阅读说明：本技术 一种斩波稳零比较电路 (Chopper-stabilized comparison circuit ) 是由 廖望 侯江 郭亮 陈雪 苏豪 谢向阳 刘凡 于 2020-07-16 设计创作，主要内容包括：本发明提出一种斩波稳零比较电路,包括：工作状态选择模块,用于选择启动采样或比较过程；多级比较/放大模块,用于将经过采样的输入信号与基准信号进行比较,并对比较结果进行放大；过载保护模块,设置于相邻两级比较/放大模块之间,用于防止前一级所述比较/放大模块的输出过载；本发明结构简单、功耗较低,速度快。(The invention provides a chopper-stabilized comparison circuit, which comprises: the working state selection module is used for selecting and starting a sampling or comparison process; the multi-stage comparison/amplification module is used for comparing the sampled input signal with a reference signal and amplifying a comparison result; the overload protection module is arranged between two adjacent stages of comparison/amplification modules and is used for preventing the output of the comparison/amplification module at the previous stage from being overloaded; the invention has simple structure, low power consumption and high speed.)

1. A chopper-stabilized comparator circuit, comprising:

the working state selection module is used for selecting and starting a sampling or comparison process;

the multi-stage comparison/amplification module is used for comparing the sampled input signal with a reference signal and amplifying a comparison result;

and the overload protection module is arranged between two adjacent stages of comparison/amplification modules and is used for preventing the output of the comparison/amplification module at the previous stage from being overloaded.

2. The chopper-stabilized comparison circuit of claim 1, wherein the operating state selection module comprises a first switch and a second switch, one end of the first switch and one end of the second switch are connected to serve as output ends; the other end of the first switch is connected with the input signal; the other end of the second switch is connected with the reference signal.

3. The chopper-stabilized comparator circuit of claim 2, wherein a sampling process is initiated when the first switch is closed and the second switch is open; when the first switch is open and the second switch is closed, a comparison process is initiated.

4. The chopper-stabilized comparison circuit of claim 1, wherein each stage of the comparing/amplifying module comprises a sampling/comparing unit for sampling or comparing the input signals, an inverse amplifying unit for amplifying the compared signals, and a suppressing unit for suppressing channel charge injection effects; the input end of the sampling/comparing unit is connected with the output end of the working state selecting module or the output end of the previous stage of the comparing/amplifying module; the output end of the sampling/comparing unit is connected with one end of the reverse amplifying unit and is also connected with the output end of the inhibiting unit; and the output end of the reverse amplification unit is connected with the input end of the overload protection module.

5. The chopper-stabilized comparison circuit of claim 4, wherein the inverting amplification unit comprises an inverting amplifier and a third switch, the third switch being connected in parallel with the inverting amplifier; when the sampling process is started, the third switch is closed; when the comparison process is started, the third switch is turned off.

6. The chopper-stabilized comparator circuit of claim 5, wherein the inverting amplifier comprises a first MOS transistor and a second MOS transistor, gates of the first MOS transistor and the second MOS transistor are connected to serve as an input terminal of the inverting amplifier, drains of the first MOS transistor and the second MOS transistor are connected to serve as an output terminal of the inverting amplifier, a source of the first MOS transistor is connected to a high level, and a source of the second MOS transistor is grounded.

7. The chopper-stabilized comparison circuit of claim 6, wherein the first MOS transistor is a PMOS transistor, and the second MOS transistor is an NMOS transistor.

8. The chopper-stabilized comparison circuit according to claim 1, wherein the overload protection module includes a third MOS transistor and a fourth MOS transistor, a drain of the third MOS transistor is connected to a high level, and a gate of the third MOS transistor is connected to the output terminal of the inverting amplification unit; the source electrode of the third MOS tube is connected with the drain electrode of the fourth MOS tube to serve as the output end of the overload protection circuit; the grid electrode of the fourth MOS tube is connected with bias voltage; the source electrode of the fourth MOS tube is grounded; and the third MOS tube and the fourth MOS tube both adopt NMOS tubes.

9. The chopper-stabilized comparator circuit of claim 1, wherein the sampling/comparing unit is a capacitor.

10. The chopper-stabilized comparison circuit of claim 1, wherein the suppression unit comprises at least one NMOS transistor, and a drain and a source of the NMOS transistor are connected as an output terminal; and the grid electrode of the NMOS tube is connected with the inverted signal of the output end.

