N are even numbers. TX can be used in the first round of self-capacitance detection₁、TX₃、TX₅、……、TX_M-1As a first channel, TX₂、TX₄、TX₆、……、TX_MRespectively as and TX₁、TX₃、TX₅、……、TX_M-1Corresponding second channel to detect TX₁、TX₃、TX₅、……、TX_M-1The amount of capacitance change of (c). Wherein, in detecting TX₁、TX₃、TX₅、……、TX_M-1While RX is connected₁、RX₃、RX₅、……、RX_N-1As a first channel, will RX₂、RX₄、RX₆、……、TX_NRespectively as and RX₁、RX₃、RX₅、……、RX_N-1Corresponding second channel, thereby detecting RX₁、RX₃、RX₅、……、RX_N-1The amount of capacitance change of (c). TX can be adjusted during second round of self-capacitance detection₂、TX₄、TX₆、……、TX_MAs a first channel, TX₁、TX₃、TX₅、……、TX_M-1Respectively as and TX₂、TX₄、TX₆、……、TX_MCorresponding second channel to detect TX₂、TX₄、TX₆、……、TX_MThe amount of capacitance change of (c). Wherein, in detecting TX₂、TX₄、TX₆、……、TX_MWhile RX is connected₂、RX₄、RX₆、……、RX_NAs a first channel, will RX₁、RX₃、RX₅、……、RX_N-1Respectively as and RX₂、RX₄、RX₆、……、RX_NCorresponding second channel, thereby detecting RX₂、RX₄、RX₆、……、RX_NThe amount of capacitance change of (c). Thus, through the two detection rounds, the capacitance variation of all the channels in the screen can be detected.

When M or N is an even number, when detecting an even number of transverse channels or longitudinal channels, self-contained detection can be performed in the above manner, that is: taking the odd-numbered channel as the first channel and the even-numbered channel as the second channel, and taking the even-numbered channel as the first channel and the odd-numbered channel as the second channel; or, the even numbered channel is taken as the first channel and the odd numbered channel is taken as the second channel, and then the odd numbered channel is taken as the first channel and the even numbered channel is taken as the second channel.

When M or N is an odd number, when detecting odd number of transverse channels or longitudinal channels, the remaining even number of channels except the first channel may be detected first, and then the remaining even number of channels except the last channel may be detected. Wherein the remaining even number of channels can be detected in the manner described above. For example, with TX in FIG. 1₁To TX_MFor example, M is odd, then TX can be paired first₁To TX_M-1Detect and then to TX₂To TX_MPerforming detection, at this time, TX₁And TX_MIs detected at a frequency of TX₂To TX_M-11/2 for the detection frequency.

The above detection method is merely an example, and other detection methods may be adopted to perform self-contained detection on a plurality of channels. E.g. still with TX in FIG. 1₁To TX_MFor example, M is odd, then TX can be detected first₂To TX_MI.e. not detecting TX₁(ii) a Then detects TX₁、TX₂、TX₄To TX_MI.e. not detecting TX₃(ii) a Then detects TX₁To TX₄And TX₆To TX_MI.e. not detecting TX₅(ii) a … …, respectively; final detection of TX₁To TX_M-1I.e. not detecting TX_M. Thus, TX₁、TX₃、……、TX_M-2、TX_MThe detection frequency of each channel in the channel is (K-1)/K, K is TX₁、TX₃、……、TX_M-2、TX_MThe number of the cells. Therefore, when the number of the channels is large, the detection frequency difference of each channel is not large, and the capacitance detection result cannot be greatly influenced.

Optionally, in one implementation, as shown in fig. 3, the capacitance detection circuit 200 further includes a compensation circuit 250. The compensation circuit 250 includes a cancellation capacitor C_CEqual compensation capacitance Cp, C_CIs connected with the second channel. The release circuit 230 is further connected to the compensation capacitor 250, and is used for charging and discharging the compensation capacitor Cp.

