WO2019114297A1

WO2019114297A1 - Bias voltage output circuit and driving circuit

Info

Publication number: WO2019114297A1
Application number: PCT/CN2018/099433
Authority: WO
Inventors: 张洵; 李勇; 舒迎飞; 王浩
Original assignee: 华为技术有限公司
Priority date: 2017-12-13
Filing date: 2018-08-08
Publication date: 2019-06-20

Abstract

A bias voltage output circuit and a driving circuit. The bias voltage output circuit comprises: a bias voltage output module, used to output a bias voltage under the action of a logic control module and the bias voltage is used to drive an audio output device; a filter capacitor, used to filter noise generated by the bias voltage output module and store power produced during the process of the bias voltage output module outputting a bias voltage; a bleeder module, used to discharge the power stored by the filter capacitor under the action of a logic control module; a logic control module, used, when it is ascertained that the audio output device has connected to an audio playback device, to trigger the bias voltage output module to output a bias voltage and to control the bleeder module to prevent discharge of the power stored by the filter capacitor. When it is ascertained that the audio output device is disconnected from the audio playback device, triggering the bias voltage output module to stop outputting bias voltage and controlling the bleeder module to discharge the power stored by the filter capacitor.

Description

Bias voltage output circuit and driving circuit

Technical field

The present application relates to the field of communications technologies, and in particular, to a bias voltage output circuit and a driving circuit.

Background technique

Terminal devices are showing more and more functions in the process of rapid development. The use of terminal devices to play audio files or video files has become a part of everyday life. For example, a user can play an audio file and listen by inserting a headset into the headset socket of the terminal device.

When the earphone is plugged and unplugged, the DC level of the terminal device will jump, resulting in pop noise and the like. And due to the human body's own actions or contact, separation and friction with other objects, it also brings electrostatic-static discharge (ESD) problems to the terminal equipment. When a user misuses, for example, plugging a charger plug into a headphone jack, it also creates an electrical over-stress (EOS) problem that can cause permanent failure of the internal chip of the terminal device. Therefore, how to improve the above problems is an urgent need for the terminal equipment to be solved.

In the terminal device, the MICBIAS chip for powering the earphone is most susceptible to the above problems, thus solving the blasting sound, ESD and EOS of the MICBIAS chip during the plugging and unplugging process of the earphone. The problem is to solve the above problems of the terminal device.

Please refer to FIG. 1 , which is a solution for eliminating popping sound in the prior art. After detecting that the earphone is pulled out, the voltage on the filter capacitor C1 of the MICBIAS chip is quickly discharged through the switch S2 in FIG. 1, and the earphone is divided by the switch S1, so that the earphone can be recognized by the human ear. The sound should be kept to a minimum. However, since the switch S1 directly contacts the headphone interface, the ESD can be directly applied to the switch S1 through the MICP, which in turn causes ESD and EOS problems of the MICBIAS chip.

It can be seen that in the prior art, the popping sound, ESD and EOS problems of the external audio output device during the plugging and unplugging process cannot be simultaneously solved.

Summary of the invention

Embodiments of the present application provide a method for simultaneously solving popping sound, ESD, and EOS problems.

In a first aspect, a bias voltage output circuit of an audio playback device is provided. The bias voltage output circuit includes a bias voltage output module, a logic control module, a filter capacitor, and a bleeder module. a bias voltage output module, the first end of the bias voltage output module is connected to the first output end of the logic control module, and the second end is connected to an interface of the external audio output device of the audio playback device, Under the action of the logic control module, an output bias voltage is used to drive an external audio output device connected to the interface; the filter capacitor is connected to the bias voltage output module for filtering the offset The voltage output module generates noise during the output of the bias voltage, and stores the power during the output of the bias voltage output module; the first end of the bleeder module is connected to the filter capacitor, The second end is connected to the second output end of the logic control module, and is configured to discharge the power stored by the filter capacitor under the action of the logic control module; the logic control module is configured to determine the access of the external audio output device When the interface is connected, the bias voltage output module is triggered to output the bias voltage, and the bleeder module is controlled to ban the storage of the storage capacity of the filter capacitor. When given the external audio output device connected to the interface is disconnected, the trigger bias voltage output module outputting the bias voltage is stopped, and controlling the discharge of the filter capacitor discharging module bleed charge stored.

In the above technical solution, when the logic control module detects that the external audio output device is disconnected from the audio playback device, the control bias voltage output module stops outputting the bias voltage, so that the external audio output device is disconnected from the power source. At the same time, the bleeder and discharge module is controlled to discharge the power stored in the filter capacitor, so that the blasting sound does not appear in the external audio output device, thereby solving the problem of blasting sound. Further, in the circuit, the logic control module is respectively connected to the bias voltage output module and the bleeder and discharge module, and the problem of the blasting sound can be solved by controlling the states of the bias voltage output module and the bleeder and discharge module respectively, thereby no longer As in the prior art, for example, the solution described in FIG. 1 requires the switch S1 to be provided in the circuit, and naturally there is no ESD of the MICBIAS chip caused by static electricity or external voltage directly hitting the switch S1 through the MICP in the prior art. And EOS issues. In the circuit, the venting and discharging module is not directly connected to the interface of the external audio output device, so that the static electricity or the external voltage can be prevented from being directly discharged by the MICP, and the external audio output device can be solved in the prior art. MICP causes ESD and EOS problems with the bias voltage output circuit, ie, both POP, ESD, and EOS issues are addressed.

In a possible design, the bias voltage output module includes a voltage generating module, an error amplifying module, a first driving module, and an output voltage sampling and feedback module, and an output end of the voltage generating module and the first of the error amplifying module The input terminal is connected, the voltage generating module is configured to generate a reference voltage, and output the reference voltage to the error amplifying module, the output end of the error amplifying module is connected to the input end of the first driving module, and the error amplifying module is used to The reference voltage is subjected to a voltage stabilization process to obtain and output the bias voltage to the first driving module, and an output end of the first driving module is connected to the external audio output device, and the external audio output is driven by the bias voltage The input end of the output voltage sampling and feedback module is connected to the output end of the first driving module, and the output end is connected to the second input end of the error amplifying module, and the output voltage sampling and feedback module is used for the offset The voltage is sampled, and the sampling result is fed back to the error amplification module, and the error amplification module is used according to Adjusting the reference voltage sampling result.

In the above technical solution, the bias voltage output module is realized by a simple structure such as a voltage generating module, an error amplifying module, a first driving module, and an output voltage sampling and feedback module, and the implementation manner is simple.

In a possible design, the bias voltage output module includes a voltage generating module, an error amplifying module, a class AB level shifting control module, a second driving module, and an output voltage sampling and feedback module, and an output terminal of the voltage generating module Connected to the first input end of the error amplifying module, the voltage generating module is configured to generate a reference voltage, and output the reference voltage to the error amplifying module, the output end of the error amplifying module and the class AB level conversion control module The input terminal is connected, and the error amplifying module is configured to perform voltage stabilization processing on the reference voltage, and obtain and output an adjusted voltage to the class AB level conversion control module, and the output end of the class AB level conversion control module and the first The input end of the two driving module is connected to convert the adjusted voltage into the bias voltage, and output the bias voltage to the driving module, where the noise of the bias voltage is less than the noise of the adjusted voltage, The output end of the second driving module is connected to the external audio output device for driving the external audio output device through the class AB control level signal The input end of the output voltage sampling and feedback module is connected to the output end of the second driving module, and the output end is connected to the second input end of the error amplifying module, and the output voltage sampling and feedback module is used for the biasing The voltage is sampled, and the sampling result is fed back to the error amplification module, and the error amplification module is configured to adjust the reference voltage according to the sampling result.

In the above technical solution, the noise of the class AB control signal is small and the distortion rate is low, and the class AB level conversion control module is added in the bias voltage output module, and the voltage is generated by the class AB level conversion control module. The reference voltage generated by the module is converted into a class AB level signal, which can reduce the noise of the bias voltage output circuit and make the bias voltage outputted by the bias voltage output circuit more stable.

In a possible design, the bias voltage output circuit further includes a first filter resistor coupled to the second driving module for filtering out time division multiplexed TDD noise generated in the bias voltage output circuit.

In the above technical solution, the TDD noise in the bias voltage output circuit can be further reduced by adding a filter resistor to the bias voltage output circuit.