Technical Field

The invention relates to the technical field of analog or analog-digital hybrid integrated circuits, in particular to a chopper-stabilized comparison circuit.

Background

Successive Approximation Register (SAR) type ADC is one of the commonly used ADC structure types, has simple structure, easy integration and low power consumption, and is widely applied to the field of measurement and control. The comparator is a key unit in the successive approximation type analog-to-digital converter, and the performance of the comparator influences the performance of the whole analog-to-digital converter. A comparator is typically used to compare two input signals and generate an output signal that represents the result of the comparison of the two input signals. In order to realize high-precision application, the conventional comparator circuit has a relatively complex structure, increases the power consumption of the circuit, influences the operation speed and further increases the circuit cost.

Disclosure of Invention

In view of the problems in the prior art, the invention provides a chopper-stabilized comparator circuit, which mainly solves the problems that the existing comparator circuit is relatively complex in structure and high in power consumption.

In order to achieve the above and other objects, the present invention adopts the following technical solutions.

A chopper-stabilized comparator circuit comprising:

the working state selection module is used for selecting and starting a sampling or comparison process;

the multi-stage comparison/amplification module is used for comparing the sampled input signal with a reference signal and amplifying a comparison result;

and the overload protection module is arranged between two adjacent stages of comparison/amplification modules and is used for preventing the output of the comparison/amplification module at the previous stage from being overloaded.

Optionally, the working state selection module includes a first switch and a second switch, and one end of the first switch and one end of the second switch are connected to serve as an output end; the other end of the first switch is connected with the input signal; the other end of the second switch is connected with the reference signal.

Optionally, when the first switch is closed and the second switch is open, starting a sampling process; when the first switch is open and the second switch is closed, a comparison process is initiated.

Optionally, each stage of the comparing/amplifying module includes a sampling/comparing unit for sampling or comparing the input signal, an inverse amplifying unit for amplifying the compared signal, and a suppressing unit for suppressing channel charge injection effect; the input end of the sampling/comparing unit is connected with the output end of the working state selecting module or the output end of the previous stage of the comparing/amplifying module; the output end of the sampling/comparing unit is connected with one end of the reverse amplifying unit and is also connected with the output end of the inhibiting unit; and the output end of the reverse amplification unit is connected with the input end of the overload protection module.

Optionally, the inverting amplification unit includes an inverting amplifier and a third switch, and the third switch is connected in parallel with the inverting amplifier; when the sampling process is started, the third switch is closed; when the comparison process is started, the third switch is turned off.

Optionally, the inverting amplifier includes a first MOS transistor and a second MOS transistor, gates of the first MOS transistor and the second MOS transistor are connected to serve as an input end of the inverting amplifier, drains of the first MOS transistor and the second MOS transistor are connected to serve as an output end of the inverting amplifier, a source of the first MOS transistor is connected to a high level, and a source of the second MOS transistor is grounded.

Optionally, the first MOS transistor is a PMOS transistor, and the second MOS transistor is an NMOS transistor.

Optionally, the overload protection module includes a third MOS transistor and a fourth MOS transistor, a drain of the third MOS transistor is connected to a high level, and a gate of the third MOS transistor is connected to the output end of the reverse amplification unit; the source electrode of the third MOS tube is connected with the drain electrode of the fourth MOS tube to serve as the output end of the overload protection circuit; the grid electrode of the fourth MOS tube is connected with bias voltage; the source electrode of the fourth MOS tube is grounded; and the third MOS tube and the fourth MOS tube both adopt NMOS tubes.

Optionally, the sampling/comparing unit is a capacitor.

Optionally, the suppression unit at least comprises an NMOS transistor, and a drain and a source of the NMOS transistor are connected as an output terminal; and the grid electrode of the NMOS tube is connected with the inverted signal of the output end.

As described above, the chopper-stabilized comparator circuit of the present invention has the following advantageous effects.

The multi-stage comparison/amplification module is used for carrying out amplification in the same direction for multiple times, so that the output signal of the circuit can be ensured to be identified by a post-stage circuit; the overload protection module can effectively prevent the output voltage from being too high, so that the circuit is overloaded, and the stability of the device is further ensured.