It should be understood that the compensation capacitor Cp and the cancellation capacitor C_CEqual, i.e. Cp = C_CThe first channel and the second channel in the capacitance detection process can be symmetrical, namely the channel to be detected and the noise reference channel are symmetrical, so that the channel to be detected and the noise reference channel have equal influence on the capacitance detection process, and noise cancellation is facilitated.

The detection principle of the capacitance detection circuit 200 is described below with reference to fig. 3 and 4.

Optionally, in one implementation, one detection cycle of the capacitance detection circuit 200 includes a first phase, a second phase, and a third phase, where:

in the first stage, the driving circuit 210 charges or discharges the first channel and the second channel, and the cancellation circuit 220 charges or discharges the cancellation capacitor C_CThe discharge circuit 230 charges or discharges the compensation capacitor Cp to a predetermined voltage;

in the second stage, the first channel and the cancellation capacitor C_CTo transfer charge therebetween to offset the capacitance C_CCounteracting the base capacitance C of the first channel_X1The release circuit 230 charges or discharges the second channel to a preset voltage;

in the third stage, the first channel and the second channel input the capacitance signal to the amplifying circuit 240, and the amplifying circuit 240 outputs a voltage signal according to the capacitance signal of the first channel and the capacitance signal of the second channel.

For example, in one implementation, as shown in fig. 3 and 4, in a first phase T1, switches K1, K2, and K6 are closed, and the remaining switches are open. The driving circuit 210 charges the first channel and the second channel, for example, to a power supply voltage. Wherein the capacitance of the first channel comprises a base capacitance C_X1And with respect to the base capacitance C_X1Capacitance variation △ C_X1The capacitance of the second channel includes a base capacitance C_X2And with respect to the base capacitance C_X2Capacitance variation △ C_X2。

In a second phase T2, switches K8, K6 and K5 are closed, the remaining switches are open. When the switch K8 is closed, the cancellation circuit220 are coupled to a first channel, and charge on the first channel is directed to a cancellation capacitor C in cancellation circuit 220_CIs transferred thereby by canceling the capacitance C_CCounteracting the base capacitance C of the first channel_X1. In the ideal case, the capacitance of the first channel remains only with respect to the base capacitance C after cancellation_X1Capacitance variation △ C_X1. When the switches K6 and K5 are closed, the release circuit 230 is connected to the second channel and the compensation circuit 250, the release circuit 230 pulls the second channel directly to a predetermined voltage, and charges the compensation capacitor Cp in the compensation circuit 250 to a predetermined voltage, such as V_CMIThereby discharging all charge on the second channel and compensation capacitor Cp.

In a third phase T3, switches K3 and K4 are closed and the remaining switches are open. Thus, the first channel and the second channel input capacitance signals to the amplifying circuit 240, that is, charges remaining on the first channel and the second channel are transferred to the amplifying circuit 240.

The capacitance signal input to the amplifying circuit 240 by the first channel is a capacitance variation △ C of the first channel_X1Corresponding capacitance signal, and due to the influence of screen noise, a noise signal still exists on the first channel, and the charge on the second channel is released, so that only the noise signal is left. By differentiating the capacitance signals of the first channel and the second channel through the amplifying circuit 240, the noise signal in the first channel can be eliminated, and the voltage signal V is output_OUTThe voltage signal V_OUTThe capacitance variation △ C of the first channel after the noise signal is cancelled can be reflected_X1According to the voltage signal V output by the amplifying circuit 240_OUTThe capacitance variation △ C of the first channel can be known_X1。

For another example, in another implementation, in the first phase T1, switches K1 and K2 are closed and the remaining switches are open. The first and second channels discharge to the driving circuit 210, for example to 0. Wherein the capacitance of the first channel comprises a base capacitance C_X1And with respect to the base capacitance C_X1Capacitance variation △ C_X1The capacitance of the second channel includes a base capacitance C_X2And with respect to the base capacitance C_X2Capacitance variation △ C_X2。

