Noise elimination circuit, audio driving chip and noise elimination method

Abstract

The invention belongs to the technical field of computers, and particularly discloses a noise elimination circuit, an audio driving chip and a noise elimination method. The circuit comprises a voltage generation sub-circuit used for generating a preset common-mode voltage and a driving sub-circuit used for generating an audio driving signal, the noise elimination circuit further comprises a first analog switch and a second analog switch which are controlled according to the control signal. Under the condition that the driving sub-circuit does not output the audio driving signal, the control signal controls the first analog switch to be switched on and controls the second analog switch to be switched off, so that the preset common-mode voltage is transmitted to the output end of the audio driving signal through the first analog switch; and under the condition that the driving sub-circuit outputs the audio driving signal, the control signal controls the second analog switch to be switched on and controls the first analog switch to be switched off, so that the audio driving signal is transmitted to the output end of the audio driving signal through the second analog switch. The circuit eliminates POP noise by generating the preset common-mode voltage, and is easy to control and integrate.

Description

Technical Field

[0001] The present disclosure relates to the field of computer technology, and in particular to a noise elimination circuit, an audio driver chip, and a noise elimination method. Background Art

[0002] In audio applications, the audio drive signal output by the audio driver chip will be output to loads such as headphone devices through DC blocking capacitors. In the process of the audio drive signal rising from 0V to the expected common-mode voltage of the output signal, the voltage mutation will be coupled to the load input through the DC blocking capacitor, causing noise to be generated in loads such as headphones or speakers. This noise is called POP noise.

[0003] In the related art, additional external circuits are usually connected to the outside of the chip, such as using a larger external capacitor to slow down the change speed of the voltage of the audio drive signal when it rises and falls, thereby avoiding the DC isolation capacitor coupling unexpected voltage mutations to the external load.

[0004] However, such solutions require additional external circuit design, are difficult to control and integrate, and are costly.

[0005] Public Content

[0006] To this end, the present disclosure provides a noise elimination circuit audio driver chip and a noise elimination method to solve the problems in the prior art of high cost, complex implementation and difficult integration of POP noise elimination caused by connecting additional external circuits outside the chip.

[0007] In order to achieve the above-mentioned object, the first aspect of the present disclosure provides a noise elimination circuit, which is applied to an audio driver chip, and the noise elimination circuit comprises: a voltage generation subcircuit for generating a preset common-mode voltage and a driver subcircuit for generating an audio drive signal, wherein a preset voltage value of the preset common-mode voltage is determined according to a signal voltage value of a signal common-mode voltage of the audio drive signal;

[0008] The noise elimination circuit further includes: a first analog switch and a second analog switch controlled according to a control signal, the first analog switch being arranged between the voltage generating subcircuit and the output terminal of the audio driving signal, and the second analog switch being arranged between the driving subcircuit and the output terminal of the audio driving signal;

[0009] Wherein, when the driving subcircuit does not output the audio driving signal, the control signal controls the first analog switch to be turned on and the second analog switch to be turned off, so that the preset common mode voltage output by the voltage generating subcircuit is transmitted to the output end of the audio driving signal through the first analog switch;

[0010] When the driving sub-circuit outputs an audio driving signal, the control signal controls the second analog switch to be turned on and controls the first analog switch to be turned off, so that the audio driving signal output by the driving sub-circuit is transmitted to the output end of the audio driving signal through the second analog switch.

[0011] In some examples, the voltage generating subcircuit and the driving subcircuit are connected to the same power supply terminal, and the voltage generating subcircuit includes a first voltage dividing resistor and a second voltage dividing resistor; a first resistance value of the first voltage dividing resistor is the same as a second resistance value of the second voltage dividing resistor;

[0012] Wherein, the first end of the first voltage-dividing resistor is connected to the power supply end, and the second end of the first voltage-dividing resistor is connected to the second end of the second voltage-dividing resistor and the first analog switch;

[0013] A first end of the second voltage-dividing resistor is connected to the ground end, and a second end of the second voltage-dividing resistor is connected to the second end of the first voltage-dividing resistor and the first analog switch;

[0014] The voltage outputted by the second end of the first voltage-dividing resistor and the second end of the second voltage-dividing resistor is the preset common-mode voltage.

[0015] In some examples, the voltage generating subcircuit further includes an operational amplifier, and the second end of the first voltage-dividing resistor and the second end of the second voltage-dividing resistor are connected to the first analog switch through the operational amplifier;

[0016] The second end of the first voltage-dividing resistor and the second end of the second voltage-dividing resistor are respectively connected to the in-phase input terminal of the operational amplifier, so as to input the preset common-mode voltage to the operational amplifier;

[0017] The output end of the operational amplifier is connected to the inverting input end of the operational amplifier and the first analog switch respectively, and is used to drive and output the preset common mode voltage.

[0018] In some examples, the voltage generation subcircuit further includes a filter capacitor, a first end of the filter capacitor is connected to a ground terminal, and a second end of the filter capacitor is connected to an output terminal of the operational amplifier and the first analog switch;

[0019] During the generation of the preset common-mode voltage, the filter capacitor is used to adjust the voltage change speed of the preset common-mode voltage output by the operational amplifier.

