阅读说明：本技术 听筒控制电路和终端 (Earphone control circuit and terminal ) 是由 黄停 朱辰 冯英群 邱钰鹏 于 2020-04-30 设计创作，主要内容包括：本申请实施例提供一种听筒控制电路和终端,涉及电子设备技术领域,可以在具有立体声功能的终端上通过听筒发出超声波来实现接近传感器的功能。该听筒控制电路包括：智能功放模块、编译码器和听筒；智能功放模块通过第一开关模块电连接于听筒；第一开关模块包括第一开关器件单元,第一开关器件单元由MOSFET组成；第一开关模块还包括第一跟随单元,第一跟随单元用于使第一开关器件单元中MOSFET的栅极和漏极之间的电压差保持不变,且第一开关器件单元中MOSFET的栅极电压大于漏极电压；第二开关模块,编译码器通过第二开关模块电连接于听筒；第二开关模块包括第二开关器件单元,第二开关器件单元由MOSFET组成。本技术方案主要用于听筒的驱动。(The embodiment of the application provides a receiver control circuit and a terminal, relates to the technical field of electronic equipment, and can realize the function of a proximity sensor by sending ultrasonic waves through a receiver on the terminal with a stereo function. This earphone control circuit includes: the system comprises an intelligent power amplifier module, a codec and a receiver; the intelligent power amplifier module is electrically connected with the receiver through the first switch module; the first switching module comprises a first switching device unit, and the first switching device unit consists of a MOSFET; the first switch module further comprises a first following unit, wherein the first following unit is used for keeping the voltage difference between the grid electrode and the drain electrode of the MOSFET in the first switch device unit unchanged, and the grid electrode voltage of the MOSFET in the first switch device unit is greater than the drain electrode voltage; the second switch module is used for electrically connecting the codec with the receiver through the second switch module; the second switching module includes a second switching device unit composed of a MOSFET. The technical scheme is mainly used for driving the telephone receiver.)

1. An earpiece control circuit, comprising:

the system comprises an intelligent power amplifier module, a codec and a receiver;

the intelligent power amplifier module is electrically connected with the earphone through the first switch module;

the first switch module comprises a first switch device unit, the first switch device unit is connected between the intelligent power amplifier module and the receiver and used for controlling the connection and disconnection between the intelligent power amplifier module and the receiver, and the first switch device unit consists of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET);

the MOSFET in the first switch device unit is of an N type, the drain electrode of the MOSFET in the first switch device unit is electrically connected to the intelligent power amplifier module, and the source electrode of the MOSFET in the first switch device unit is electrically connected to the receiver;

the first switch module further comprises a first following unit, wherein the first following unit is used for keeping a voltage difference between a grid electrode and a drain electrode of the MOSFET in the first switch device unit unchanged, and the grid electrode voltage of the MOSFET in the first switch device unit is greater than the drain electrode voltage;

the second switch module is used for electrically connecting the codec with the receiver through the second switch module;

the second switch module comprises a second switch device unit, the second switch device unit is connected between the codec and the receiver and used for controlling the connection and the disconnection between the codec and the receiver, and the second switch device unit is composed of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET).

2. The handset control circuit of claim 1,

the MOSFET in the second switch device unit is of an N type, the source electrode of the MOSFET in the second switch device unit is electrically connected to the codec, and the drain electrode of the MOSFET in the second switch device unit is electrically connected to the receiver;

the second switching module further comprises a second follower unit for keeping a voltage difference between a gate and a source of the MOSFET in the second switching device unit constant.