In a second phase T2, switches K8, K6 and K5 are closed, the remaining switches are open. When the switch K8 is closed, the cancellation circuit 220 is connected to the first channel, and the cancellation capacitor C in the cancellation circuit 220_CCharge transfer to the first channel, thereby canceling the capacitance C_CCounteracting the base capacitance C of the first channel_X1. In the ideal case, the capacitance of the first channel remains only with respect to the base capacitance C after cancellation_X1Capacitance variation △ C_X1. When the switches K6 and K5 are closed, the release circuit 230 is connected to the second channel and the compensation circuit 250, the release circuit 230 pulls the second channel directly to a predetermined voltage, and charges the compensation capacitor Cp in the compensation circuit 250 to a predetermined voltage, such as V_CMIThereby discharging all charge on the second channel and compensation capacitor Cp.

In a third phase T3, switches K3 and K4 are closed and the remaining switches are open. So that the first and second channels input the capacitance signal to the amplifying circuit 240.

The capacitance signal input to the amplifying circuit 240 by the first channel is a capacitance variation △ C of the first channel_X1Corresponding capacitance signal, and due to the influence of screen noise, a noise signal still exists on the first channel, and the charge on the second channel is released, so that only the noise signal is left. By differentiating the capacitance signals of the first channel and the second channel through the amplifying circuit 240, the noise signal in the first channel can be eliminated, and the voltage signal V is output_OUTThe voltage signal V_OUTThe capacitance variation △ C of the first channel after the noise signal is cancelled can be reflected_X1According to the voltage signal V output by the amplifying circuit 240_OUTThe capacitance variation △ C of the first channel can be known_X1。

It can be seen that the basic capacitance C for the first channel can be realized by the cancellation circuit 220_X1The cancellation of (C) may be achieved by the release circuit 230 for the base capacitance C of the second channel_X2And a capacitance variation △ C_X2So that the amplifying circuit 240 inputs to the first channel and the second channelAfter the capacitance signal is differentiated, the capacitance of the first channel after the noise signal is cancelled relative to the basic capacitance C can be obtained_X1Capacitance variation △ C_X1The sensitivity and accuracy of capacitance detection are improved.

It should be understood that the embodiment of the present application does not limit the preset voltage, and preferably, the preset voltage is a common-mode voltage of the input terminals of the amplifying circuit, or the preset voltage is a neutral point voltage, which is denoted as V_CMI。V_CMIE.g. equal to the supply voltage V_CCOne half of (i.e. V)_CMI=V_CC/2。

The embodiment of the present application does not limit the specific circuit structure of the capacitance detection circuit 200. Two possible implementations of the circuit structure, namely, the mode 1 and the mode 2, are provided below in conjunction with fig. 5 to 8 to implement the self-capacitance detection of the first channel.

Optionally, in an implementation, the driving circuit 210 includes a first switch K1 and a second switch K2, and one end of the first channel is connected to the power voltage V through the first switch K1_CCAnd is connected to one input terminal of the amplifying circuit 240 through the third switch K3, and the other end of the first channel is connected to ground. One end of the second channel is connected to the power voltage through the second switch K2, and is connected to the other input terminal of the amplifying circuit 240 through the fourth switch K4, and the other end of the second channel is connected to ground.

Optionally, in one implementation, the release circuit 230 includes a fifth switch K5 and a sixth switch K6, one end of the compensation capacitor Cp is connected to the preset voltage through the fifth switch K5, and is connected to the second channel through the sixth switch K6, and the other end of the compensation capacitor Cp is grounded.

In mode 1, the capacitance C is cancelled_CEqual to the base capacitance C of the first channel_X1。

At this time, optionally, in one implementation, the cancellation circuit 220 includes a seventh switch K7 and an eighth switch K8, one end of the cancellation capacitor 220 is connected to the ground through the seventh switch K7, and is connected to the first channel through the eighth switch K8, and the cancellation capacitor C is connected to the first channel_CAnd the other end of the same is grounded.