[0020] In some examples, the first analog switch is a first transistor, the second analog switch is a second transistor, and when the conduction conditions of the first transistor and the second transistor are opposite, the number of the control signal is one;

[0021] When the control signal controls the first transistor to be turned on, the control signal controls the second transistor to be turned off;

[0022] When the control signal controls the second transistor to be turned on, the control signal controls the first transistor to be turned off.

[0023] In some examples, the first analog switch is a third transistor, the second analog switch is a fourth transistor, and when the conduction conditions of the third transistor and the fourth transistor are the same, the control signal includes a first control signal and a second control signal with opposite values;

[0024] When the first control signal controls the third transistor to be turned on, the second control signal controls the fourth transistor to be turned off;

[0025] When the second control signal controls the fourth transistor to be turned on, the first control signal controls the third transistor to be turned off.

[0026] A second aspect of the present disclosure provides an audio driver chip, wherein the audio driver chip includes the above-mentioned noise elimination circuit.

[0027] A third aspect of the present disclosure provides a noise elimination method, which is applied to the above-mentioned audio driver chip, and comprises:

[0028] When the driving subcircuit of the audio driving chip does not output the audio driving signal, a control signal is generated to control the first analog switch to be turned on and the second analog switch to be turned off, so that the preset common mode voltage output by the voltage generating subcircuit is transmitted to the output end of the audio driving signal through the first analog switch;

[0029] When the driving sub-circuit outputs the audio driving signal, a control signal is generated to control the second analog switch to be turned on and the first analog switch to be turned off, so that the audio driving signal output by the driving sub-circuit is transmitted to the output end of the audio driving signal through the second analog switch.

[0030] In some examples, the first analog switch is a first transistor, the second analog switch is a second transistor, the conduction conditions of the first transistor and the second transistor are opposite, and the number of the control signal is one;

[0031] When the driving subcircuit of the audio driving chip does not output the audio driving signal, setting the level state of the control signal to a preset value, controlling the first analog switch to be turned on and the second analog switch to be turned off;

[0032] When the driving sub-circuit outputs the audio driving signal, the level state of the control signal is switched to control the second analog switch to be turned on and the first analog switch to be turned off.

[0033] In some examples, the first analog switch is a third transistor, the second analog switch is a fourth transistor, the third transistor and the fourth transistor have the same conduction condition, and the control signal includes a first control signal and a second control signal having opposite values;

[0034] When the driving subcircuit of the audio driving chip does not output an audio driving signal, the level state of the first control signal is set to a first preset value to control the first analog switch to be turned on, and the level state of the second control signal is set to a second preset value to control the second analog switch to be turned off;

[0035] When the driving sub-circuit outputs the audio driving signal, the level states of the first control signal and the second control signal are switched respectively to control the first analog switch to be disconnected and the second analog switch to be turned on.

[0036] The present disclosure has the following advantages:

[0037] In an embodiment of the present disclosure, the noise elimination circuit includes a voltage generation subcircuit for generating a preset common mode voltage and a driving subcircuit for generating an audio driving signal, wherein the preset voltage value of the preset common mode voltage is determined according to the signal voltage value of the signal common mode voltage of the audio driving signal; the noise elimination circuit also includes: a first analog switch and a second analog switch controlled by a control signal, the first analog switch is arranged between the voltage generation subcircuit and the output end of the audio driving signal, and the second analog switch is arranged between the driving subcircuit and the output end of the audio driving signal. Thus, when the driving subcircuit does not output the audio driving signal, the control signal is used to control the first analog switch to be turned on and the second analog switch to be turned off, so that the preset common mode voltage output by the voltage generation subcircuit is transmitted to the output end of the audio driving signal through the first analog switch, and the expected common mode voltage is generated in advance; and when the driving subcircuit outputs the audio driving signal, the control signal controls the second analog switch to be turned on and the first analog switch to be turned off, so that the audio driving signal output by the driving subcircuit is transmitted to the output end of the audio driving signal through the second analog switch.

[0038] It can be seen that even when there is no audio drive signal output, the embodiment of the present disclosure can generate a preset common mode voltage in advance through the voltage generation subcircuit, thereby avoiding the voltage mutation phenomenon generated when the audio drive signal is output. In addition, the noise elimination circuit of the embodiment of the present disclosure is arranged inside the audio drive chip, and there is no need to connect an additional circuit outside the chip. The circuit area is small, the power consumption is low, and the consumption cost is low. Moreover, the control of the analog switch can be realized only through the control signal, and the control method is simple, easy to control and integrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are used to provide further understanding of the present disclosure and constitute a part of the specification. They are used to explain the present disclosure together with the following detailed description, but do not constitute a limitation of the present disclosure.