3. The handset control circuit of claim 1,

the intelligent power amplifier module comprises a first output end and a second output end, and the receiver comprises a first input end and a second input end;

the first switching device unit comprises a first transistor and a second transistor, the first transistor and the second transistor are N-type MOSFETs, a source electrode of the first transistor is electrically connected to a first input end of the earphone, a drain electrode of the first transistor is electrically connected to a first output end of the intelligent power amplifier module, a source electrode of the second transistor is electrically connected to a second input end of the earphone, and a drain electrode of the second transistor is electrically connected to a second output end of the intelligent power amplifier module;

the first follower unit includes:

the first capacitor is connected between the grid electrode and the drain electrode of the first transistor in series;

a second capacitor connected in series between the gate and the drain of the second transistor;

a first resistor connected in series between the gate of the first transistor and a DC bias control node;

a second resistor connected in series between the gate of the second transistor and the DC bias control node.

4. The handset control circuit of claim 3, further comprising:

a third resistor connected in series between the DC bias control node and a DC bias voltage terminal;

a third transistor connected in series between the DC bias control node and a ground terminal.

5. The handset control circuit of claim 2,

the codec comprises a first output end and a second output end, and the earphone comprises a first input end and a second input end;

the second switching device unit comprises a fourth transistor and a fifth transistor, the fourth transistor and the fifth transistor are N-type MOSFETs, a source electrode of the fourth transistor is electrically connected to the first output end of the codec, a drain electrode of the fourth transistor is electrically connected to the first input end of the receiver, a source electrode of the fifth transistor is electrically connected to the second output end of the codec, and a drain electrode of the fifth transistor is electrically connected to the second input end of the receiver;

the second following unit includes:

a third capacitor connected in series between the source and the gate of the fourth transistor;

the fourth resistor is connected between the grid electrode of the fourth transistor and the first direct current bias control end in series;

a fourth capacitor connected in series between the source and the gate of the fifth transistor;

and the fifth resistor is connected between the grid electrode of the fifth transistor and the second direct current bias control end in series.

6. The handset control circuit of claim 5, further comprising:

the sixth resistor is connected in series between the source of the fourth transistor and the ground terminal, and the seventh resistor is connected in series between the source of the fifth transistor and the ground terminal.

7. The handset control circuit of claim 3, further comprising:

a fifth capacitor connected in series between the gate of the first transistor and the first input terminal of the handset;

a sixth capacitor connected in series between the gate of the second transistor and the second input of the handset.

8. A terminal, characterized in that it comprises an earpiece control circuit according to any one of claims 1 to 7.

Technical Field

The application relates to the technical field of electronic equipment, in particular to a receiver control circuit and a terminal.

Background

A proximity sensor is provided in a terminal such as a mobile phone, and the like, and is used for detecting the approach of an external object. Some functions of the terminal can be realized through the proximity sensor, for example, mistaken touch prevention in the process of mobile phone conversation, the screen is turned off when an external object is detected to be close to prevent mistaken touch, or the pocket mistaken touch prevention is realized through the same principle. Some cellular phones use an earpiece to emit ultrasonic waves and a microphone to receive the ultrasonic waves, thereby implementing the proximity sensor function. However, as the requirement of the user for the terminal sound quality is higher and higher, stereo is more and more applied to the mobile phone, stereo refers to that music is played through an earphone above and a loudspeaker below, and the required Power is higher at this time, so a Smart Power Amplifier (Smart PA) module with high efficiency is generally adopted for driving, however, due to the reasons that the Smart PA module is incompatible with the frequency of ultrasonic waves, the function of the proximity sensor cannot be realized by sending ultrasonic waves through the earphone on the terminal with the stereo function.

Disclosure of Invention

The technical scheme of the application provides a receiver control circuit and a terminal, and the function of a proximity sensor can be realized by sending ultrasonic waves through a receiver on the terminal with a stereo function.