In a possible design, the bias voltage output module comprises a voltage generating module, an error amplifying module, a bidirectional switch, a third driving module, a class AB level conversion control module, a fourth driving module, and an output voltage sampling and feedback module. The output end of the voltage generating module is connected to the first input end of the error amplifying module, the voltage generating module is configured to generate a reference voltage, and output the reference voltage to the error amplifying module, the output end of the error amplifying module The input end of the bidirectional switch is connected, the first output end of the bidirectional switch is connected to the third driving module, and the second output end of the bidirectional switch is connected to the class AB level conversion control module, and the bidirectional switch and the bidirectional switch When the first output end forms the first path, the error amplifying module is configured to perform voltage stabilization processing on the reference voltage, obtain and output the bias voltage to the third driving module, where the bidirectional switch and the bidirectional switch When the second output forms a second path, the error amplifying module is configured to perform voltage stabilization processing on the reference voltage to obtain and report to the class AB The switching control module outputs the adjusted voltage, and the bidirectional switch is connected to the logic control module, and is configured to select or form the second path by the logic control module, and the output end of the third driving module Connecting to the external audio output device, when the bidirectional switch forms the first path, driving the external audio output device by the bias voltage, the output end of the class AB level conversion control module and the fourth driving module The input terminal is connected to convert the adjusted voltage into the bias voltage when the bidirectional switch forms the second path, and output the bias voltage to the fourth driving module, the noise of the bias voltage The output of the fourth driving module is connected to the external audio output device, and is configured to drive the external audio output device by the bias voltage when the bidirectional switch forms the second path, An input end of the output voltage sampling and feedback module is respectively connected to an output end of the third driving module and an output end of the fourth driving module, and outputs The terminal is connected to the second input end of the error amplifying module, and the output voltage sampling and feedback module is configured to sample the bias voltage, and feed back the sampling result to the error amplifying module, and the error amplifying module is configured to The sampling result adjusts the reference voltage.

In the above technical solution, the bias voltage output module can output the bias voltage in any of two ways, and add a bidirectional switch in the bias voltage output module, so that any one of them can be selected according to actual use requirements. One way to achieve the bias voltage output is to increase the flexibility of the bias voltage output module.

In a possible design, the bias voltage output circuit further includes a second filter resistor coupled to the fourth driving module for filtering out time division multiplexed TDD noise generated in the bias voltage output circuit.

In a possible design, the bias voltage output module further includes an electrostatic discharge/over-electric stress protection module coupled to the input of the output voltage sampling and feedback module for presence in the bias voltage output circuit In the case of excessive electrical stress or static electricity, the voltage across at least one of the plurality of modules included in the bias voltage output module is reduced, and the at least one module does not include the electrostatic discharge/over-electric stress protection module.

In the above technical solution, when an ESD/EOS event is generated in the bias voltage output circuit, the electrostatic discharge/over-electric stress protection module can ensure that the voltage across the bias voltage output module is within a safe value, thereby effectively protecting Each module in the bias voltage output module is protected from transient high voltage surges.

In one possible design, the bleeder module is an N-type metal-oxide-semiconductor transistor or a unidirectional switch.

In one possible design, the second drive module is a P-type metal-oxide-semiconductor transistor or an N-type metal-oxide-semiconductor transistor.

In the above technical solution, the bleeder and discharge module and the second drive module can be realized by simple components, and the implementation is simple.

In a second aspect, a driving circuit for an audio output device is provided, the driving circuit comprising a processing module, a crosstalk canceling module, a digital to analog conversion module, and a driving module. The output end of the processing module is connected to the input end of the crosstalk cancellation module, and is configured to generate and output an audio signal to the crosstalk cancellation module, where the audio signal includes a left channel signal and a right channel signal, the crosstalk cancellation module, the output end and the The input end of the digital-to-analog conversion module is connected to cancel the crosstalk between the left channel signal and the right channel signal, and output the left-channel signal after the crosstalk cancellation and the right-path signal after the crosstalk is eliminated to the digital-to-analog conversion module; The digital-to-analog conversion module is connected to the input end of the driving module, and is configured to perform digital-to-analog conversion processing on the left-channel signal after eliminating crosstalk, obtain and output a left-channel analog audio signal to the driving module, and The right channel signal after crosstalk cancellation is subjected to digital-to-analog conversion processing, and a right-channel analog audio signal is obtained and output to the driving module; the output module is connected to the external audio output device for driving the left end of the external audio output device The output device outputs the left analog audio signal, and the right output device that drives the external audio output device outputs the right analog sound Signal.

In the above technical solution, by intercepting the audio signal transmission path of the processing module to the digital-to-analog conversion module, a crosstalk cancellation module is added to the path, and the left channel signal and the right channel signal are correlated by the crosstalk cancellation module. The crosstalk between the left and right signals finally outputted by the external audio output device is reduced, and the left and right crosstalk performance of the output signal of the external audio output device in the prior art can be improved.

In one possible design, the crosstalk cancellation module includes a first enhancement device, a first delay device, a first computing device, a second enhancement device, a second delay device, and a second computing device. The first reinforcing device is configured to filter out a first portion of the left channel signal of the left channel signal that is outside the preset frequency band, and according to a preset amplification factor, the second portion of the left channel signal that is located on the preset frequency band is left The road signal is amplified to obtain a first left channel signal, the first delay device is configured to acquire a left channel signal within a preset number of sampling periods before the current sampling period, and the first computing device is configured to use the left channel signal The second partial left signal and the left signal in the preset number of sampling periods before the current sampling period are subjected to a first operation to obtain the processed left signal; the second boosting device is used for filtering a first portion of the right channel signal outside the preset frequency band of the right channel signal, and amplifying the second portion of the right channel signal of the right channel signal on the preset frequency band according to the preset amplification factor, to obtain the first a right channel signal; the second delay device is configured to acquire a right channel signal in the preset number of sampling periods before the current sampling period, and the second computing device is configured to use the right channel signal, the second portion The right signal and the right signal within the sampling period preceding the current sampling period of the predetermined number of a first calculation to obtain the right signal after the processing.

In the above technical solution, the crosstalk between the left channel signal and the right channel signal can be reduced by filtering, sampling, and processing the left channel signal and the right channel signal, respectively, and the implementation manner is simple.

In a possible design, the driving circuit further includes an impedance detecting module, an input end of the impedance detecting module is connected to an output end of the driving module, and an output end is connected to the processing module, and the impedance detecting module is configured to detect the external connection The impedance of the audio output device is output to the processing module; the processing module is further configured to adjust the voltage of the audio signal according to the impedance.

In the above technical solution, the impedance of the external audio output device is detected by the impedance detecting module, and then the impedance value is output to the processing module, so that the processing module can output an audio signal whose voltage value matches the external audio output device, and increase the driving circuit. Flexibility.

In a possible design, the driving circuit further includes a correction module, the input end of the correction module is connected to the output end of the driving device, and the output end is connected to the crosstalk canceling module, and the correcting module is configured to detect the left side analog Stereo separation between the audio signal and the right analog audio signal, and outputting the stereo separation to the crosstalk cancellation module; the crosstalk cancellation module is further configured to adjust the first enhancement device or the first according to the stereo separation degree The value of the preset amplification factor in the second enhancement device, and/or the preset number of values in the first delay device or the second delay device.

In the above technical solution, the stereo separation degree between the output left analog audio signal and the right analog audio signal is detected in real time by the correction module, so that the crosstalk cancellation module can adjust the internal processing according to the detected stereo separation degree. Parameters, for example, when the stereo separation degree is small, increasing the amplification system in the enhancement device, reducing the sampling period of the delay device, etc., the drive circuit can be adapted to different audio playback devices, and the application range of the drive circuit can be improved. .

DRAWINGS

1 is a circuit diagram of a solution for eliminating popping sound in the prior art;

2 is a schematic diagram of a bias voltage output circuit according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a first implementation manner of a bias voltage output module 301 according to an embodiment of the present application;

4 is a schematic diagram of a second implementation manner of the bias voltage output module 301 according to an embodiment of the present application;

FIG. 5 is a schematic structural diagram of a class AB amplifier according to an embodiment of the present application; FIG.

FIG. 6 is a schematic diagram of a third implementation manner of the bias voltage output module 301 according to an embodiment of the present application;

7A is a schematic diagram of a first implementation manner of a bidirectional switch 703 according to an embodiment of the present application;

FIG. 7B is a schematic diagram of a second implementation manner of the bidirectional switch 703 according to the embodiment of the present application;

8A is a schematic diagram of a first connection manner of an electrostatic discharge/over-electric stress protection module 901 according to an embodiment of the present application;

FIG. 8B is a schematic diagram of a second connection manner of the electrostatic discharge/over-electric stress protection module 901 in the embodiment of the present application;

8C is a schematic diagram of a third connection manner of the electrostatic discharge/over-electric stress protection module 901 in the embodiment of the present application;

FIG. 9 is a schematic structural diagram of an electrostatic discharge/over-electric stress protection module 901 according to an embodiment of the present application;

FIG. 10 is a schematic structural diagram of a detection module in a logic control module 302 according to an embodiment of the present application;

FIG. 11 is a schematic structural diagram of a bleeder and discharge module 304 according to an embodiment of the present application;

12A is a schematic diagram of a first connection manner of a filter resistor 305 according to an embodiment of the present application;

12B is a schematic diagram of a second connection manner of the filter resistor 305 according to an embodiment of the present application;

13 is a schematic diagram of a specific example of a bias voltage output circuit in an embodiment of the present application;

14A is a schematic structural diagram of an earphone adopting the OMTP standard system in the prior art;

14B is a schematic structural diagram of an earphone using a CTIA standard system in the prior art;

15 is a schematic diagram showing a connection manner of a set of analog switches added between wires connected to a microphone and a headphone in a headphone socket when the earphone adopts the USB Type-C standard system in the prior art;

16 is a schematic diagram of crosstalk of left and right signals of a prior art earphone during transmission;

FIG. 17 is a schematic structural diagram of a driving circuit of an audio output device according to an embodiment of the present disclosure;

FIG. 18 is a schematic structural diagram of an implementation manner of a crosstalk cancellation module 1802 according to an embodiment of the present application;

FIG. 19 is a schematic structural diagram of an implementation manner of a driving circuit in an embodiment of the present application;

20 is a schematic structural diagram of another implementation manner of a driving circuit in an embodiment of the present application;

FIG. 21 is a schematic structural diagram of an implementation manner of the correction module 1806 in the embodiment of the present application.