[0040] Figure 1 A schematic diagram of a noise elimination circuit provided by an embodiment of the present disclosure;

[0041] Figure 2 A schematic diagram of a noise elimination circuit provided by an embodiment of the present disclosure;

[0042] Figure 3 A schematic diagram of a noise elimination circuit provided by an embodiment of the present disclosure;

[0043] Figure 4 A schematic diagram of a noise elimination circuit provided by an embodiment of the present disclosure;

[0044] Figure 5 A schematic diagram of a noise elimination circuit provided by an embodiment of the present disclosure;

[0045] Figure 6 A schematic diagram of an audio driver chip provided in an embodiment of the present disclosure;

[0046] Figure 7 A flowchart of a noise elimination method provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0047] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0048] As used in this disclosure, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0049] The terms used in the present disclosure are only used to describe specific embodiments and are not intended to limit the present disclosure.As used in the present disclosure, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0050] When the terms “comprising” and / or “made of…” are used in the present disclosure, it specifies the existence of the stated features, integers, steps, operations, elements and / or components, but does not exclude the existence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0051] The embodiments described in the present disclosure may be described with reference to plan views and / or cross-sectional views by way of ideal schematic diagrams of the present disclosure. Therefore, the exemplary illustrations may be modified according to manufacturing techniques and / or tolerances.

[0052] Unless otherwise defined, all terms (including technical and scientific terms) used in this disclosure have the same meaning as those commonly understood by those of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning unless explicitly defined in this disclosure.

[0053] In audio application scenarios, the audio driving signal output by the audio driver chip will be transmitted to headphones, speakers and other devices through DC blocking capacitors.

[0054] POP Noise is also known as P sound or POP noise. It refers to the voltage mutation when the audio driving signal output by the audio driver chip rises from 0V to the expected common-mode voltage. It is coupled to the external audio load such as the headphone device through the DC blocking capacitor, resulting in noise generated by the load.

[0055] In the related art, in order to eliminate POP noise, additional external circuits are often added outside the audio driver chip, for example, by adding a larger external capacitor to prevent the DC isolation capacitor from coupling unexpected voltage mutations to external loads such as headphone devices. However, the above solution requires additional external circuit design and external devices require additional switch control, which is not only difficult to integrate and control, but also requires high costs.

[0056] In order to solve the above problems, the embodiments of the present disclosure provide a noise elimination circuit, an audio driver chip and a noise elimination method. The noise elimination circuit is arranged inside the audio driver chip, and there is no need to connect an additional circuit outside the chip. The circuit has the advantages of simple structure, small area and low power consumption. Moreover, the control of the analog switch can be achieved through a simple control signal. The control method is simple and easy to control and integrate.

[0057] In a first aspect, an embodiment of the present disclosure provides a noise elimination circuit, which is applied to an audio driver chip.

[0058] Figure 1 A schematic diagram of a noise elimination circuit provided by an embodiment of the present disclosure is shown in FIG. Figure 1 The noise elimination circuit 100 includes: a voltage generating sub-circuit 101 , a driving sub-circuit 102 , a first analog switch 103 and a second analog switch 104 .

[0059] The voltage generating subcircuit 101 is used to generate a preset common mode voltage. The driving subcircuit 102 is used to generate an audio driving signal.

[0060] Specifically, when the driving sub-circuit 102 generates an audio driving signal, the audio driving signal may generate a signal common mode voltage capable of driving an external load such as an earphone device.

[0061] It should be noted that in order to avoid voltage mutation caused by generating an audio driving signal, the preset voltage value of the preset common mode voltage generated by the voltage generating subcircuit 101 needs to be determined according to the signal voltage value of the signal common mode voltage of the audio driving signal.

[0062] Specifically, the preset voltage value of the preset common mode voltage may be the same as the signal voltage value of the signal common mode voltage.

[0063] Furthermore, in actual applications, affected by external factors such as the stability of the power supply end or the circuit stability, the preset voltage value of the preset common-mode voltage may also deviate from the signal voltage value of the signal common-mode voltage, wherein the voltage difference between the preset voltage value of the preset common-mode voltage and the signal voltage value of the signal common-mode voltage needs to be less than the preset deviation threshold.

[0064] The first analog switch 103 is arranged between the voltage generating sub-circuit 101 and the output terminal Out of the audio driving signal.

[0065] The output terminal Out of the audio driving signal is a port for the audio driving chip to output the audio driving signal to an external load such as headphones.

[0066] Typically, a DC blocking capacitor is provided between the output terminal Out of the audio driving signal and an external load such as headphones, so that the audio driving signal outputted from the output terminal Out of the audio driving signal is transmitted to the external load such as headphones through the DC blocking capacitor.

[0067] It should be noted that the first analog switch 103 is disposed between the voltage generating subcircuit 101 and the output terminal Out of the audio driving signal, specifically, the first analog switch 103 is electrically connected to the voltage generating subcircuit 101 and the output terminal Out of the audio driving signal respectively.

[0068] Thus, when the first analog switch 103 is turned on, the voltage generating subcircuit 101 is connected to the output terminal Out of the audio driving signal, and when the first analog switch 103 is turned off, the voltage generating subcircuit 101 is disconnected from the output terminal Out of the audio driving signal.

[0069] The second analog switch 104 is disposed between the driving sub-circuit 102 and the output terminal Out of the audio driving signal. That is, the second analog switch 104 is electrically connected to the driving sub-circuit 102 and the output terminal Out of the audio driving signal respectively.

[0070] Therefore, when the second analog switch 104 is turned on, the driving sub-circuit 102 is connected to the output terminal Out of the audio driving signal, and when the second analog switch 104 is turned off, the driving sub-circuit 102 is disconnected from the output terminal Out of the audio driving signal.