In a first aspect, the present technical solution provides an earphone control circuit, including: the system comprises an intelligent power amplifier module, a codec and a receiver; the intelligent power amplifier module is electrically connected with the earphone through the first switch module; the first switch module comprises a first switch device unit, the first switch device unit is connected between the intelligent power amplifier module and the receiver and used for controlling the connection and the disconnection between the intelligent power amplifier module and the receiver, and the first switch device unit consists of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET); the MOSFET in the first switch device unit is of an N type, the drain electrode of the MOSFET in the first switch device unit is electrically connected to the intelligent power amplifier module, and the source electrode of the MOSFET in the first switch device unit is electrically connected to the receiver; the first switch module further comprises a first following unit, wherein the first following unit is used for keeping the voltage difference between the grid electrode and the drain electrode of the MOSFET in the first switch device unit unchanged, and the grid electrode voltage of the MOSFET in the first switch device unit is greater than the drain electrode voltage; the second switch module is used for electrically connecting the codec with the receiver through the second switch module; the second switch module comprises a second switch device unit, the second switch device unit is connected between the codec and the receiver and used for controlling the connection and the disconnection between the codec and the receiver, and the second switch device unit is composed of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET).

Optionally, the MOSFET in the second switching device unit is N-type, and the source of the MOSFET in the second switching device unit is electrically connected to the codec, and the drain of the MOSFET in the second switching device unit is electrically connected to the handset; the second switching module further includes a second follower unit for keeping a voltage difference between a gate and a source of the MOSFET in the second switching device unit constant.

Optionally, the smart power amplifier module includes a first output end and a second output end, and the receiver includes a first input end and a second input end; the first switching device unit comprises a first transistor and a second transistor, the first transistor and the second transistor are N-type MOSFETs, a source electrode of the first transistor is electrically connected to a first input end of the earphone, a drain electrode of the first transistor is electrically connected to a first output end of the intelligent power amplification module, a source electrode of the second transistor is electrically connected to a second input end of the earphone, and a drain electrode of the second transistor is electrically connected to a second output end of the intelligent power amplification module; the first following unit includes: the first capacitor is connected between the grid and the drain of the first transistor in series; the second capacitor is connected between the grid electrode and the drain electrode of the second transistor in series; the first resistor is connected between the grid of the first transistor and the direct current bias control node in series; and the second resistor is connected between the grid of the second transistor and the direct current bias control node in series.

Optionally, the earpiece control circuitry further comprises: the third resistor is connected between the direct current bias control node and the direct current bias voltage end in series; and the third transistor is connected in series between the direct current bias control node and the grounding end.

Optionally, the codec comprises a first output and a second output, and the handset comprises a first input and a second input; the second switching device unit comprises a fourth transistor and a fifth transistor, the fourth transistor and the fifth transistor are N-type MOSFETs, a source electrode of the fourth transistor is electrically connected to the first output end of the codec, a drain electrode of the fourth transistor is electrically connected to the first input end of the receiver, a source electrode of the fifth transistor is electrically connected to the second output end of the codec, and a drain electrode of the fifth transistor is electrically connected to the second input end of the receiver; the second following unit includes: the third capacitor is connected in series between the source electrode and the grid electrode of the fourth transistor; the fourth resistor is connected between the grid of the fourth transistor and the first direct current bias control end in series; the fourth capacitor is connected between the source electrode and the grid electrode of the fifth transistor in series; and the fifth resistor is connected between the grid electrode of the fifth transistor and the second direct current bias control end in series.

Optionally, the earpiece control circuitry further comprises: the sixth resistor is connected in series between the source of the fourth transistor and the ground terminal, and the seventh resistor is connected in series between the source of the fifth transistor and the ground terminal.

Optionally, the earpiece control circuitry further comprises: the fifth capacitor is connected in series between the grid electrode of the first transistor and the first input end of the receiver; and the sixth capacitor is connected between the grid electrode of the second transistor and the second input end of the receiver in series.

In a second aspect, the present application further provides a terminal, including the above earphone control circuit.