Detailed ways

The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

Hereinafter, some of the terms in the embodiments of the present application will be explained so as to be understood by those skilled in the art.

(1) Plosive sound: refers to a transient audio signal generated on an external audio playback device when an external audio playback device, such as a headphone or a speaker, is used to play the sound. This plosive sound is mainly caused by a jump in the DC level of the playback device connected to the external audio playback device, and generally exists in the following two application scenarios: the system (or chip) of the playback device is normal (or Abnormal) power-on and power-off process, and the connection (or disconnection) of the playback device to the external audio playback device. In the embodiment of the present application, the problem of popping sound generated during the connection (or disconnection) between the playback device and the external audio playback device is mainly solved.

(2) Electrostatic discharge: Refers to the damage caused by the instantaneous discharge of the device when it is subjected to static electricity generated by itself or other external devices. Static electricity is an objective natural phenomenon, such as contact, friction, and electrical induction. The body's own actions or contact, separation and friction with other objects can generate thousands or even tens of thousands of volts of static electricity. The general chip's ESD protection standard is only two thousand volts, so the static electricity generated by the human body often causes electrons. Electrical products are unstable or even damaged.

(3) Excessive electrical stress: When the voltage or current outside the device is too high, exceeding the maximum specification of the voltage or current that the device can withstand, a thermal effect occurs, resulting in weakened or even damaged performance of the device. Generally speaking, EOS refers to the damage caused by improper design voltage (flow) or leakage current generated by test machine, production machine, instrument, fixture, etc., to other devices.

(4) Time division dual (TDD) noise: For the global system for mobile communication (GSM) communication protocol, the terminal equipment RF power amplifier needs to transmit signals every 4.6 milliseconds (that is, 217 Hz). Communicating with the base station, the signal contains 900MHz/1800MHz, or 1900MHz GSM signal and the envelope of the power amplifier. When the receiving signal is not good, the terminal device will increase the transmitting power, causing interference with the microphone for picking up the sound inside the terminal device, and the earpiece or earphone for playing the sound. The result reflected by the interference is: when the terminal device When the caller plays a ring tone, or in an application scenario such as making a voice call or playing a short message tone, the current sound of “哼哼” or “嗡嗡” will be heard in the microphone or earphone.

(5) External audio output device: It can be a device such as a headphone, a speaker or a speaker. The earphones may be earphones of the Open Terminal Equipment Platform Organization (OMTP) standard system, or may be the headphones of the American Wireless Communications and Internet Association (CTIA) standard system, or may be headphones adopting the USB Type-C standard system. It can also be other standard headphones in the development of future communication technologies.

(6) Audio playback device: It can be a device that needs to play audio, such as a terminal device, a computer, a hearing aid, or a virtual reality device. Wherein, the terminal device may be a device including providing voice and/or data connectivity to the user, for example, may include a handheld device having a wireless connection function, or a processing device connected to the wireless modem. The terminal device can communicate with the core network via a radio access network (RAN) to exchange voice and/or data with the RAN. The terminal device may include a user equipment (UE), a wireless terminal device, a mobile terminal device, a mobile phone (or "cellular" phone), a portable, a pocket, a handheld, a computer built-in or a mobile device. , smart wearable devices, etc. For example, personal communication service (PCS) phones, cordless phones, Session Initiation Protocol (SIP) phones, smart helmets, and the like.

(7) Stereo Separation: Characterizes the degree of crosstalk between the left and right channels of the audio output device. The greater the crosstalk between the two channels, the smaller the stereo separation.

The term "and/or" in this context is merely an association describing the associated object, indicating that there may be three relationships, for example, A and / or B, which may indicate that A exists separately, and both A and B exist, respectively. B these three situations. In addition, the character "/" in this article, unless otherwise specified, generally indicates that the contextual object is an "or" relationship.

In the prior art, in the solution shown in FIG. 1, the problem of the popping sound generated during the insertion and removal of the earphone is solved by the switch S1 and the switch S2, but since the switch S1 is directly connected to the earphone interface, when the switch S1 is at In the connection state, and the terminal device generates static electricity due to factors such as friction, induction between electronic devices, or the charger of the terminal device using excessive voltage, the MICBIAS chip forming a loop with the switch S1 may be due to the static electricity or the charger. The discharge causes the ESD or EOS problem. It can be seen that the bias voltage output circuit used in the prior art for providing the bias voltage to the external audio output device cannot simultaneously solve the popping sound, ESD and the external audio output device during the plugging and unplugging process. EOS problem.

In view of this, the embodiment of the present application provides a bias voltage output circuit of an audio playback device for simultaneously solving POP, ESD, and EOS problems.

In the following, the technical solution provided by the embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, an audio playback device as a terminal device and an external audio output device as an earphone will be taken as an example for description.

Please refer to FIG. 2 , which is a bias voltage output circuit according to an embodiment of the present application. The bias voltage output circuit includes a bias voltage output module 301 , a logic control module 302 , a filter capacitor 303 , and a bleeder module 304 . The bias voltage output module 301 is connected to the earphone interface on the terminal device. When the user of the terminal device inserts the earphone into the earphone jack on the terminal device, the logic control module 302 is connected to the earphone, and the logic control module 302 detects The insertion operation then triggers the bias voltage output module 301 connected to the first output terminal of the logic control module 302 to output a bias voltage. At this time, the bias voltage of the earphone outputted by the bias voltage output module 301 is applied. Under work. When the earphone is in an operating state, the filter capacitor 303 connected to the bias voltage output module in the bias voltage output circuit is used to filter out the bias voltage output module 301 generated during the output of the bias voltage required by the earphone. The noise is stored in the process of outputting the bias voltage by the bias voltage output module 301; when the user of the terminal device pulls the earphone out of the earphone jack, the earphone is disconnected from the terminal device, and the logic control module 302 detects the The pull-out operation then triggers the bias voltage output module 301 to stop outputting the bias voltage, and at the same time, the logic control module 302 controls the bleeder module 304 connected to the second output terminal to discharge the amount of power stored in the filter capacitor 303 to avoid filtering. The plosive sound caused by the residual voltage in the capacitor 303.

Further, in the circuit, the logic control module 302 is respectively connected to the bias voltage output module 301 and the bleeder module 304, and the blowdown can be solved by controlling the states of the bias voltage output module 301 and the bleeder module 304, respectively. The problem is that, unlike the prior art, for example, the solution described in FIG. 1, it is necessary to provide the switch S1 in the circuit, and naturally there is no prior art due to static electricity or an external voltage directly hitting the switch S1 through the MICP. The ECD and EOS problems of the MICBIAS chip, and in the circuit, the bleeder module 304 is not directly connected to the interface of the external audio output device in the audio playback device, thereby avoiding the leakage of static electricity or external voltage directly through the MCP. The discharge module can solve the ESD and EOS problems of the bias voltage output circuit caused by the MCP of the external audio output device in the prior art, that is, solve the POP, ESD and EOS problems at the same time.

In practical applications, the bias voltage output module 301 can adopt various implementation manners, for example, including but not limited to the following three types:

The first way to achieve:

Referring to FIG. 3, the bias voltage output module 301 includes a voltage generating module 401, an error amplifying module 402, a first driving module 403, and an output voltage sampling and feedback module 404, wherein:

An output end of the voltage generating module 401 is connected to the first input end of the error amplifying module 402. The voltage generating module 401 is configured to generate a reference voltage, where the value of the reference voltage is a value of a bias voltage required by the earphone, and is generated. The reference voltage is input to the error amplifying module 402; the output of the error amplifying module 402 is connected to the input end of the first driving module 403, and the error amplifying module 402 is used for voltage stabilizing the reference voltage, outputting a bias voltage, and The bias voltage is output to the first driving module 403; the output end of the first driving module 403 is connected to the interface of the earphone, and is used to drive the earphone into the working state through the bias voltage when the earphone is connected to the interface; The input end of the sampling and feedback module 404 is connected to the output end of the first driving module 403, and the output end of the output voltage sampling and feedback module 404 is connected to the second input end of the error amplifying module 402 for sampling the bias voltage. And the sampling result is fed back to the error amplification module 402, and the error amplification module 402 adjusts the voltage value of the reference voltage according to the sampling result.