[0071] The first analog switch 103 and the second analog switch 104 may be transistors used as switching devices, such as Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), which is not limited in the embodiments of the present disclosure.

[0072] It should also be noted that when the first analog switch 103 and the second analog switch 104 are transistors used as switching devices, the corresponding transistor conduction conditions may be the same or different.

[0073] For example, the first analog switch 103 and the second analog switch 104 can both be N-type metal-oxide-semiconductor (NMOS) transistors or P-channel metal oxide semiconductor (PMOS) transistors. In this case, the first analog switch 103 and the second analog switch 104 have the same conduction conditions, such as when the gate of the first analog switch 103 and the gate of the second analog switch 104 input a low level, the first analog switch 103 and the second analog switch 104 are turned on.

[0074] For another example, the first analog switch 103 and the second analog switch 104 are NMOS type transistors and PMOS type transistors, respectively, or the first analog switch 103 and the second analog switch 104 are PMOS type transistors and NMOS type transistors, respectively. In this case, the conduction conditions of the first analog switch 103 and the second analog switch 104 are opposite, such as when the gate of the first analog switch 103 is input with a low level and the gate of the second analog switch 104 is input with a high level, the first analog switch 103 and the second analog switch 104 are turned on.

[0075] The on and off states of the first analog switch 103 and the second analog switch 104 are both controlled by control signals.

[0076] Exemplarily, in the case where the first analog switch 103 and the second analog switch 104 are MOSFETs (MOS tubes for short), if the first analog switch 103 is a PMOS type transistor, the first analog switch 103 is electrically connected to the voltage generating subcircuit 101 and the output terminal Out of the audio driving signal, respectively. Specifically, the source of the first analog switch 103 is electrically connected to the voltage generating subcircuit 101, and the drain of the first analog switch 103 is electrically connected to the output terminal Out of the audio driving signal.

[0077] Among them, the control signal is used to input the gate of the first analog switch 103, and the level state of the control signal is changed to control the on / off state between the source of the first analog switch 103 and the drain of the first analog switch 103, thereby controlling the circuit connection state between the voltage generating subcircuit 101 and the output terminal Out of the audio driving signal.

[0078] Similarly, if the second analog switch 104 is a PMOS type transistor, the second analog switch 104 is electrically connected to the driving sub-circuit 102 and the output end Out of the audio driving signal respectively, which means that: the source of the second analog switch 104 is electrically connected to the driving sub-circuit 102, and the drain of the second analog switch 104 is electrically connected to the output end Out of the audio driving signal.

[0079] The control signal is used to input the gate of the second analog switch 104. By changing the level state of the control signal, the on / off state between the source of the second analog switch 104 and the drain of the second analog switch 104 can be controlled, thereby controlling the circuit connection state between the driving sub-circuit 102 and the output terminal Out of the audio driving signal.

[0080] It should be noted that the control signal may be stored in a storage device such as a register of the audio driver chip, and the level state of the control signal needs to be switched according to whether the driver sub-circuit 102 outputs an audio drive signal.

[0081] Exemplarily, when the driving sub-circuit 102 has not yet output the audio driving signal, the level state of the control signal is a low level, and when the driving sub-circuit 102 outputs the audio driving signal, the level state of the control signal is switched to a high level.

[0082] It should also be noted that the first analog switch 103 and the second analog switch 104 can be controlled by the same control signal, or by different control signals, and the embodiment of the present disclosure does not limit this.

[0083] Exemplarily, when the conduction conditions of the first analog switch 103 and the second analog switch 104 are the same, in order to ensure that the first analog switch 103 and the second analog switch 104 are not turned on at the same time, two control signals can be used for control, such as using a first control signal to control the first analog switch 103 and using a second control signal to control the second analog switch 104. At this time, the level states of the first control signal and the second control signal are opposite.

[0084] When the conduction conditions of the first analog switch 103 and the second analog switch 104 are opposite, only one control signal is needed to control the first analog switch 103 and the second analog switch 104 at the same time.

[0085] In an optional implementation, in order to avoid voltage instability caused by rapid connection or disconnection of the first analog switch 103 and the second analog switch 104, a capacitor can be set between a storage device of the control signal, such as a register, and the first analog switch 103 and the second analog switch 104, so that when the storage device outputs the control signal, the capacitor slows down the level change speed of the control signal, thereby slowing down the connection or disconnection speed of the first analog switch 103 and the second analog switch 104.

[0086] In which, when the driving subcircuit 102 does not output the audio driving signal, the control signal controls the first analog switch 103 to be turned on and controls the second analog switch 104 to be turned off, so that the preset common-mode voltage output by the voltage generating subcircuit 101 is transmitted to the output terminal Out of the audio driving signal through the first analog switch 103.

[0087] When the driving subcircuit 102 outputs an audio driving signal, the control signal controls the second analog switch 104 to be turned on and the first analog switch 103 to be turned off, so that the audio driving signal output by the driving subcircuit 102 is transmitted to the output terminal Out of the audio driving signal through the second analog switch 104 .