Referring to fig. 5 and 6, in the first phase T1 of the sensing period, the first switch K1, the second switch K2, the seventh switch K7 and the fifth switch K5 are closed, wherein the first channel and the second channel are charged to the power voltage V_CCCancellation capacitance C_CDischarged to 0, the compensation capacitor Cp is charged to a predetermined voltage, e.g. V_CMI(ii) a In a second phase T2, the eighth switch K8, the fifth switch K5 and the sixth switch K6 are closed, wherein the first channel is towards the cancellation capacitance C_CDischarging, the second channel to a predetermined voltage, e.g. V_CMI(ii) a In the third stage T3, the eighth switch K8, the sixth switch K6, the third switch K3 and the fourth switch K4 are closed, wherein the first channel and the second channel discharge to the amplifying circuit 240.

It can be seen that in the second stage T2, the capacitance C is cancelled_CThe basic capacitance C of the first channel needs to be cancelled_X1Then the capacitance C is cancelled_CShould be in contact with the base capacitance C of the first channel_X1Equal, i.e. C_C=C_X1After cancellation, the capacitance signal of the first channel includes a capacitance change △ C_X1And screen noise induced capacitance changes. Since the second channel is connected to the voltage V_CMIThe charges on the second channel are all released, so only the noise signal from the screen remains on the second channel. In the third stage T3, after the amplifying circuit 240 differentiates the capacitance signals input by the first channel and the second channel, the capacitance of the first channel with respect to the base capacitance C after the noise signal is cancelled can be obtained_X1Capacitance variation △ C_X1Therefore, the sensitivity and the accuracy of capacitance detection are improved.

The capacitance detection circuit of the embodiment of the application can be applied to various scenes, for example, when the capacitance detection circuit is applied to the touch field, the touch of a finger on a screen can cause a corresponding channel to generate capacitance variation relative to a basic capacitor, and the capacitance variation of the channel can be obtained by adopting the circuit, so that the touch information of the finger can be obtained.

When no finger touches the corresponding position of the first channel, the cancellation capacitance C due to the second stage T2_CA base capacitor C_X1A compensation capacitor Cp,And C_X2And △ C_X2The corresponding voltages are all V_CMINo charge is transferred to the amplifier circuit 240, and the voltage signal V output from the amplifier circuit 240_OUTA constant value such as 0; when a finger touches the touch screen, the offset capacitor C is connected in parallel_CA base capacitor C_X1And a capacitance variation △ C_X1Corresponding voltage after charge transfer is greater than V_CMIVoltage signal V output from the amplifying circuit 240_OUTThere are variations.

The offset capacitance C_CCan be an adjustable capacitor, when no finger touches the corresponding position of the first channel, the C is adjusted_CSuch that the voltage signal V output by the amplifying circuit 240_OUTIs a constant value, e.g., 0, at which time C is deemed to have been adjusted_C=C_X1. When capacitance detection is performed later, if a finger touches the touch panel, the offset capacitance C is obtained_CCan cancel the basic capacitance C_X1. Within an acceptable error range, C can also be adjusted_C≈C_X1So as to cancel the capacitance C_CCounteracting sufficient base capacitance C_X1And (4) finishing.

In order to suppress the influence of the low-frequency interference signal on the capacitance detection circuit, further, the self-capacitance of the first channel can be detected in a correlated double sampling manner.

Optionally, in an implementation manner, the driving circuit 210 further includes a ninth switch K9 and a tenth switch K10, one end of the first channel is connected to the ground through the ninth switch K9, one end of the second channel is connected to the ground through the tenth switch K10, the cancellation circuit 220 further includes an eleventh switch K11, and the cancellation capacitor C is connected to the ground through the eleventh switch K11_CIs connected to the supply voltage V via an eleventh switch K11_CC。