In a practical application, the voltage generation module 401 can be a voltage reference source. When selecting the voltage reference source, it is necessary to consider the bias voltage required by the earphone and the resolution accuracy and operating temperature range required by the output circuit. The voltage reference source can be divided into a bandgap voltage reference source and a Zener voltage reference source. The bandgap voltage reference source structure is a series connection of a forward biased PN junction and a voltage source having a thermoelectric potential (VT), which is compensated by the negative temperature coefficient of the PN junction and the positive temperature coefficient of the VT, thereby outputting a temperature A stable reference voltage. The voltage regulator reference voltage is constructed by connecting a Zener diode with a subsurface breakdown in series with a PN junction, and the temperature is compensated by the positive temperature coefficient of the Zener diode and the negative temperature coefficient of the PN junction, so that the output is stable. The reference voltage. Generally speaking, the voltage reference of the Zener voltage reference source is higher, about 7V, and the reference voltage of the bandgap voltage reference source is relatively low. Therefore, in actual use, the bias voltage required by the earphone can be used. Select the appropriate type of voltage reference source. Of course, you can also use the reference voltage chip directly, for example, the MAX6350 chip, the MAX675 chip, etc., and will not be described here.

The error amplification module 402 can be an error amplifier (EA). The error amplifier works by comparing the difference between the voltages input at both ends, wherein the voltage input to one input terminal is the reference voltage generated by the voltage generating module 401, and the voltage at the other input terminal is the preset reference voltage, thereby obtaining the The difference signal of the two voltages is output to the gate of the adjustment tube inside the error amplifier, controls the operating state of the adjustment tube, and corrects the pulse duty ratio of the voltage, so that the voltage outputted by the error amplifier remains stable. In actual use, the error amplifying module 402 may be an error amplifying circuit formed by selecting a corresponding device by the above working principle, or may be an error amplifier chip, such as a TL431 chip, etc., which is not limited herein.

The first driving module 403 may be composed of a driver or a power tube such as a Power MOS transistor. The size and power of the driver or the power tube need to be determined according to the requirements of the entire circuit and the magnitude of the bias voltage required by the earphone, and are not limited herein.

The output voltage sampling and feedback module 404 can be specifically a sampling circuit. The bias voltage is sampled by the sampling circuit, and the sampling result is fed back to the error amplification module 402. The output voltage sampling and feedback module 404 can directly output the sampling signal of the bias voltage to the error amplifying module 402, so that the error amplifying module 402 determines the control of the output voltage according to the sampling signal, such as increasing the voltage or lowering the voltage; The comparison result of the sampling signal of the bias voltage and a standard voltage may be output to the error amplification module 402. For example, if the difference between the voltage of the sampling signal and the standard voltage is within a preset range, the output is low, if sampling When the difference between the voltage of the signal and the standard voltage exceeds the preset range, the high level is output, and thus the error amplifying module 402 directly controls the output voltage according to the comparison result. Of course, other feedback methods may also be used by those skilled in the art, which are not limited herein.

In order to reduce the noise of the bias voltage output circuit, the bias voltage outputted by the bias voltage output circuit is more stable. The second embodiment of the bias voltage output module 301 is provided in the embodiment of the present application:

Referring to FIG. 4, the bias voltage output module 301 includes a voltage generating module 501, an error amplifying module 502, a class AB level shift control module 503, a second driving module 504, and an output voltage sampling and feedback module 505, wherein:

An output end of the voltage generating module 501 is connected to the first input end of the error amplifying module 502, and the voltage generating module 501 is configured to generate a reference voltage, where the value of the reference voltage is a value of a bias voltage required by the earphone, and is generated. The reference voltage is input to the error amplification module 502; the output of the error amplification module 502 is connected to the input of the class AB level conversion control module 503, and the error amplification module 502 is used for voltage regulation of the reference voltage, and the output is adjusted. And adjusting the voltage to the class AB level conversion control module 503; the output of the class AB level conversion control module 503 is connected to the input end of the second driver module 504 for using the adjusted voltage The conversion is converted to a bias voltage, and the bias voltage is output to the second driving module 504. In this implementation, the type of the bias voltage is a class AB control level signal, and the TDD noise of the class AB control level signal is less than the TDD noise of the adjusted voltage; the output of the second driving module 504 is The earphone is connected to drive the earphone into an operating state by the bias voltage; the input end of the output voltage sampling and feedback module 505 is connected to the output end of the second driving module 504, and the output of the output voltage sampling and feedback module 505 is The second input end of the error amplifying module 502 is connected to sample the class AB control level signal, and feed the sampling result to the error amplifying module 502, and the error amplifying module 502 adjusts the voltage of the reference voltage according to the sampling result. value.

In practical applications, the class AB level shift control module 503 can be constructed of a class AB amplifier. The structure of the class AB amplifier is shown in Figure 5, consisting of two transistors Q1 and Q2, and adding two identical V _BB voltages between transistor Q1 and transistor Q2. Class AB amplifiers are usually combined with two transistors. The two transistors use a push-pull operation. When a voltage signal is input, one of the two transistors is turned off, and the other transistor is turned on. The two transistors are always turned on. Cut-off and conduction, so that Class AB amplifiers generate less heat and are more efficient.

The output of the class AB amplifier can be a differential output, as shown in FIG. 4, and of course, it can also be a single-ended output. In the embodiment of the present application, a differential output of a class AB amplifier is taken as an example. When the class AB amplifier is a differential output, the driving module 504 may be composed of two drivers or two power transistors. For example, the second driving module 504 includes two metal-oxide-semiconductor transistors, one of which is a P-type metal-oxide. - a semiconductor transistor (pmos tube) and the other an N-type metal-oxide-semiconductor transistor (nmos tube). The size and power of the driver or the power tube need to be determined according to the requirements of the entire circuit and the magnitude of the bias voltage required by the earphone, and are not limited herein.

In a practical application, the voltage generating module 501, the error amplifying module 502, and the output voltage sampling and feedback module 505 are similar to the voltage generating module 401, the error amplifying module 402, and the output voltage sampling and feedback module 404 in the first implementation manner, respectively. I will not repeat them here.

In the two implementation manners of the bias voltage output module 301, the first implementation is simpler, and the bias voltage outputted by the second implementation is more stable, and for the terminal device, different circuit layouts will be There are different requirements for the bias voltage. For example, when the position of the bias voltage output module 301 is located far from the position of the earphone jack, the ground planes of the bias voltage output module 301 and the headphone jack may be inconsistent, so that the terminal device is in communication. In the process, TDD noise is more likely to occur, and the bias voltage is more stable at this time; and when the position of the voltage output module 301 is placed closer to the position of the earphone socket, a simple bias voltage output circuit can be used at this time. To reduce the complexity of the circuit. Therefore, the embodiment of the present application provides a third implementation manner of the bias voltage output module 301:

Referring to FIG. 6, the bias voltage output module 301 includes a voltage generating module 701, an error amplifying module 702, a bidirectional switch 703, a third driving module 704, a class AB level shift control module 705, a fourth driving module 706, and an output voltage sampling. And a feedback module 707, wherein:

An output end of the voltage generating module 701 is connected to the first input end of the error amplifying module 702, and the voltage generating module 701 is configured to generate a reference voltage, where the value of the reference voltage is a value of a bias voltage required by the earphone, and is generated. The reference voltage is input to the error amplifying module 702; the output of the error amplifying module 702 is connected to the input end of the bidirectional switch 703, the first output end of the bidirectional switch 703 is connected to the first driving module 704, and the second output end of the bidirectional switch 703 Connected to the class AB level conversion control module 705, when the first path of the bidirectional switch 703 and the first output end of the bidirectional switch 703 is formed, the error amplifying module 702 is configured to perform voltage stabilization processing on the reference voltage, and output a bias voltage. The bias voltage is output to the third driving module 704. When the second path is formed by the bidirectional switch 703 and the second output end of the bidirectional switch 703, the error amplifying module 702 is configured to perform voltage stabilization processing on the reference voltage, and output adjustment. After the voltage, the adjusted voltage is output to the class AB level conversion control module 705; the bidirectional switch 703 is connected to the logic control module 302 for logic control The first module or the second path is formed by the module 302. The output of the third driving module 704 is connected to the earphone for driving the bias voltage when the bidirectional switch 703 forms the first path. The earphone enters an operating state; an output end of the class AB level shift control module 705 is connected to an input end of the fourth driving module 706, and is configured to convert the adjusted voltage into a bias when the second path is formed by the bidirectional switch 703 Setting a voltage, and outputting the bias voltage to the fourth driving module 706, the type of the bias voltage is a class AB control level signal, and the TDD noise of the class AB control level signal is less than the TDD noise of the adjusted voltage. The output end of the fourth driving module 706 is connected to the earphone for driving the earphone into the working state by the bias voltage; the input end of the output voltage sampling and feedback module 707 is respectively connected with the output end of the third driving module 704 and the fourth The output of the driving module 706 is connected, and the output of the output voltage sampling and feedback module 707 is connected to the second input of the error amplifying module 702 for sampling the bias voltage. And the sampling result is fed back to the error amplifier module 702, a module error amplifier 702 to adjust the reference voltage value based on the sampling result.