[0088] It should be noted that in the embodiment of the present disclosure, when the driving sub-circuit 102 does not output the audio driving signal, the preset common-mode voltage generated by the voltage generating sub-circuit 101 will be transmitted to the output terminal Out of the audio driving signal through the first analog switch 103 under the control of the control signal, so that the output terminal Out of the audio driving signal can transmit the preset common-mode voltage to the DC blocking capacitor, so that the common-mode voltage received by the DC blocking capacitor is the preset common-mode voltage, rather than 0V.

[0089] Correspondingly, when the driving sub-circuit 102 outputs an audio driving signal, under the control of the control signal, the first analog switch 103 is disconnected and the second analog switch 104 is closed, and the audio driving signal generated by the driving sub-circuit 102 is transmitted to the output terminal Out of the audio driving signal through the second analog switch 104, so that the output terminal Out of the audio driving signal transmits the audio driving signal to the DC blocking capacitor, so that the common mode voltage received by the DC blocking capacitor is the signal common mode voltage of the audio driving signal.

[0090] Since the preset voltage value of the preset common-mode voltage is determined according to the signal voltage value of the signal common-mode voltage of the audio driving signal, no matter whether the driving sub-circuit 102 outputs the audio driving signal, no voltage mutation phenomenon will occur on the DC blocking capacitor side, so that when the audio driving signal is transmitted to the load such as headphones through the DC blocking capacitor, no POP noise will occur.

[0091] It can be seen that in the embodiment of the present disclosure, the POP noise is not eliminated by the traditional method, that is, by slowing down the voltage change speed of the audio driving signal, but by setting a voltage generation subcircuit to drive the output of a preset common-mode voltage in advance, so that when the audio driving signal is output, there will be no unexpected voltage mutation phenomenon in the signal coupled by the DC blocking capacitor, thereby avoiding the POP noise generated when the audio driving signal is output.

[0092] As can be seen from the above, even when there is no audio drive signal output, the embodiment of the present disclosure can preset the common mode voltage in advance through the voltage generation subcircuit, thereby avoiding the voltage mutation phenomenon generated when the audio drive signal is output. In addition, the noise elimination circuit of the embodiment of the present disclosure is arranged inside the audio drive chip, and there is no need to connect an additional circuit outside the chip, which not only has a low consumption cost, but also its control of the analog switch can be achieved only through the control signal, reducing the difficulty of control and integration.

[0093] In an optional implementation, in order to enable the voltage generating subcircuit 101 to generate an accurate preset common mode voltage, a voltage dividing resistor may be provided in the voltage generating subcircuit, so that the corresponding preset common mode voltage is outputted through the voltage dividing resistor.

[0094] Figure 2 A circuit structure schematic diagram of a noise elimination circuit provided by an embodiment of the present disclosure is shown.

[0095] Reference Figure 2 In the noise elimination circuit 100 , the voltage generating subcircuit 101 specifically includes a first voltage dividing resistor 1011 and a second voltage dividing resistor 1012 .

[0096] In order to make the preset voltage value of the preset common mode voltage generated by the voltage generating subcircuit 101 the same as the signal voltage value of the signal common mode voltage of the audio driving signal generated by the driving subcircuit 102, the voltage generating subcircuit 101 and the driving subcircuit 102 need to be connected to the same power supply terminal. Thus, the power supply voltage Vin generated by the power supply terminal can be simultaneously input to the voltage generating subcircuit 101 and the driving subcircuit 102, so that the voltage generating subcircuit 101 and the driving subcircuit 102 generate the preset common mode voltage and the audio driving signal.

[0097] Furthermore, in the embodiment of the present disclosure, the resistance value of the first voltage-dividing resistor 1011 and the resistance value of the second voltage-dividing resistor 1012 must be the same.

[0098] The first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012 are circuit elements for reducing the input power supply voltage Vin of the power supply end to a required preset common-mode voltage.

[0099] Specifically, in the embodiment of the present disclosure, the first end of the first voltage-dividing resistor 1011 is connected to the power supply end to receive the power supply voltage Vin generated by the power supply end, and the second end of the first voltage-dividing resistor 1011 is connected to the second end of the second voltage-dividing resistor 1012 and the first analog switch 103.

[0100] A first end of the second voltage-dividing resistor 1012 is connected to the ground end, and a second end of the second voltage-dividing resistor 1012 is connected to a second end of the first voltage-dividing resistor 1011 and the first analog switch 103 .

[0101] In practical applications, the signal voltage value of the signal common mode voltage of the audio driving signal is half of the power supply voltage Vin of the power supply end. Therefore, by connecting the first end of the first voltage-dividing resistor 1011 to the power supply end and the first end of the second voltage-dividing resistor 1012 to the ground end, the total voltage value of the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012 is the power supply voltage value of the power supply end.

[0102] By setting the resistance value of the first voltage-dividing resistor 1011 and the resistance value of the second voltage-dividing resistor 1012 to the same resistance value, the voltage outputted from the second end of the first voltage-dividing resistor 1011 and the second end of the second voltage-dividing resistor 1012 is half of the power supply voltage Vin of the power supply end, that is, a preset common-mode voltage having the same preset voltage value as the signal voltage value of the signal common-mode voltage.