At this time, optionally, in one implementation, the detection period further includes a fourth stage T4, a fifth stage T5, and a sixth stage T6. Wherein, for example, as shown in fig. 5 and 6, in the fourth stage T4, the ninth switch K9, the tenth switch K10, the eleventh switch K11 and the fifth switch K5 are closed, wherein the first channel and the second channel are discharged to 0, and the cancellation capacitor C is offset_CCharging to the power supply voltage V_CCThe compensation capacitor Cp is charged toProvided with a voltage, e.g. V_CMI(ii) a In a fifth phase T5, the eighth switch K8, the fifth switch K5 and the sixth switch K6 are closed, wherein the counteracting capacitance C_CDischarging to the first channel, and pulling the voltage of the second channel to a predetermined voltage, e.g. V_CMI(ii) a In the sixth phase T6, the eighth switch K8, the sixth switch K6, the third switch K3, and the fourth switch K4 are closed, wherein the amplifying circuit 240 discharges to the first channel and the second channel.

At this time, the self-capacitance of the first channel is relative to the base capacitance C_X1Capacitance variation △ C_X1It is determined according to the voltage signals outputted from the amplifying circuit 240 in the third stage T3 and the sixth stage T6 as shown in fig. 6, the voltage signals outputted from the amplifying circuit 240 are equal but opposite in the third stage T3 and the sixth stage T6, and thus, the capacitance variation △ C of the first channel after canceling the screen noise can be determined by the voltage signals outputted from the third stage T3 and the sixth stage T6_X1. For example, assume that the voltage signal output by the amplifying circuit 240 in the third stage T3 is V_OUT+V’The voltage signal output at the sixth stage T6 is-V_OUT+V’In which V is’For low-frequency interference voltage, then according to [ (V)_OUT+V’）-（-V_OUT+V’）]The low-frequency interference noise V can be counteracted by 2’And obtaining a voltage signal V_OUTThereby determining the capacitance variation △ C of the first channel_X1。

Mode 2

In the mode 2, the capacitance C is cancelled_CA base capacitance C smaller than the first channel_X1Therefore, the area of the offset capacitor is reduced, and the cost of the capacitance detection circuit is also reduced.

At this time, optionally, in one implementation, the cancellation circuit 220 includes a seventh switch K7, an eighth switch K8, a twelfth switch K12 and a thirteenth switch K13, and a cancellation capacitor C_CIs connected to ground through a seventh switch K7 and to the supply voltage V through an eighth switch K8_CCCancellation capacitance C_CIs connected to the supply voltage V via a twelfth switch K12 and a thirteenth switch K13, respectively_CCAnd a ground.

Referring to fig. 7 and 8, in the first phase T1 of the sensing period, the first switch K1, the second switch K2, the seventh switch K7, the fifth switch K5 and the twelfth switch K12 are closed, wherein the first channel and the second channel are charged to the power voltage V_CCCancellation capacitance C_CThe voltage of the upper plate is 0 and the voltage of the lower plate is the power voltage V_CCThe compensation capacitor being charged to a predetermined voltage, e.g. V_CMI(ii) a In the second stage T2, the eighth switch K8, the fifth switch K5, the sixth switch K6 and the thirteenth switch 13 are closed, wherein the second channel is discharged to a preset voltage, for example, V_CMICancellation capacitance C_CThe voltage of the upper polar plate is negative power voltage-V_CCAnd the voltage of the lower plate is 0, so that the first channel counteracts the capacitance C_CDischarging; in the third stage T3, the eighth switch K8, the sixth switch K6, the third switch K3, the fourth switch K4 and the thirteenth switch K13 are closed, wherein the first channel and the second channel discharge to the amplifying circuit 240.