In this way, the first implementation mode and the second implementation manner are combined by the bidirectional switch 703. In the specific use process, the technician flexibly selects the first path or the second path output bias voltage according to the use requirement, thereby The bias voltage output module 301 is more suitable for use. Further, when the bias voltage output module 301 outputs the bias voltage using the class AB level shift control module 705, since the class AB control level is more stable, the TDD noise can be improved without adding additional noise reduction capacitors. It is possible to reduce the board area of the terminal device and to facilitate miniaturization of the terminal device.

Of course, in order to enable the bias voltage output module 301 to be more automated, the bidirectional switch 703 in the third implementation can also be controlled using a chip. For example, by programming a software program in the chip, detecting the distance between the bias voltage output module 301 and the earphone socket, when the distance is greater than the preset threshold, the chip controls the bidirectional switch 703 to select the second path when the distance is less than a preset threshold. At this time, the chip controls the bidirectional switch 703 to select the first path, which simplifies the control operation of the bias voltage output module 301 by the technician.

In a practical application, the voltage generating module 701, the error amplifying module 702, the third driving module 704, and the output voltage sampling and feedback module 707 are respectively combined with the voltage generating module 401, the error amplifying module 402, and the first driving in the first implementation manner. The module 403 is similar to the output voltage sampling and feedback module 404, and the class AB level shift control module 705 and the fourth driver module 706 are similar to the class AB level shift control module 503 and the second driver module 504 of the second implementation, respectively. , will not repeat them here.

The bidirectional switch 703 may specifically be a selection switch having two interfaces, and the two interfaces are respectively connected to the third driving module 704 and the class AB level conversion control module 705, as shown in FIG. 7A; or may be composed of multiple switches. For example, the bidirectional switch can be composed of two independent single interface switches, and the third driving module 704 and the class AB level conversion control module 705 are respectively connected to a single interface switch, and which module is used to control the single interface switch guide connected to the module. As shown in Figure 7B. The selection switch or the single-interface switch may be an independent switching device, or may be formed by using a MOS transistor or a logic operation chip. The specific structure of the bidirectional switch 703 is not limited in the embodiment of the present application.

In order to prolong the service life of each device in the bias voltage output module 301 and reduce the probability of damage to each device, in three implementations of the bias voltage output module 301, an electrostatic discharge/over-electric stress protection module 901 may also be disposed. , as shown in Figures 8A-8C. When the bias voltage output module 301 adopts the first implementation manner, as shown in FIG. 8A, the electrostatic discharge/over-electric stress protection module 901 is connected to the output end of the first driving module 403; when the bias voltage output module 301 is When the second implementation is used, as shown in FIG. 8B, the electrostatic discharge/over-electric stress protection module 901 is connected to the output end of the second driving module 504; when the bias voltage output module 301 adopts the third implementation mode. As shown in FIG. 8C, the electrostatic discharge/overvoltage stress protection module 901 is connected to the output of the third drive module 704. Thus, when there is excessive electrical stress or static electricity in the circuit, for example, the voltage of the excessive electrical stress or static electricity is 10 kV, the electrostatic discharge/over-electric stress protection module 901 is at an extremely high speed, for example, 10 ^- The speed of the ¹² S level changes the high impedance of the ESD/Extra-stress protection module 901 to a low impedance while absorbing surge power of up to several kilowatts, so that the voltage across the bias voltage output module 301 is at a safe value. For example, 2.5V or the like, thereby effectively protecting the respective devices in the bias voltage output module 301 from transient high voltage surges.

It should be noted that, since the ESD/EOS event is usually triggered by the peripheral device, the first driving module 403 or the second driving module 504 or the third driving module 704 in the bias voltage output module 301 is directly connected to the earphone, and the earphone The peripheral device, that is, the first driving module 403 or the second driving module 504 or the third driving module 704 is the device that is most easily in contact with the outside, so that when an ESD/EOS event is generated, the first driving module 403 or the second driving module The 504 or the third driving module 704 is the device that is first subjected to a high voltage impact, and therefore, the electrostatic discharge/overelectric stress protection module 901 is connected to the first driving module 403 or the second driving module 504 or the third driving module 704. Thus, it can be avoided that each device in the bias voltage output module 301 is damaged by a transient high voltage.

As an example, the electrostatic discharge/over-electric stress protection module 901 can be composed of two diodes packaged together, as shown in FIG. When the voltage generated by the ESD/EOS event is positive, the upper diode in Figure 9 is divided. When the voltage generated by the ESD/EOS event is negative, the lower diode in Figure 9 is divided. The device in the bias voltage output module 301 is thus protected. Of course, the electrostatic discharge/over-electric stress protection module 305 can also be directly implemented by using an ESD/EOS protector such as a transient voltage suppressor (TVS) diode, and the model and parameters of the ESD/EOS protector should be selected. It is determined according to the layout of each device in the bias voltage output module 301, the board space available in the terminal device, and the electrical characteristics of the bias voltage output module 301.

After introducing various implementations of the bias voltage output module 301, the logic control module 302, the filter capacitor 303, and the bleeder module 304 in the bias voltage output circuit are described in detail.

The logic control module 302 needs to detect the earphone insertion operation and the earphone extraction operation of the terminal device. When detecting that the earphone is inserted into the terminal device, the control bias voltage output module 301 is at the output bias voltage; when the earphone is detected to be pulled out When the terminal device is in operation, the bias voltage output module 302 is controlled to be in an inoperative state, that is, no bias voltage is output. Since the filter capacitor 303 stores a partial power during the bias voltage output module 301 outputting the bias voltage, when the logic control module 302 detects the operation of the earphone to pull out the terminal device, it is also necessary to control the bleeder module 304 to vent. The amount of power stored by the filter capacitor 303 is released, thereby avoiding popping sound.

As an example, the logic control module 302 can include a control chip and a detection module. The detecting module is configured to detect the insertion and extraction operations of the earphone, and then send the detection result to the control chip, and the control chip makes a judgment result, and then sends the control information to the bias voltage output module 301 and the bleeder module 304. Specifically, the detecting module can detect the insertion and extraction operations of the earphone through the earphone socket. The detecting module can be a detecting pin, and the detecting pin is connected to the left channel detecting end in the earphone socket. Connect a resistor to the sense pin. As shown in Figure 10, the sense pin will output a level. When the earphone is inserted, the metal of the earphone plug will touch the detection pin, so that the level of the detection pin changes, from a high level to a low level; and when the earphone is pulled out from the terminal device, the detection pin is detected. The level changes from low level to high level. In this way, the control chip can determine whether the earphone is inserted or removed according to the value of the level of the detection pin. When the control chip determines the insertion operation of the earphone, the control information that the control bias voltage output module 301 is in an operating state and the bleeder and discharge module 304 is controlled to be in an inoperative state is transmitted. For example, the control chip can control the loop of the bias voltage output module 301 to be in an on state and the loop of the control bleeder module 304 to be in an off state. As an example, referring to FIG. 11, a switching device connected to the control chip may be disposed in the loop of the bias voltage output module 301, and the control chip controls the working state of the bias voltage output module 301 by controlling the switching device, for example, When the control chip detects that the earphone is inserted into the terminal device, the switching device connected to the bias voltage output module 301 is controlled to be closed, so that the loop of the bias voltage output module 301 is turned on, and at this time, the bias voltage output module 301 enters the working state. . When the control chip detects that the earphone is pulled out of the terminal device, the switching device connected to the bias voltage output module 301 is controlled to be disconnected, so that the loop of the bias voltage output module 301 is disconnected. At this time, the bias voltage output module 301 enters the non- Working status. In the embodiment of the present application, the venting and discharging module 304 may also be composed of a switching device, as shown in FIG. When the switching device is in the closed state, the bleeder module 304 is in an active state, and when the switching device is in the off state, the bleeder module 304 is in a non-operating state. For example, when the control chip detects that the earphone is inserted into the terminal device, the control chip controls the switching device to be in an off state. At this time, the bleeder module 304 is in an inoperative state, so that the filter capacitor 303 outputs an offset at the bias voltage output module 301. During the voltage process, the power is stored; when the control chip detects that the earphone is pulled out of the terminal device, the control chip controls the switch device to be in a closed state. At this time, the bleeder and discharge module 304 is in an active state, and a conduction loop is formed with the filter capacitor 303. Thereby, the amount of power stored in the filter capacitor 303 is discharged.