[0103] It should be noted that the embodiment of the present disclosure does not limit the number of resistors included in the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012. That is, the number of resistors included in the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012 can be one or more.

[0104] When the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012 are both composed of multiple resistors, it is only necessary to ensure that the corresponding resistance values ​​of the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012 are the same. The embodiment of the present disclosure does not limit the specific connection form between the multiple resistors included in the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012.

[0105] It should also be noted that when the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012 are both composed of multiple resistors, the first end and the second end of the first voltage-dividing resistor 1011 and the first end and the second end of the second voltage-dividing resistor 1012 refer to the two head and tail connecting ends corresponding to the resistors at both ends of the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012, so that one of the two head and tail connecting ends is arbitrarily selected as the first end, and the other connection end is used as the second end.

[0106] Exemplarily, when the corresponding resistance values ​​of the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012 are both 5Ω, the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012 can both be composed of a 2Ω resistor and a 3Ω resistor connected in series. At this time, for the first voltage-dividing resistor 1011, the head connection end corresponding to the 2Ω resistor can be used as the first end to be connected to the power supply end, and the tail connection end corresponding to the 3Ω resistor can be used as the second end to be connected to the second end of the second voltage-dividing resistor 1012.

[0107] For the second voltage-dividing resistor 1012 , the first connection end corresponding to the 3Ω resistor can be connected to the ground end as the first end, and the tail connection end corresponding to the 2Ω resistor can be connected to the second end of the first voltage-dividing resistor 1011 as the second end.

[0108] Therefore, after the voltage generating subcircuit 101 generates the preset common mode voltage, the preset common mode voltage can be output to the first analog switch 103 , and after the first analog switch 103 is turned on, the preset common mode voltage can be transmitted to the output terminal Out of the audio driving signal.

[0109] Furthermore, in an optional implementation, the inventors found that the driving capability of the preset common-mode voltage output only through the first voltage-dividing resistor 1011 and the second voltage-dividing resistor 1012 is poor. Therefore, in order to improve the driving capability of the output preset common-mode voltage, the operational amplifier can be used as a unit gain buffer, so as to drive the output preset common-mode voltage through the operational amplifier.

[0110] Figure 3 A circuit structure schematic diagram of a noise elimination circuit provided by an embodiment of the present disclosure is shown.

[0111] See also Figure 3 In the noise elimination circuit 100 , the voltage generating sub-circuit 101 thereof further includes an operational amplifier 1013 .

[0112] The second end of the first voltage-dividing resistor 1011 and the second end of the second voltage-dividing resistor 1012 are connected to the first analog switch 103 through the operational amplifier 1013 .

[0113] Specifically, the second end of the first voltage-dividing resistor 1011 and the second end of the second voltage-dividing resistor 1012 are respectively connected to the non-inverting input end of the operational amplifier 1013, so that the preset common-mode voltage outputted from the second end of the first voltage-dividing resistor 1011 and the second end of the second voltage-dividing resistor 1012 can be inputted into the operational amplifier 1013. The output end of the operational amplifier 1013 is respectively connected to the inverting input end of the operational amplifier and the first analog switch 103.

[0114] By connecting the output terminal of the operational amplifier 1013 to the inverting input terminal of the operational amplifier, the operational amplifier 1013 will not perform any amplification or attenuation operation on the input preset common-mode voltage, so that the operational amplifier 1013 maintains its output voltage the same as the input voltage and can provide a low-noise, high-impedance buffer to achieve a stable drive output for the preset common-mode voltage.

[0115] In the noise elimination circuit provided in the embodiment of the present disclosure, an operational amplifier that can work normally after power-on is set in its voltage subcircuit to stably output the preset common-mode voltage, and the first analog switch and the second analog switch are used to realize the switching of the preset common-mode voltage output and the audio drive signal output, thereby realizing POP noise elimination, which is not only simple in control mode, but also easy to control and integrate. The noise elimination circuit has the advantages of simple structure, small area and low power consumption.

[0116] Furthermore, in an optional implementation, the inventors found that the power supply end may generate noise when outputting the power supply voltage, thereby causing voltage changes. Therefore, in order to improve the voltage stability of the preset common-mode voltage generated by the voltage generating subcircuit 101, a filter capacitor can be set in the voltage generating subcircuit 101, thereby adjusting the voltage change speed of the preset common-mode voltage through the filter capacitor.

[0117] Figure 4 A circuit structure schematic diagram of a noise elimination circuit provided by an embodiment of the present disclosure is shown.

[0118] See also Figure 4 In the noise elimination circuit 100 , its voltage generating subcircuit 101 further includes a filtering capacitor 1014 .

[0119] Among them, the first end of the filter capacitor 1014 is connected to the ground end, and the second end of the filter capacitor 1014 is connected to the output end of the operational amplifier 1013 and the first analog switch 103, which is used to adjust the voltage change speed of the preset common mode voltage output by the operational amplifier 1013.

[0120] Specifically, when a preset common-mode voltage is output at the output end of the operational amplifier 1013, when the preset common-mode voltage is higher than the capacitor voltage of the filter capacitor 1014, the filter capacitor 1014 is charged; when the preset common-mode voltage is lower than the capacitor voltage of the filter capacitor 1014, the filter capacitor 1014 is discharged.