It can be seen that in the second stage T2, the capacitance C is cancelled_CThe basic capacitance C of the first channel needs to be cancelled_X1With a predetermined voltage V_CCFor example,/2, then the capacitance C is cancelled_CShould be equal to the base capacitance C of the first channel_X11/3, i.e. C_C=C_X1/3. In particular, in the second stage T2, the capacitance C is cancelled_CThe voltage of the upper polar plate and the lower polar plate is respectively-V_CCAnd 0, then the cancellation capacitance C_CAnd the first channel, when the capacitance C is offset_CTo the base capacitance C of the first channel_X1After the cancellation, the capacitance C is cancelled_CAnd a base capacitor C_X1All become V_CMII.e. V_CC/2. Thus, the capacitance C is cancelled_Cfrom-V to_CCChange to V_CC2, by 1.5V_CC(ii) a And the basic capacitance C_X1Corresponding voltage from V_CCChange to V_CC2, by 0.5V_CC. From the formula Q = U C, 0.5C_X1=1.5*C_CThus C_C=C_X1/3. After cancellation, the capacitance signal of the first channel includes a capacitance variationChemical quantity △ C_X1And screen noise induced capacitance changes. Since the second channel is connected to the voltage V_CMIThe charges on the second channel are all released, so only the noise signal from the screen remains on the second channel. In the third stage T3, after the amplifying circuit 240 differentiates the capacitance signals input by the first channel and the second channel, the capacitance of the first channel with respect to the base capacitance C after the noise signal is cancelled can be obtained_X1Capacitance variation △ C_X1Therefore, the sensitivity and the accuracy of capacitance detection are improved.

When the capacitance detection circuit is applied to the field of touch control, the touch of a finger on a screen can cause a corresponding channel to generate capacitance variation relative to a basic capacitor, and the capacitance variation of the channel can be obtained by adopting the circuit, so that the touch information of the finger can be obtained.

When no finger touches the corresponding position of the first channel, the cancellation capacitance C due to the second stage T2_CA base capacitor C_X1Compensation capacitors Cp and C_X2And △ C_X2The corresponding voltages are all V_CMINo charge is transferred to the amplifier circuit 240, and the voltage signal V output from the amplifier circuit 240_OUTA constant value such as 0; when a finger touches the touch screen, the offset capacitor C is connected in parallel_CA base capacitor C_X1And a capacitance variation △ C_X1Corresponding voltage after charge transfer is greater than V_CMIVoltage signal V output from the amplifying circuit 240_OUTThere are variations.

The offset capacitance C_CCan be an adjustable capacitor, when no finger touches the corresponding position of the first channel, the C is adjusted_CSuch that the voltage signal V output by the amplifying circuit 240_OUTIs a constant value, e.g., 0, at which time C is deemed to have been adjusted_C=C_X1/3. When capacitance detection is performed later, if a finger touches the touch panel, the offset capacitance C is obtained_CCan cancel the basic capacitance C_X1. Within an acceptable error range, C can also be adjusted_C≈C_X1/3, making the offset capacitance C_CCounteracting sufficient base capacitance C_X1And (4) finishing.

In order to suppress the influence of the low-frequency interference signal on the capacitance detection circuit, further, the self-capacitance of the first channel can be detected in a correlated double sampling manner.

Optionally, in an implementation manner, the driving circuit 210 further includes a ninth switch K9 and a tenth switch K10, one end of the first channel is connected to the ground through the ninth switch K9, one end of the second channel is connected to the ground through the tenth switch K10, the cancellation circuit 220 further includes an eleventh switch K11, and the cancellation capacitor C is connected to the ground through the eleventh switch K11_CIs connected to the supply voltage V via an eleventh switch K11_CC。

At this time, optionally, in one implementation, the detection period further includes a fourth stage T4, a fifth stage T5, and a sixth stage T6. For example, as shown in fig. 7 and 8, in the fourth stage T4, the ninth switch K9, the tenth switch K10, the eleventh switch K11, the fifth switch K5 and the thirteenth switch K13 are closed, wherein the first channel and the second channel are discharged to 0, and the cancellation capacitor C is offset_CCharging to the power supply voltage V_CCThe compensation capacitor Cp is charged to a predetermined voltage, e.g. V_CMI(ii) a In a fifth phase T5, the eighth switch K8, the fifth switch K5, the sixth switch K6 and the twelfth switch K12 are closed, wherein the cancellation capacitor C is closed_CDischarging to the first channel, and pulling the voltage of the second channel to a predetermined voltage, e.g. V_CMI(ii) a In a sixth phase T6, the eighth switch K8, the sixth switch K6, the third switch K3, the fourth switch K4, and the twelfth switch K12 are closed, wherein the amplification circuit 240 discharges to the first channel and the second channel.