It should be noted that, in practical applications, the logic control module 302 may also be an application processor of the terminal device, for example, an open multimedia application platform (OMAP), or a digital signal processor (digital signal). Processing, DSP), for example, TMS320C54xx, TMS320C55xx or DSP32/32C monolithic devices. A person skilled in the art can make a selection according to actual use requirements, and is not limited herein. The specific model and parameters of the filter capacitor 303 need to be selected according to actual use requirements. Moreover, the switching device constituting the bleeder and discharge module 304 and the switching device for controlling the operating state of the bias voltage output module 301 may be N-type metal-oxide-semiconductor transistors or unidirectional switches or other types of switching devices, and are not used herein. limit.

In the embodiment of the present application, in order to further improve the TDD noise in the bias voltage output circuit, when the bias voltage output module 301 uses the second implementation manner or the third implementation manner, the filter resistor 305 may also be disposed in the circuit. 12A-12B, the filter resistor is connected to the second driving module 504 or the fourth driving module 706, and is used to filter out the bias voltage output circuit when the class AB level conversion control module is in the working state. TDD noise. The resistance of the filter resistor 305 needs to be selected according to actual use requirements, and is not limited herein.

Please refer to FIG. 13 , which is a specific example of the bias voltage output circuit in the embodiment of the present application. Among them, S2 is a switching device composed of Power MOS2, and Power MOS constitutes a fourth driving module 706. In the position of the mark S3 in FIG. 13, a switching device may be further provided for controlling the bias voltage output module 301 to output a bias voltage when the S3 switching device is in a closed state, and triggering a bias when the S3 switching device is in an off state. The voltage output module 301 stops outputting the bias voltage.

In the implementation of the present application, the operating state of the bias voltage output module and the bleeder module is controlled by the logic control module, and after the logic control module detects that the external audio output device is disconnected from the audio playback device, the bias voltage output module is controlled. The bias voltage is not output, so that the external audio output device is disconnected from the power source, and the bleeder module is controlled to bleed off the amount of power stored in the filter capacitor, so that the pop-up sound does not appear in the external audio output device, thereby solving the problem. The problem of popping sound. Further, in the circuit, the logic control module is no longer connected to the switch S1, but is respectively connected to the bias voltage output module and the bleeder module, and the state of the bias voltage output module and the bleeder module is passed through the logic control module. The control solves the problem of the blasting sound, and the venting and discharging module is not directly connected with the interface of the external audio output device, so that the static electricity or the external voltage can be avoided by the venting and discharging module directly hit by the MICP, and the external audio output device can be solved in the prior art. The MCP causes ESD and EOS problems with the bias voltage output circuit, ie, both POP, ESD, and EOS issues are resolved.

After solving the POP, ESD and EOS problems of the external audio output device to the bias voltage output circuit of the audio playback device, for the function of the external audio output device itself, the external audio output device can output the audio signal and the audio playback device is required. Various modes of support for external audio output devices. The external audio output device is an example of a headphone, and the earphone can adopt an OMTP standard system, as shown in FIG. 14A, or a CTIA standard system, as shown in FIG. 14B, or a USB Type-C standard system. With the increasing integration of audio playback devices, the adoption of the USB Type-C standard for headsets has gradually become a trend. When the earphone adopts the USB Type-C standard system, for the audio playback device, since the USB Type-C standard supports the forward and reverse insertion working modes, it is required to be connected between the wires of the earphone socket and the microphone and the earphone respectively. Add a set of analog switches to switch, as shown in Figure 15. Since the analog switch itself has a certain impedance, the series connection of the analog switch causes an impedance to be introduced between the earphone ground and the main board ground, so that when the left and right road signals of the earphone are in the process of transmission, a left and right road signal is generated. Crosstalk occurs, as shown in Figure 16, the output signal of the left side of the earphone is a sine wave signal, and the output signal of the right side of the earphone is a DC signal. The sine of the left side of the earphone is due to the impedance introduced between the earphone ground and the ground of the main board. The wave signal is coupled to the right path of the earphone through the impedance, so that the output signal of the right channel of the earphone may become a sine wave signal whose amplitude is smaller than the amplitude of the output signal of the left side of the earphone, affecting the left and right crosstalk performance of the output signal of the earphone.

In view of this, please refer to FIG. 17. The embodiment of the present application provides a driving circuit of an audio output device, including a processing module 1801, a crosstalk canceling module 1802, a digital-to-analog conversion module 1803, and a driving module 1804, where:

The output of the processing module 1801 is connected to the input end of the crosstalk cancellation module 1802 for generating an audio signal, and outputs the audio signal to the crosstalk cancellation module 1802; the output of the crosstalk cancellation module 1802 and the input end of the digital to analog conversion module 1803. a connection for canceling crosstalk between the left channel signal in the audio signal and the right channel signal in the audio signal, and outputting the processed left channel signal and the processed right channel signal to the digital to analog conversion module 1803 The output end of the digital-to-analog conversion module 1803 is connected to the input end of the driving module 1804, and is configured to perform digital-to-analog conversion processing on the processed left-path signal, obtain and output a left-channel analog audio signal, and the right after the processing The road signal is subjected to digital-to-analog conversion processing to obtain and output a right-channel analog audio signal; the output end of the driving module 1804 is connected to the external audio output device for driving the external audio output device to output the left-channel analog audio signal and the right-channel analog signal Audio signal drive.

In the driving circuit shown in FIG. 17, the audio signal transmission path is transferred to the digital-to-analog conversion module 1803 by the processing module 1801, and a crosstalk canceling module 1802 is added to the path, and the left-channel audio is passed through the crosstalk canceling module 1802. The correlation processing between the signal and the right audio signal causes the crosstalk between the left and right audio signals outputted by the external audio output device to be reduced, which can improve the left and right crosstalk performance of the output signal of the external audio output device in the prior art.

In practical applications, the processing module 1801 may specifically be an application processor (AP), for example, OMAP, or may be a DSP, for example, a single-chip device such as TMS320C54xx, TMS320C55xx, or DSP32/32C. A person skilled in the art can make a selection according to actual use requirements, and is not limited herein.

The processing module 1801 can determine that an audio signal needs to be output according to the user's operation on the audio playback device. For example, when the user performs the operation of playing the song A, at this time, the processing module 1801 acquires the audio data corresponding to the song A, for example, the left channel audio data 1 and the right channel audio data 2, and the left channel audio data 1 and the right. The road audio data 2 is sent to the crosstalk cancellation module 1802.

The crosstalk canceling module 1802 may specifically be a Transaural filter, for example, a Schroeder form or an Atal form Transaural filter, or a modified form filter, for example, a Cooper form or a Bauck form Transaural filter, which is not used herein. limit.

Since the computational load of the Transaural filter is large, in order to reduce the amount of calculation, the crosstalk cancellation module 1802 can also be implemented using a plurality of filter constituent circuits. Please refer to FIG. 18, which is an example of the crosstalk cancellation module 1802. The crosstalk cancellation module 1802 is divided into two parts: a first crosstalk canceling device 1901 that eliminates crosstalk in the left channel audio data 1, and a crosstalk second crosstalk canceling device 1902 in the right channel audio data 2. The first crosstalk canceling device 1901 includes three parts: a first boosting device 19011 for enhancing a specific frequency band portion of the left channel audio data 1, a first delay device 19012 for delay processing the left channel audio data 1, and A first computing means 19013 for eliminating crosstalk of the right channel audio data 2 in the left channel audio data 1, the specific band portion of the left channel audio data 1 being the second portion of the left channel signal. Since the first crosstalk canceling means 1901 and the second crosstalk canceling means 1902 are respectively used for processing the left channel audio data 1 and the right channel audio data 2, the processing is the same, and therefore, the structure is also similar, and therefore, the second crosstalk canceling means 1902 The above three parts are also included, namely the second stiffening device 19021, the second delay device 19022, and the second computing device 19023.

The specific frequency band portion of the first reinforcing device 19011 and the second reinforcing device 19021 can be set by a person skilled in the art according to actual use conditions. The first stiffening device 19011 and the second stiffening device 19021 may be a combination of a filter and an amplifier, which may use one or more combinations of a low pass filter, a band pass filter, or a high pass filter; amplification of the amplifier The coefficients need to be selected based on actual use. Thereby, the second portion of the left channel audio data is acquired by the first enhancement device 19011, and the second portion of the right channel audio data is acquired by the second enhancement device 19021.