[0121] Thus, in this way, the filter capacitor 1014 can smooth the fluctuation amplitude of the preset common-mode voltage, thereby ensuring the voltage change stability of the preset common-mode voltage, and slowing down the voltage change speed caused by the power supply voltage noise during the power-on stage. In addition, since the second end of the filter capacitor 1014 is connected to the first analog switch 103, the preset common-mode voltage smoothed by the filter capacitor 1014 can be effectively output to the first analog switch 103, and transmitted to the output end Out of the audio drive signal via the first analog switch 103.

[0122] In an optional implementation, in order to effectively control the on / off states of the first analog switch 103 and the second analog switch 104 , the number of control signals and the control method may be determined according to the on conditions of the first analog switch 103 and the second analog switch 104 .

[0123] Figure 5 A circuit structure schematic diagram of a noise elimination circuit provided by an embodiment of the present disclosure is shown.

[0124] See also Figure 5 In the noise elimination circuit 100, the first analog switch 103 and the second analog switch 104 are both transistors used as switching devices.

[0125] Specifically, the first analog switch 103 is a first transistor, the second analog switch 104 is a second transistor, and when the conduction conditions of the first transistor and the second transistor are opposite, the number of control signals is one.

[0126] Thus, when the control signal controls the first transistor to be turned on, the control signal can simultaneously control the second transistor to be turned off; and when the control signal controls the second transistor to be turned on, the control signal simultaneously controls the first transistor to be turned off.

[0127] The first transistor and the second transistor are both transistors that can be used as switching devices, such as MOS transistors, and the conduction conditions of the first transistor and the second transistor are opposite. Therefore, the conduction states of the first transistor and the second transistor can be opposite by only one control signal.

[0128] Exemplarily, when the first transistor is an NMOS transistor and the second transistor is a PMOS transistor, the control signal is used to simultaneously input the gates G of the first transistor and the second transistor. The drain D of the first transistor is electrically connected to the voltage generation subcircuit 101, and the source S of the first transistor is electrically connected to the output terminal Out of the audio drive signal. The source S of the second transistor is electrically connected to the driving subcircuit 102, and the drain D of the second transistor is electrically connected to the output terminal Out of the audio drive signal.

[0129] Thus, when the driving sub-circuit 102 does not output the audio driving signal, the level state of the control signal is a high level state, and by simultaneously inputting the control signal in the high level state into the gate G of the first transistor and the second transistor, the first transistor is turned on and the second transistor is turned off. At this time, the preset common-mode voltage generated by the voltage generating sub-circuit 101 can be output to the output terminal Out of the audio driving signal via the first transistor, so that the output terminal Out of the audio driving signal further outputs the preset common-mode voltage to the DC blocking capacitor connected thereto, thereby enabling the preset common-mode voltage output to be generated even when the audio driving signal is not generated.

[0130] When the driving sub-circuit 102 outputs the audio driving signal, the level state of the control signal is switched from a high level state to a low level state, thereby simultaneously inputting the control signal in the low level state into the gate G of the first transistor and the second transistor, so that the first transistor is turned off and the second transistor is turned on. At this time, since the first transistor is turned off, the preset common-mode voltage generated by the voltage generating sub-circuit 101 will not be output to the output terminal Out of the audio driving signal via the first transistor. Since the second transistor is turned on, the audio driving signal generated by the driving sub-circuit 102 can be transmitted to the output terminal Out of the audio driving signal via the second transistor, and the audio driving signal is further output to the DC blocking capacitor connected thereto through the output terminal Out of the audio driving signal, and the external load such as headphones connected thereto is driven through the DC blocking capacitor.

[0131] Exemplarily, when the first transistor is a PMOS transistor and the second transistor is an NMOS transistor, the process of controlling the first transistor and the second transistor to be turned on and off by the control signal is as follows.

[0132] When the driving subcircuit 102 does not output the audio driving signal, the level state of the control signal is a low level state, and the control signal in the low level state is simultaneously input into the gate G of the first transistor and the second transistor, so that the first transistor is turned on and the second transistor is turned off. At this time, the preset common mode voltage generated by the voltage generating subcircuit 101 can be output to the output terminal Out of the audio driving signal via the first transistor, so that the output terminal Out of the audio driving signal further outputs the preset common mode voltage to the DC blocking capacitor connected thereto.

[0133] When the driving subcircuit 102 outputs the audio driving signal, the level state of the control signal is switched from the low level state to the high level state, so that the first transistor is turned off and the second transistor is turned on by simultaneously inputting the control signal in the high level state into the gate G of the first transistor and the second transistor. At this time, since the first transistor is turned off, the preset common mode voltage generated by the voltage generating subcircuit 101 will not be output to the output terminal Out of the audio driving signal through the first transistor, and since the second transistor is turned on, the audio driving signal generated by the driving subcircuit 102 can be transmitted to the output terminal Out of the audio driving signal through the second transistor, and the audio driving signal is further output to the DC blocking capacitor connected thereto through the output terminal Out of the audio driving signal.