When stereo playing is needed, the receiver control circuit and the terminal control the codec and the receiver to be cut off through the second switch device unit composed of the MOSFET, the intelligent power amplifier module and the receiver to be switched on through the first switch device unit composed of the MOSFET, and normal transmission of PWM signals is guaranteed through the action of the first following unit, so that the receiver can be driven through the intelligent power amplifier module to realize stereo function, and at the moment, even if high voltage exists in the intelligent power amplifier module, adverse effects of the high voltage in the intelligent power amplifier module on the codec are reduced due to the cut-off action of the second switch device unit; when realizing the proximity sensor function through the earphone, at this moment, even if there is the negative pressure in the codec, because cut off between first switching device unit control intelligent power amplifier module and the earphone, reduced the adverse effect that negative pressure caused intelligent power amplifier module in the codec, switch on between second switching device unit control codec and the earphone, through codec drive earphone promptly, can make the earphone send the ultrasonic wave, in order to judge being close of external object, realize proximity sensor's function. That is to say, the earphone control circuit in the embodiment of the present application may implement the function of the proximity sensor by sending out ultrasonic waves through the earphone on the terminal with the stereo function.

Drawings

Fig. 1 is a schematic structural diagram of an earphone control circuit in an embodiment of the present application;

fig. 2 is a schematic structural diagram of another earphone control circuit in the embodiment of the present application;

fig. 3 is a schematic structural diagram of another earphone control circuit in the embodiment of the present application;

fig. 4 is a simulation diagram of the drain and gate voltages of the first transistor in fig. 3.

Detailed Description

The terminology used in the description of the embodiments section of the present application is for the purpose of describing particular embodiments of the present application only and is not intended to be limiting of the present application.

Before describing the embodiments of the present application, a description will be given of problems of the prior art and a process of the embodiments of the present application proposed by the inventor, where when the proximity sensor function is implemented by emitting ultrasonic waves from a receiver in the prior art, the receiver is driven by a Coder-Decoder (CODEC), and the stereo function cannot be implemented in this driving mode. If the stereo function is to be realized, a Smart PA module is required to be used for driving the receiver, however, the algorithm of the Smart PA module at present uses a signal with a sampling rate of 48k, the corresponding audio frequency range is 20-20 k, and the audio frequency range of the ultrasonic wave is 20 k-40 k, that is, the Smart PA module needs to use a sampling rate more than twice, for example, a sampling rate of 96k, which has high requirements on power consumption and memory; in addition, the ultrasonic algorithm is placed in a Smart PA module for realizing the stereo function, the computational space including the ultrasonic algorithm needs to be planned in advance on the premise of considering the stereo sound quality, and the improvement cost is high. For the above reasons, in order to enable the terminal to realize two functions of stereo sound and ultrasonic wave emission through a receiver, the inventor provides the idea that the switching between the Smart PA module and the CODEC is realized directly through the switch, however, since the voltage in the Smart PA module reaches 10V, the voltage in the CODEC is negative voltage, and there is no such switch with high withstand voltage and capable of conducting negative voltage at present; in the second idea, a capacitor or an amplifying circuit is connected in series between the CODEC and the receiver to raise the voltage transmitted from the CODEC to the receiver, so that the voltage is changed into positive voltage.

A technical solution of an embodiment of the present application is introduced as follows, and as shown in fig. 1, fig. 1 is a schematic structural diagram of an earpiece control circuit in an embodiment of the present application, and an embodiment of the present application provides an earpiece control circuit, including: the system comprises an intelligent power amplifier SmartPA module 1, a codec 2 and a receiver 3; the first switch module 41 is used for electrically connecting the intelligent power amplifier module 1 with the receiver 3 through the first switch module 41; the first switch module 41 comprises a first switch device unit 51, the first switch device unit 51 is connected between the intelligent power amplifier module 1 and the receiver 3, the first switch device unit 51 is used for controlling the connection and disconnection between the intelligent power amplifier module 1 and the receiver 3, and the first switch device unit 51 is composed of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET); the MOSFET in the first switching device unit 51 is of an N-type, a drain D of the MOSFET in the first switching device unit 51 is electrically connected to the smart power amplifier module 1, a source S of the MOSFET in the first switching device unit 51 is electrically connected to the receiver 3, and a gate G of the MOSFET in the first switching device unit 51 is used for controlling the on and off of the MOSFET; the first switching module 41 further includes a first following unit 61, the first following unit 61 is used for keeping the voltage difference between the gate G and the drain D of the MOSFET in the first switching device unit 51 constant, and the gate G voltage of the MOSFET in the first switching device unit 51 is greater than the drain D voltage; the second switch module 42, the codec 2 is electrically connected to the receiver 3 through the second switch module 42; the second switching module 42 includes a second switching device unit 52, the second switching device unit 52 is connected between the codec 2 and the handset 3, the second switching device unit 52 is configured to control on and off between the codec 2 and the handset 3, and the second switching device unit 52 is composed of a MOSFET.