The first delay means 19012 is for delaying the left channel audio data 1. For example, the sampling signal of the left audio data 1 is delayed by one sampling period to obtain a sampling signal of the sampling period before the current sampling period, or may be delayed by a preset duration to acquire the time corresponding to the preset duration before the current time. The audio data is not limited here. In order to facilitate the operation, the first delay module 19012 further includes an amplifier for amplifying the delayed audio data to obtain delayed left audio data. The amplification factor of the amplifier can be the same as in the first stiffening device 19011. Similarly, since the processing procedure of the second delay device 19022 is the same as that of the first delay device 19012, the second delay device 19022 is configured to perform delay processing on the right channel audio data 2 to obtain delayed right channel audio data. The first delay module 19012 and the second delay device 19022 may further include an amplifier for performing the delayed audio data. Zoom in. The amplification factor of the amplifier may be the same as the amplification factor in the first reinforcement device 19011, or may be different, and is not limited herein.

In order to eliminate crosstalk between the left channel audio data 1 and the right channel audio data 2, the processing of the first computing device 19013 requires the use of the right channel audio data 2, and the processing of the second computing device 19023 requires the use of the left channel audio data 2, The specific calculation method is as follows:

The first computing device 19013 performs a summation operation on the second partial left channel audio data output by the first boosting device 19011, the left channel audio data 1 and the delayed right channel audio data output by the second delay device 19022, thereby eliminating the right The crosstalk of the audio data 2 to the left audio data 1. The second computing device 19923 performs a first operation on the second portion of the right audio data, the right audio data 2, and the delayed left audio data output by the first delay module 19012, which is output by the second boosting device 19021, the first operation It may be a summation operation or a weighted summation operation or the like, thereby eliminating crosstalk of the left channel audio data 1 to the right channel audio data 2.

The digital-to-analog conversion module 1803 may specifically be a digital to analog converter (DAC), for example, a weight resistance network DAC, an R-2R inverted T-resistance network DAC, and a single-value current type network DAC, etc., of course, digital mode The conversion module 1803 may also be a circuit composed of a digital register, an analog electronic switch, a bit-resistance network, a summing operational amplifier, and a reference voltage source, which are not limited in the embodiment of the present application.

After the crosstalk cancellation module 1802 sends the processed left channel audio data 1 and the processed right channel audio data 2 to the digital to analog conversion module 1803, the data conversion module 1803 respectively processes the processed left channel audio data 1 and the right channel. The audio data 2 is converted to an analog audio signal, and the output value drive module 1804.

The drive module 1804 can be specifically configured by an operational amplifier. For example, the left audio signal and the right audio signal respectively correspond to one operational amplifier. When the operational amplifier detects an audio signal input, the analog audio signal is amplified according to a preset amplification gain parameter to drive the external audio playback device. The corresponding analog audio signal is output through the left and right output devices. Please refer to FIG. 19, which is an example of a driving circuit provided by an embodiment of the present application.

Since each audio playback device, such as a mobile phone or a tablet computer, may have different impedance to ground, and when the impedance of the audio playback device is different, the processing module 1801 and the crosstalk cancellation module 1804 may be used for left and right audio. The processing parameters of the signal also change. For example, when the impedance to the ground of the audio playback device is larger, in order to make the quality of the audio signal output by the external audio output device the same, the amplitudes of the left audio data 1 and the right audio data 2 output by the processing module 1801 also need to be increased. Therefore, referring to FIG. 20, the driving circuit further includes:

An impedance detecting module 1805, an input end of the impedance detecting module 1805 is connected to an output end of the driving module 1804, and an output end of the impedance detecting module 1805 is connected to the processing module 1801, for detecting an impedance value of the external audio output device, and the The impedance value is output to the processing module 1801 such that the processing module 1801 adjusts the voltage of the audio signal based on the impedance value.

In an actual application, the impedance detecting module 1805 may specifically measure the current and voltage across the external audio output device, determine the impedance of the external audio output device by the ratio of the voltage to the current, and may also use some impedance detecting device, such as an oscilloscope. , an impedance test board, etc., or an impedance test chip, such as the AD5933, etc., can be selected by those skilled in the art according to actual use requirements.

Further, since the impedance of the ground of each audio playback device is different, the processing parameters of the left and right audio data of the different audio playback devices by the crosstalk cancellation module 1802 are also different. Therefore, in order to enable the crosstalk cancellation module 1802 to be adapted differently The audio playback device may further be provided with a correction module 1806, and the correction module automatically adjusts the processing parameters according to different audio playback devices.

As an example, referring to FIG. 21, the correction module 1806 may include a stereo separation detection module and a comparator. The input ends of the stereo separation detection module respectively input left and right analog audio signals, and are determined by the stereo separation detection module. The stereo separation of the current left and right analog audio signals. The greater the stereo separation, the greater the crosstalk characterizing the left and right analog audio signals. The output of the stereo separation detection module is connected to an input of the comparator, for example The cathode of the comparator, the other input of the comparator, for example, the anode of the comparator is set to a preset stereo separation parameter value, and the output of the comparator is connected to the crosstalk cancellation module 1802. When the stereo separation detection module outputs the stereo separation parameter value of the current left and right analog audio signals to one input of the comparator, the comparator compares the stereo separation parameter value with the preset stereo separation parameter value. , get the comparison result. For example, when the comparison result is +1, it indicates that the stereo separation parameter value is smaller than the preset stereo separation parameter value, indicating that the crosstalk cancellation module 1802 invalidates the parameter for crosstalk cancellation of the audio output device; when the comparison result is -1 When the stereo separation parameter value is greater than the preset stereo separation parameter value, indicating that the crosstalk cancellation module 1802 is valid for the crosstalk cancellation of the audio output device, the parameters in the crosstalk cancellation module 1802 need to be adjusted.

When the comparator obtains the comparison result, the comparison result is output to the crosstalk cancellation module 1802. For example, when the comparison result is +1, the crosstalk cancellation module 1802 can keep the value of the parameter currently used for crosstalk cancellation of the audio output device unchanged; when the comparison result is -1, the crosstalk cancellation module 1802 The value of the parameter currently used for crosstalk cancellation of the audio output device can be increased or decreased, and then the same method is used for multiple adjustments until the comparison result of the comparator output is +1.

In this way, the self-learning process of the crosstalk cancellation module 1802 is implemented by the correction module 1806, so that the adjustment process of the driving circuit is more convenient.

It should be noted that since the stereo separation degree and the crosstalk degree are inversely proportional to each other, the stereo separation degree detection module in the correction module 1806 can also be replaced with the crosstalk detection module, so that the crosstalk detection module can directly determine the crosstalk detection module. The degree of crosstalk between the left and right analog audio signals is then outputted to the comparator for comparison, and finally the comparison result is output to the crosstalk cancellation module 1802 to adjust the left and right signals in the crosstalk cancellation module 1802. The parameters for crosstalk cancellation processing.

Of course, the correction module 1806 can also include an analog to digital converter (ADC) and a digital circuit. The ADC can directly detect the magnitude of the crosstalk of the audio output device, and then convert the order of magnitude to a level signal through the digital circuit. Feedback to the crosstalk cancellation module 1802. The correction module 1806 can also be a manual adjustment module, which is adjusted by the technician according to the crosstalk parameter values of the current left and right analog audio signals, and is not limited herein.

In the above technical solution, the crosstalk cancellation module is added to the path of the processing module and the digital-to-analog conversion module, and the left audio signal and the right audio signal are correlated, so that the output of the external audio output device is finally left, The crosstalk between the right audio signals is reduced, which can improve the left and right crosstalk performance of the output signal of the external audio output device in the prior art.

The above embodiments are only used to describe the technical solutions of the present application in detail, but the description of the above embodiments is only used to help understand the embodiments of the present application and the core ideas thereof, and should not be construed as limiting the present application. Those skilled in the art are susceptible to variations or alternatives within the scope of the present disclosure.