Drawings

Fig. 1 is a schematic diagram of a chopper-stabilized comparison circuit according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a reverse amplification unit according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of the operation of an inverting amplifier according to an embodiment of the invention.

FIG. 4 is a timing diagram illustrating an operation of the present invention.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.

It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.

Referring to fig. 1, the present invention provides a chopper-stabilized comparator circuit, including. The working state selection module is used for selecting and starting a sampling or comparison process;

the multi-stage comparison/amplification module is used for comparing the sampled input signal with a reference signal and amplifying a comparison result;

and the overload protection module is arranged between two adjacent stages of comparison/amplification modules and is used for preventing the output of the previous stage of comparison/amplification module from being overloaded.

In one embodiment, the working state selection module is composed of a first switch and a second switch, wherein one end of the first switch is not connected with one end of the second switch to serve as an output end, and the other end of the first switch is connected with an input signal; the other end of the second switch is connected with the reference signal. When the first switch is closed and the second switch is opened, starting a sampling process, and sampling an input signal through the multi-stage comparison/amplification module; when the first switch is turned off and the second switch is turned on, a comparison process is started, and a reference signal is input to the multi-stage comparison/amplification module, so that the sampled input signal is compared with the reference signal.

In one embodiment, each stage of comparison/amplification module comprises a sampling/comparison unit, a reverse amplification unit and a suppression unit, wherein the input end of the sampling/comparison unit is connected with the output end of the working state selection module or the output end of the previous stage of comparison/amplification module; the output end of the sampling/comparing unit is connected with one end of the reverse amplifying unit and is connected with the output end of the inhibiting unit; the output end of the reverse amplification unit is connected with the input end of the overload protection module. The sampling/comparing unit can adopt a sampling capacitor, the lower polar plate of the capacitor is connected with the output end of the working state selecting module or the output end of the previous stage comparing/amplifying module, and the upper polar plate is connected with the input end of the reverse amplifying unit and the output end of the inhibiting unit.

In one embodiment, the inverting amplification unit includes an inverting amplifier and a third switch, one end of the third switch is connected to the input terminal of the inverting amplifier, and the other end is connected to the output terminal of the inverting amplifier. When the sampling process is started, the third switch is closed, and the input end and the output end of the inverting amplifier are in short circuit; when the comparison process is initiated, the third switch is opened.

In one embodiment, the suppression unit at least comprises an NMOS tube, and the drain electrode and the source electrode of the NMOS tube are connected to be used as output ends; and the grid electrode of the NMOS tube is connected with the inverted signal of the output end. The suppression unit is mainly used for suppressing the sufficient charge injection effect brought by the closing of the third switch.

In an embodiment, the inverting amplifier includes a first MOS transistor and a second MOS transistor, gates of the first MOS transistor and the second MOS transistor are connected to serve as an input end of the inverting amplifier, a drain of the first MOS transistor and a drain of the second MOS transistor are connected to serve as an output end of the inverting amplifier, a source of the first MOS transistor is connected to a high level, and a source of the second MOS transistor is grounded. The first MOS transistor can adopt a PMOS transistor, and the second MOS transistor can adopt an NMOS transistor. When the third switch is closed, the first MOS tube and the second MOS tube are simultaneously conducted; when the third switch is switched off, the first MOS tube or the second MOS tube is controlled to be conducted according to the difference value of the reference signal and the input signal.

In one embodiment, the overload protection module comprises a third MOS transistor and a fourth MOS transistor, a drain of the third MOS transistor is connected to a high level, and a gate of the third MOS transistor is connected to an output end of the reverse amplification unit; the source electrode of the third MOS tube is connected with the drain electrode of the fourth MOS tube to be used as the output end of the overload protection circuit; the grid electrode of the fourth MOS tube is connected with bias voltage; the source electrode of the fourth MOS tube is grounded; and the third MOS tube and the fourth MOS tube both adopt NMOS tubes.

Specifically, referring to fig. 1, taking a chopper-stabilized comparison circuit of a three-stage comparison/amplification module as an example, the circuit includes 7 MOS transistors, 3 capacitors, 4 inverting amplifiers, and 5 switches.