Specifically, the first switching device unit 51 is composed of a MOSFET, and can conduct a high voltage in the smart power amplifier module 1; in addition, because the signal that intelligent power amplifier module 1 outputs is Pulse Width Modulation (PWM) signal, the high voltage in the Pulse is 10V for example, and the low pressure is 0V, in order to guarantee that both can be transmitted by MOSFET, therefore adopt N type MOSFET, in addition, when first switching device unit 51 control switches on between intelligent power amplifier module 1 and earphone 3, it is greater than drain electrode D voltage to control the grid G voltage of MOSFET in first switching device unit 51 through first following unit 61 to guarantee that MOSFET can all normally switch on in the transmission of 10V and 0V voltage. The working process of the receiver control circuit is that when stereo playing is needed, the second switch device unit 52 controls the codec 2 and the receiver 3 to be cut off, the first switch device unit 51 controls the intelligent power amplifier module 1 and the receiver 3 to be conducted, namely, the receiver 3 is driven by the intelligent power amplifier module 1, so that the stereo function is realized, and at the moment, even if negative pressure exists in the codec 2, the negative pressure cannot influence the receiver 3 due to the cut-off function of the second switch device unit 52; when realizing the proximity sensor function through earphone 3, cut off between intelligent power amplifier module 1 and earphone 3 through first switching device unit 51 control, at this moment, even if there is high pressure in the intelligent power amplifier module 1, also can not lead to the fact the influence to earphone 3, switch on between control codec 2 and earphone 3 through second switching device unit 52, drive earphone 3 through codec 2 promptly, can make earphone 3 send the ultrasonic wave, with the proximity of judging external object, realize proximity sensor's function.

When stereo playing is needed, the receiver control circuit controls the codec and the receiver to be cut off through the second switch device unit composed of the MOSFET, controls the intelligent power amplifier module and the receiver to be conducted through the first switch device unit composed of the MOSFET, and ensures normal transmission of PWM signals through the action of the first following unit, so that the receiver can be driven through the intelligent power amplifier module to realize stereo function, and at the moment, even if high voltage exists in the intelligent power amplifier module, the adverse effect of the high voltage in the intelligent power amplifier module on the codec is reduced due to the cut-off action of the second switch device unit; when realizing the proximity sensor function through the earphone, at this moment, even if there is the negative pressure in the codec, because cut off between first switching device unit control intelligent power amplifier module and the earphone, reduced the adverse effect that negative pressure caused intelligent power amplifier module in the codec, switch on between second switching device unit control codec and the earphone, through codec drive earphone promptly, can make the earphone send the ultrasonic wave, in order to judge being close of external object, realize proximity sensor's function. That is to say, the earphone control circuit in the embodiment of the present application may implement the function of the proximity sensor by sending out ultrasonic waves through the earphone on the terminal with the stereo function.

Alternatively, as shown in fig. 2, fig. 2 is a schematic structural diagram of another handset control circuit in the embodiment of the present application, a MOSFET in the second switching device unit 52 is N-type, a source S of the MOSFET in the second switching device unit 52 is electrically connected to the codec 2, and a drain D of the MOSFET in the second switching device unit 52 is electrically connected to the handset 3; the second switching module 42 further includes a second follower unit 62, and the second follower unit 62 is used for keeping the voltage difference between the gate G and the source S of the MOSFET in the second switching device unit 52 constant.