Claims

A bias voltage output circuit for an audio playback device, comprising: a bias voltage output module, a logic control module, a filter capacitor, and a bleeder and discharge module, wherein:

The bias voltage output module is respectively connected to the logic control module and an external audio output device connected to the audio playback device, and is configured to output a bias voltage under the action of the logic control module, the offset a voltage for driving the external audio output device;

The filter capacitors are respectively connected to the ground and the bias voltage output module for filtering noise generated by the bias voltage output module during outputting the bias voltage, and at the bias The voltage output module stores the amount of power during the output of the bias voltage;

The bleeder and discharge modules are respectively connected to the ground, the filter capacitor, and the logic control module, and are configured to bleed the power stored by the filter capacitor under the action of the logic control module;

The logic control module is configured to trigger the bias voltage output module to output the bias voltage when the external audio output device is determined to be connected to the audio playback device, and control the bleeder module to prohibit bleed The amount of power stored by the filter capacitor triggers the bias voltage output module to stop outputting the bias voltage and control the bleeder module when determining that the external audio output device is disconnected from the audio playback device The amount of power stored by the filter capacitor is discharged.
The bias voltage output circuit of claim 1 , wherein the bias voltage output module comprises a voltage generating module, an error amplifying module, a first driving module, and an output voltage sampling and feedback module, wherein:

An output end of the voltage generating module is connected to a first input end of the error amplifying module, the voltage generating module is configured to generate a reference voltage, and output the reference voltage to the error amplifying module;

The output of the error amplifying module is connected to the input end of the first driving module, and the error amplifying module is configured to perform voltage stabilization processing on the reference voltage, and obtain and output the bias to the first driving module. Set voltage

The output end of the first driving module is connected to the external audio output device for driving the external audio output device by the bias voltage;

An output end of the output voltage sampling and feedback module is connected to an output end of the first driving module, and an output end is connected to a second input end of the error amplifying module, and the output voltage sampling and feedback module is used for The bias voltage is sampled, and the sampling result is fed back to the error amplification module;

The error amplifying module is configured to adjust the reference voltage according to the sampling result.
The bias voltage output circuit of claim 1 , wherein the bias voltage output module comprises a voltage generating module, an error amplifying module, a class AB level shift control module, a second driving module, and an output voltage sampling and Feedback module, where:

An output end of the voltage generating module is connected to a first input end of the error amplifying module, the voltage generating module is configured to generate a reference voltage, and output the reference voltage to the error amplifying module;

An output end of the error amplifying module is connected to an input end of the class AB level conversion control module, and the error amplifying module is configured to perform voltage stabilization processing on the reference voltage to obtain and convert to the class AB level The control module outputs the adjusted voltage;

An output end of the class AB level conversion control module is connected to an input end of the second driving module, configured to convert the adjusted voltage into the bias voltage, and output the a bias voltage, the noise of the bias voltage being less than the noise of the adjusted voltage;

The output end of the second driving module is connected to the external audio output device, and is configured to drive the external audio output device by using the class AB control level signal;

An output end of the output voltage sampling and feedback module is connected to an output end of the second driving module, and an output end is connected to a second input end of the error amplifying module, and the output voltage sampling and feedback module is used for The bias voltage is sampled, and the sampling result is fed back to the error amplification module;

The error amplifying module is configured to adjust the reference voltage according to the sampling result.
The bias voltage output circuit of claim 3, wherein the bias voltage output circuit further comprises:

And a first filter resistor connected to the second driving module, configured to filter out time division multiplexed TDD noise generated in the bias voltage output circuit.
The bias voltage output circuit according to claim 1, wherein the bias voltage output module comprises a voltage generating module, an error amplifying module, a bidirectional switch, a third driving module, a class AB level conversion control module, and a A four-drive module and an output voltage sampling and feedback module, wherein:

An output end of the voltage generating module is connected to a first input end of the error amplifying module, the voltage generating module is configured to generate a reference voltage, and output the reference voltage to the error amplifying module;

An output end of the error amplifying module is connected to an input end of the bidirectional switch, a first output end of the bidirectional switch is connected to the third driving module, and a second output end of the bidirectional switch is connected to the AB class The level shift control module is connected, and when the bidirectional switch forms a first path with the first output end of the bidirectional switch, the error amplifying module is configured to perform voltage stabilization processing on the reference voltage to obtain and The third driving module outputs the bias voltage, and when the bidirectional switch forms a second path with the second output end of the bidirectional switch, the error amplifying module is configured to perform voltage stabilization processing on the reference voltage to obtain And outputting the adjusted voltage to the class AB level conversion control module;

The bidirectional switch is connected to the logic control module, and is configured to select to form the first path or form the second path under the action of the logic control module;

The output end of the third driving module is connected to the external audio output device, and is configured to drive the external audio output device by the bias voltage when the bidirectional switch forms the first path;

An output end of the class AB level conversion control module is coupled to an input end of the fourth driving module, and configured to convert the adjusted voltage into the second path when the bidirectional switch forms the second path Offsetting a voltage and outputting the bias voltage to the fourth driving module, the noise of the bias voltage being less than the noise of the adjusted voltage;

The output end of the fourth driving module is connected to the external audio output device, and is configured to drive the external audio output device by the bias voltage when the bidirectional switch forms the second path;

The input ends of the output voltage sampling and feedback module are respectively connected to the output end of the third driving module and the output end of the fourth driving module, and the output end is connected to the second input end of the error amplifying module. The output voltage sampling and feedback module is configured to sample the bias voltage and feed back the sampling result to the error amplification module;

The error amplifying module is configured to adjust the reference voltage according to the sampling result.
The bias voltage output circuit of claim 4, wherein the bias voltage output circuit further comprises:

And a second filter resistor connected to the fourth driving module for filtering time division multiplexed TDD noise generated in the bias voltage output circuit.
The bias voltage output circuit according to any one of claims 2-6, wherein the bias voltage output module further comprises:

An electrostatic discharge/over-electric stress protection module coupled to the input end of the output voltage sampling and feedback module for reducing the bias voltage when excessive electrical stress or static electricity is present in the bias voltage output circuit The output module includes a voltage across at least one of the plurality of modules, the at least one module not including the electrostatic discharge/over-electric stress protection module.
The bias voltage output circuit according to any one of claims 1 to 7, wherein the bleeder and discharge module is an N-type metal-oxide-semiconductor transistor or a unidirectional switch.
The bias voltage output circuit according to claim 3, wherein the second driving module is a P-type metal-oxide-semiconductor transistor or an N-type metal-oxide-semiconductor transistor.
A driving circuit for an audio output device, comprising: a processing module, a crosstalk canceling module, a digital to analog conversion module, and a driving module, wherein:

An output end of the processing module is connected to an input end of the crosstalk cancellation module, and is configured to generate and output an audio signal to the crosstalk cancellation module, where the audio signal includes a left channel signal and a right channel signal;

The crosstalk cancellation module is connected to an input end of the digital-to-analog conversion module for canceling crosstalk between the left channel signal and the right channel signal, and outputting crosstalk cancellation to the digital-to-analog conversion module The left signal after the cancellation and the right signal after the crosstalk is eliminated;

The digital-to-analog conversion module is connected to an input end of the driving module, and is configured to perform digital-to-analog conversion processing on the left-channel signal after the crosstalk cancellation, and obtain and output a left-channel analog audio signal to the driving module. And performing digital-to-analog conversion processing on the cross-talking right-path signal, and obtaining and outputting a right-channel analog audio signal to the driving module;

The driving module is connected to the external audio output device for driving the left output device of the external audio output device to output the left analog audio signal, and driving the right output device of the external audio output device The right analog audio signal is output.
The driving circuit according to claim 10, wherein the crosstalk canceling module comprises a first boosting device, a first delaying device, a first computing device, a second reinforcing device, a second delay device, and a second computing device, among them,

The first reinforcing device is configured to filter out a first portion of the left channel signal that is outside the preset frequency band of the left channel signal, and is located on the preset frequency band of the left channel signal according to a preset amplification factor. The second portion of the left signal is amplified to obtain a first left channel signal, and the first delay device is configured to acquire a left channel signal within a preset number of sampling periods before the current sampling period, where the first computing device uses Performing a first operation on the left signal, the second partial left signal, and the left signal in the preset number of sampling periods before the current sampling period to obtain the processed left signal ;

The second reinforcing device is configured to filter out a first portion of the right channel signal of the right channel signal that is outside the preset frequency band, and according to the preset amplification factor, the right channel signal is located in the a second portion of the right channel signal on the frequency band is amplified to obtain a first right channel signal, and the second delay device is configured to acquire a right channel signal in the preset number of sampling periods before the current sampling period, The second computing device is configured to perform the first operation on the right channel signal, the second partial right channel signal, and the right channel signal in the preset number of sampling periods before the current sampling period, to obtain The processed right channel signal.
The driving circuit according to claim 11, wherein the driving circuit further comprises an impedance detecting module, wherein

An input end of the impedance detecting module is connected to an output end of the driving module, and an output end is connected to the processing module, wherein the impedance detecting module is configured to detect an impedance of the external audio output device, and send the impedance to the processing module Outputting the impedance;

The processing module is further configured to adjust a voltage of the audio signal according to the impedance.
The driving circuit according to claim 11 or 12, wherein the driving circuit further comprises a correction module, wherein

An input end of the correction module is connected to an output end of the driving device, and an output end is connected to the crosstalk canceling module, and the correcting module is configured to detect the left analog audio signal and the right analog audio signal Stereo separation between the two, and outputting the stereo separation to the crosstalk cancellation module;

The crosstalk cancellation module is further configured to adjust a value of the preset amplification factor in the first reinforcement device or the second reinforcement device according to the stereo separation degree, and/or the first delay The preset number of values in the device or the second delay device.