At this time, the self-capacitance of the first channel is relative to the base capacitance C_X1Capacitance variation △ C_X1It is determined according to the voltage signals outputted from the amplifying circuit 240 in the third stage T3 and the sixth stage T6 as shown in fig. 8, the voltage signals outputted from the amplifying circuit 240 are equal but opposite in the third stage T3 and the sixth stage T6, and thus, the capacitance variation △ C of the first channel after canceling the screen noise can be determined by the voltage signals outputted from the third stage T3 and the sixth stage T6_X1. For example, assume that the voltage signal output by the amplifying circuit 240 in the third stage T3 is V_OUT+V’In the sixth placeThe voltage signal output from the stage T6 is-V_OUT+V’In which V is’For low-frequency interference voltage, then according to [ (V)_OUT+V’）-（-V_OUT+V’）]The low-frequency interference noise V can be counteracted by 2’And obtaining a voltage signal V_OUTThereby determining the capacitance variation △ C of the first channel_X1。

It should be understood that, in the modes 1 and 2, in one detection of the first channel, the fourth stage T4 to the sixth stage T6 may be performed first, and then the first stage T1 to the third stage T3 may be performed; alternatively, only the first to third stages T1 to T3 are performed; alternatively, only the fourth to sixth stages T4 to T6 are performed. This is not limited in this application.

In the embodiment of the present application, the amplifying circuit 240 is, for example, a Programmable Gain Amplifier (PGA) circuit, which includes a differential operational amplifier, so as to collect a capacitance signal by using the differential operational amplifier to implement capacitance detection. The input end and the output end of the differential operational amplifier can be connected across a feedback resistor, for example, so that signals can be collected through the feedback resistor.

In addition, the capacitance detection circuit 200 may further include a filter circuit, and the filter circuit is connected to the amplifying circuit 520 and configured to filter the voltage signal output by the amplifying circuit 520. Such as the Anti-aliasing Filter (AAF) 260 shown in fig. 3.

Further, the capacitance detection circuit 500 may further include an analog-to-digital conversion circuit, which is connected to the filter circuit and is configured to convert the filtered voltage signal into a digital signal. Such as Analog to Digital Converter (ADC) 270 shown in fig. 3.

The embodiment of the present application further provides a touch chip, which includes the capacitance detection circuit 200 in the various embodiments of the present application.

An embodiment of the present application further provides an electronic device, including: a screen; and, the touch chip in the various embodiments of the present application described above.

By way of example and not limitation, the electronic device in the embodiments of the present application may be a portable or mobile computing device such as a terminal device, a mobile phone, a tablet computer, a notebook computer, a desktop computer, a game device, an in-vehicle electronic device, or a wearable smart device, and other electronic devices such as an electronic database, an automobile, and an Automated Teller Machine (ATM). The wearable intelligent device comprises a device which has complete functions and large size and can realize complete or partial functions without depending on a smart phone, such as a smart watch or smart glasses and the like; and, only focus on a certain kind of application function, and need with other equipment such as the equipment that the smart mobile phone cooperation was used, for example, all kinds of intelligent bracelet, intelligent ornament etc. that carry out the physical sign monitoring.

It should be noted that, without conflict, the embodiments and/or technical features in the embodiments described in the present application may be arbitrarily combined with each other, and the technical solutions obtained after the combination also fall within the protection scope of the present application.

It should be understood that the specific examples in the embodiments of the present application are for the purpose of promoting a better understanding of the embodiments of the present application, and are not intended to limit the scope of the embodiments of the present application, and that various modifications and variations can be made by those skilled in the art based on the above embodiments and fall within the scope of the present application.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.