Specifically, the signal output by the codec 2 is an analog signal, and the influence of the fluctuation of the analog signal on the sound quality is large, so the second follower unit 62 is provided to keep the voltage difference between the gate G and the source S of the MOSFET in the second switching device unit 52 constant when the MOSFET is turned on, so as to ensure that the on-resistance of the MOSFET is constant, thereby reducing the fluctuation of the analog signal output by the codec 2.

Optionally, as shown IN fig. 3, fig. 3 is a schematic structural diagram of another earpiece control circuit IN this embodiment of the application, where the smart power amplifier module 1 includes a first output terminal P1 and a second output terminal N1, and the earpiece 3 includes a first input terminal IP and a second input terminal IN; the first switching device unit 51 includes a first transistor Q1 and a second transistor Q2, the first transistor Q1 and the second transistor Q2 are N-type MOSFETs, a source S1 of the first transistor Q1 is electrically connected to the first input IP of the handset 3, a drain D1 of the first transistor Q1 is electrically connected to the first output P1 of the smart power amplifier module 1, a source S1 of the second transistor Q2 is electrically connected to the second input IN of the handset 3, and a drain D2 of the second transistor Q2 is electrically connected to the second output N1 of the smart power amplifier module 1; the first following unit 61 includes: a first capacitor C1, the first capacitor C1 is connected in series between the gate G1 and the drain D1 of the first transistor Q1; a second capacitor C2, the second capacitor C2 is connected in series between the gate G2 and the drain D2 of the second transistor Q2; a first resistor R1, the first resistor R1 being connected in series between the gate G1 of the first transistor Q1 and the dc bias control node O; a second resistor R2 and a second resistor R2 are connected in series between the gate G2 of the second transistor Q2 and the dc bias control node O.

Specifically, the first output terminal P1 corresponds to the first input terminal IP, and the second output terminal N1 corresponds to the second input terminal IN, so that the control of the handset 3 is realized by differential signals. When the first switching device unit 51 controls the connection between the smart power amplifier module 1 and the handset 3, the dc bias control node O provides a dc bias voltage, and due to the action of the first follower unit 61, the voltage of the gate G1 of the first transistor Q1 is higher than the voltage of the drain D1 thereof, the voltage of the gate G2 of the second transistor Q2 is higher than the voltage of the drain D2 thereof, for example, the high voltage in the output waveform of the first output terminal P1 is 10V, and the low voltage is 0V, in order to ensure that the voltages of 0V to 10V can be transmitted to the handset 3, therefore, the voltage of the gate G1 of the first transistor Q1 is higher than the voltage of the drain D1 thereof by 5V, that is, it is ensured that the voltage difference between the gate G1 and the source S1 thereof is greater than the threshold voltage, and the connection can be made.

Optionally, as shown in fig. 3, the handset control circuit further includes: a third resistor R3, the third resistor R3 is connected in series between the DC bias control node O and the DC bias voltage terminal VBST; the third transistor Q3 and the third transistor Q3 are connected in series between the dc bias control node O and the ground terminal.

Specifically, the drain of the third transistor Q3 is electrically connected to the dc bias control node O, the source of the third transistor Q3 is grounded, and the gate of the third transistor Q3 is electrically connected to the control signal, when the third transistor Q3 is controlled to be turned off, the first transistor Q1 and the second transistor Q2 can be controlled to be turned on by the dc bias voltage provided by the dc bias voltage terminal VBST, the third resistor R3 and the first following unit 61, that is, the smart power amplifier module 1 and the handset 3 are controlled to be turned on, and the handset 3 is driven by the smart power amplifier module 1; when the intelligent power amplifier module 1 and the receiver 3 need to be controlled to be turned off, the third transistor Q3 can be controlled to be turned on by the control signal, and even if the voltage of the dc bias control node O is pulled low, the first transistor Q1 and the second transistor Q2 can be controlled to be turned off.