The chopper stabilized comparator circuit 10 includes an NMOS transistor N1, an NMOS transistor N2, an NMOS transistor N3, an NMOS transistor N4, an NMOS transistor N5, an NMOS transistor N6, and an NMOS transistor N7. The grids of N1, N2 and N3 are connected with an S1' N signal, the source of N1 is connected with the drain, and the N1 is connected with the vin1 end and the upper polar plate of C1; the source electrode of the N2 is connected with the drain electrode and is connected with the upper electrode plates of vin2 and C2; the source electrode of N3 is connected with the drain electrode, the Vin3 end is connected with the upper polar plate of C3, the lower polar plate of C1 is connected with an input signal Vin through S1, the reference signal Vref is connected through S2, vout1 is connected with the grid electrode of N4, the drain electrode of N4 is connected with a power supply VDD, the source electrode is connected with the drain electrode of N5 and the lower polar plate of C2, the source electrode of N5 is grounded, and the grid electrode is connected with Vb; the vout2 is connected with an N6 grid, an N6 drain is connected with a power supply VDD, a source is connected with an N7 drain and a C3 bottom plate, an N7 source is grounded, and a grid is connected with Vb; vout3 is connected to the input of amp4 and the output of amp4 is connected to the OUT terminal.

The inverse amplifying unit 101 includes an NMOS transistor NM and a PMOS transistor PM. The NM gate is connected with the PM gate, is connected to the amplifier input Vin1 or Vin2 or Vin3 of each stage, has the source connected to the lowest potential, has the drain connected to the PM drain, is connected to the amplifier output Vout1 or Vout2 or Vout3 of each stage, has the source connected to the power supply VDD, and has the inverting amplifier input end and output end connected through the switch S1'.

The operation of the chopper-stabilized comparison circuit is divided into several processes of sampling, reference connection, amplification and comparison, the working timing sequence is shown in figure 4, the sampling is performed in the first step (at the moment t 1), S1 and S1 'are closed, S2 is opened, the inverted signal S1' N of the switch S1 'is opened, and S1' is connected into NMOS tubes N1, N2 and N3 which have the same size as that of S1 ', so that the channel charge injection effect caused by the closing of S1' is eliminated.

Fig. 2 is a structural diagram of the reverse amplifying unit 101, where an input end vin1/vin2/vin3 is shorted with an output end vout1/vout2/vout3, and at this time, the PMOS transistor PM and the NMOS transistor NM are turned on simultaneously, so that an output value ═ input value ═ vthx ═ VDD-VSS ═ Rn/(Rn + Rp) ], where Rp and Rn are the on-resistances of the PMOS transistor PM and the NMOS transistor NM, respectively, and vthx is the threshold of each stage of the reverse amplifier.

Taking amp1 as an example, during sampling, the C1 capacitor samples the charge Q (Vin-Vth1) × C1, and at the end of sampling (time t 2), S1 'and S1' N are turned off and on in advance.

Taking amp1 as an example, after sampling is finished, a reference signal (time t 3) is turned off at S1 and turned on at S2:

(Vref-Vin1)*C＝Q＝(Vin-Vth1)*C

in the comparison process, the voltage at Vin1 after charge redistribution is (Vref-Vin) + Vth1, that is, Vref is compared with Vin, as shown in fig. 3, when (Vref-Vin) is less than Vth1, vout1 tends to be in the PM conduction region; when (Vref-Vin) is larger than vth1, vout1 tends to NM conduction, and meanwhile, for the fact that the output of the first-stage amplifier may not reach the full amplitude to the ground, amp2 and amp3 are connected in series behind amp1 for amplification in the same method for multiple times, so that the output end OUT of the comparison circuit is ensured to reach a high-level H or low-level L state which can be identified by the logic of the SAR at the later stage.

Meanwhile, an overload prevention module 102 is added between the amplifiers, wherein N4 and N5, N6 and N7 form a source follower, and gates of N5 and N7 are connected with a fixed bias voltage Vb, so that the purpose of reducing the threshold voltage (vth) of an NMOS transistor by N4 and N6 in the comparison process of vout1 and vout2 is to prevent the overload of the comparison circuit caused by overhigh voltage of vout1 and vout 2.

In summary, the chopper-stabilized comparison circuit of the present invention realizes fast amplification of signals and outputs correct comparison signals; simple structure and low power consumption. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.