Alternatively, as shown IN fig. 3, the codec 2 includes a first output terminal P2 and a second output terminal N2, and the handset 3 includes a first input terminal IP and a second input terminal IN; the second switching device unit 52 includes a fourth transistor Q4 and a fifth transistor Q5, the fourth transistor Q4 and the fifth transistor Q5 are N-type MOSFETs, a source S4 of the fourth transistor Q4 is electrically connected to the first output terminal P2 of the codec 2, a drain D3 of the fourth transistor Q4 is electrically connected to the first input terminal IP of the handset 3, a source S5 of the fifth transistor Q5 is electrically connected to the second output terminal N2 of the codec 2, and a drain D5 of the fifth transistor Q5 is electrically connected to the second input terminal IN of the handset 3; the second follower unit 62 includes: a third capacitor C3, the third capacitor C3 is connected in series between the source S4 and the gate G4 of the fourth transistor Q4; a fourth resistor R4, the fourth resistor R4 is connected in series between the gate G4 of the fourth transistor Q4 and the first dc bias control terminal V1; a fourth capacitor C4, the fourth capacitor C4 is connected in series between the source S5 and the gate G5 of the fifth transistor Q5; a fifth resistor R5, a fifth resistor R5 is connected in series between the gate G5 of the fifth transistor Q5 and the second dc bias control terminal V2.

Specifically, the first dc bias control terminal V1 and the second dc bias control terminal V2 may be the same voltage terminal for providing the same signal, or may be different voltage terminals. The voltage signal provided by the first dc bias control terminal V1 may control the fourth transistor Q4 to be turned on or off, and similarly, the voltage signal provided by the second dc bias control terminal V2 may control the fifth transistor Q5 to be turned on or off. When the fourth transistor Q4 and the fifth transistor Q5 are controlled to be turned on, the first dc bias control terminal V1 and the second dc bias control terminal V2 provide a dc bias voltage, and cooperate with the action of the second follower unit 62, so that in the process that the output signal of the codec 2 is transmitted to the handset 3 through the fourth transistor Q4 and the fifth transistor Q5, the voltage difference between the gate G4 and the source S4 of the fourth transistor Q4 is kept unchanged, i.e., the on-resistance is kept unchanged, and the voltage difference between the gate G5 and the source S5 of the fifth transistor Q5 is kept unchanged, i.e., the on-resistance is kept unchanged, thereby reducing the analog signal fluctuation caused by the transistor on-resistance change, and improving the sound quality.

Optionally, as shown in fig. 3, the earpiece control circuit further includes: a sixth resistor R6 and a seventh resistor R7, the sixth resistor R6 is connected in series between the source S4 of the fourth transistor Q4 and the ground terminal, and the seventh resistor R7 is connected in series between the source S5 of the fifth transistor Q5 and the ground terminal.

Specifically, when the smart power amplifier module 1 drives the earpiece 3, the first transistor Q1 and the second transistor Q2 are turned on, the fourth transistor Q4 and the fifth transistor Q5 are turned off, the smart power amplifier module 1 outputs a PWM signal, and the PWM signal may be induced to the codec 2 side through the fourth transistor Q4 and the fifth transistor Q5, in this embodiment, the signal induced to the codec 2 side by the PWM signal through the fourth transistor Q4 and the fifth transistor Q5 may be filtered out through the grounded sixth resistor R6 and the seventh resistor R7.

Optionally, as shown in fig. 3, the earpiece control circuit further includes: a fifth capacitor C5, the fifth capacitor C5 being connected in series between the gate G1 of the first transistor Q1 and the first input IP of the handset 3; a sixth capacitor C6 and a sixth capacitor C6 are connected IN series between the gate G2 of the second transistor Q2 and the second input IN of the handset 3.

Specifically, when the codec 2 drives the handset 3, since the codec 2 outputs a negative voltage, even if the third transistor Q3 pulls down the voltage of the gate G1 of the first transistor Q1 and the voltage of the gate G2 of the second transistor Q2, the first transistor Q1 and the second transistor Q2 may be turned on, and therefore, in the embodiment of the present application, the voltage of the gate G1 of the first transistor Q1 and the voltage of the gate G2 of the second transistor Q2 may be pulled lower by the functions of the fifth capacitor C5 and the sixth capacitor C6, so as to ensure that the first transistor Q1 and the second transistor Q2 are turned off.

For example, the resistances of the first resistor R1, the second resistor R2, the third resistor R3, the sixth resistor R6 and the seventh resistor R7 are all 4.7K Ω, the resistances of the fourth resistor R4 and the fifth resistor R5 are all 37.4K Ω, the capacitances of the first capacitor C1, the second capacitor C2, the fifth capacitor C5 and the sixth capacitor C6 are all 100nF, and the capacitances of the fourth capacitor C4 and the fifth capacitor C5 are all 4.7nF, so as to collectively explain the operation of the handset control circuit according to the structure shown in fig. 3. When the stereo function is implemented, the first transistor Q1 and the second transistor Q2 are controlled to be turned on, the third transistor Q3, the fourth transistor Q4 and the fifth transistor Q5 are turned off, the smart power amplifier module 1 outputs a PWM signal to the handset 3 to drive the handset 3, for example, as shown in fig. 4, fig. 4 is a simulation diagram of drain and gate voltages of the first transistor in fig. 3, the PWM signal output by the first output terminal P1 of the smart power amplifier module 1 is PWM1 in fig. 4, the PWM1 is a pulse, the high voltage is 10V, the low voltage is 0V, the dc bias voltage terminal VBST outputs 10V dc voltage, due to the actions of the first capacitor C1, the first resistor R1 and the third resistor R3, the gate G1 voltage of the first transistor Q1 is 1.5 times the source S1 voltage, the gate G1 voltage of the first transistor Q1 is the PWM2 in fig. 4, the PWM2 is also the pulse, and the PWM 735 is superimposed on the PWM1, i.e., the signals of 5V to 10V, ensure that the voltage difference between the gate G1 and the source S1 of the first transistor Q1 is 5V, i.e., ensure that the first transistor Q1 is turned on, and the second transistor Q2 is turned on similarly. When the proximity sensor function is implemented, the third transistor Q3 is controlled to be turned on, the gate voltages of the first transistor Q1 and the second transistor Q2 are pulled low, the first transistor Q1 and the second transistor Q2 are turned off, the fourth transistor Q4 and the fifth transistor Q5 are controlled to be turned on through the first dc bias control terminal V1 and the second dc bias control terminal V2, at this time, the first dc bias control terminal V1 and the second dc bias control terminal V2 both provide dc bias voltages, the first output terminal P2 and the second output terminal N2 of the codec 2 output analog signals, and due to the action of the second follower unit 62, a voltage difference between the gate G4 and the source S4 of the fourth transistor Q4 is kept constant, the on impedance of the fourth transistor Q4 is kept constant, distortion of the analog headphone signals is suppressed, the analog signals are transmitted to the headphone 3 through the fourth transistor Q4 and the fifth transistor Q5, that is implemented as a headphone driving signal driving device for driving a headphone 2, the earpiece 3 may be driven to emit ultrasonic waves to perform the function of a proximity sensor.

The embodiment of the application further provides a terminal, which comprises the earphone control circuit. The specific structure and principle of the receiver control circuit are the same as those of the above-mentioned embodiment, and are not described herein again, the receiver 3 is used for converting an audio electrical signal into a sound signal, and when the terminal answers a call or voice information, the receiver 3 can be close to the ear of a person to answer the voice. The terminal in the embodiment of the application can be an electronic device such as a mobile phone.

In the embodiments of the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, and means that there may be three relationships, for example, a and/or B, and may mean that a exists alone, a and B exist simultaneously, and B exists alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" and similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, at least one of a, b, and c may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.