[0134] It can be seen that when the conduction conditions of the first transistor and the second transistor are opposite, only a 1-bit control signal is needed to control the first transistor and the second transistor to be in different states at the same time.

[0135] In an optional implementation, in the noise elimination circuit 100, the first analog switch 103 may be a third transistor, the second analog switch 104 may be a fourth transistor, and the conduction condition of the third transistor is the same as that of the fourth transistor.

[0136] The third transistor and the fourth transistor can both be transistors that can be used as switching devices, such as MOS transistors.

[0137] Since the conduction conditions of the third transistor and the fourth transistor are the same, in order to ensure that only one transistor is in the conduction state at the same time, two control signals are required to control the third transistor and the fourth transistor respectively.

[0138] Correspondingly, the control signal includes a first control signal and a second control signal with opposite values. When the first control signal controls the third transistor to be turned on, the second control signal controls the fourth transistor to be turned off; when the second control signal controls the fourth transistor to be turned on, the first control signal controls the third transistor to be turned off.

[0139] Exemplarily, when the third transistor and the fourth transistor are both NMOS transistors, the first control signal is used to input the gate of the third transistor, and the second control signal is used to input the gate of the second transistor.

[0140] When the driving subcircuit 102 does not output the audio driving signal, the level state of the first control signal is a high level state, and the level state of the second control signal is a low level state. Thus, by inputting the first control signal in a high level state into the gate of the third transistor and the second control signal in a low level state into the gate of the fourth transistor, the third transistor is turned on and the fourth transistor is turned off. At this time, the preset common mode voltage generated by the voltage generating subcircuit 101 can be output to the output terminal Out of the audio driving signal via the third transistor.

[0141] When the driving sub-circuit 102 outputs the audio driving signal, the level state of the first control signal switches from the high level state to the low level state, and the level state of the second control signal switches from the low level state to the high level state.

[0142] Thus, by inputting the first control signal in a low level state into the gate of the third transistor and the second control signal in a high level state into the gate of the fourth transistor, the third transistor is turned off and the fourth transistor is turned on, and the preset common-mode voltage generated by the voltage generating subcircuit 101 will not be output to the output terminal Out of the audio driving signal via the third transistor, while the audio driving signal generated by the driving subcircuit 102 can be transmitted to the output terminal Out of the audio driving signal via the fourth transistor.

[0143] Exemplarily, when the third transistor and the fourth transistor are both PMOS transistors, the first control signal is used to input the gate of the third transistor, and the second control signal is used to input the gate of the fourth transistor.

[0144] When the driving subcircuit 102 does not output the audio driving signal, the level state of the first control signal is a low level state, and the level state of the second control signal is a high level state. Thus, by inputting the first control signal in a low level state into the gate of the third transistor and the second control signal in a high level state into the gate of the fourth transistor, the third transistor is turned on and the fourth transistor is turned off. At this time, the preset common mode voltage generated by the voltage generating subcircuit 101 can be output to the output terminal Out of the audio driving signal via the third transistor.

[0145] When the driving sub-circuit 102 outputs the audio driving signal, the level state of the first control signal switches from the low level state to the high level state, and the level state of the second control signal switches from the high level state to the low level state.

[0146] Thus, by inputting the first control signal in a high level state into the gate of the third transistor and the second control signal in a low level state into the gate of the fourth transistor, the third transistor is turned off and the fourth transistor is turned on, and the preset common-mode voltage generated by the voltage generating subcircuit 101 will not be output to the output terminal Out of the audio driving signal via the third transistor, while the audio driving signal generated by the driving subcircuit 102 can be transmitted to the output terminal Out of the audio driving signal via the fourth transistor.

[0147] It can be seen that in the embodiment of the present disclosure, when the conduction conditions of the third transistor and the fourth transistor are the same, in order to make only one of the third transistor and the fourth transistor in the conduction state at the same time, a first control signal and a second control signal with opposite values ​​are required to simultaneously control the third transistor and the fourth transistor respectively.

[0148] In a second aspect, an embodiment of the present disclosure provides an audio driver chip. Figure 6 A block diagram of the composition of an audio driver chip provided in an embodiment of the present disclosure.

[0149] Reference Figure 6 The embodiment of the present disclosure provides an audio driver chip 600, which includes the above-mentioned noise elimination circuit 100. To avoid repeated description, the specific circuit structure of the noise elimination circuit 100 is not described here.

[0150] In a third aspect, an embodiment of the present disclosure provides a noise elimination method, which is applied to the above-mentioned audio driver chip 600.

[0151] Figure 7 A flowchart of a noise elimination method provided by an embodiment of the present disclosure. Figure 7 , the noise elimination method comprises:

[0152] Step S710: When the driving subcircuit of the audio driving chip does not output the audio driving signal, a control signal is generated to control the first analog switch to be turned on and the second analog switch to be turned off, so that the preset common mode voltage output by the voltage generating subcircuit is transmitted to the output end of the audio driving signal through the first analog switch.

[0153] The control signal may be stored in a storage device such as a register of the audio driver chip. The level state of the control signal depends on whether the driving sub-circuit of the audio driver chip outputs an audio driving signal.

[0154] In some examples, the preset common-mode voltage output by the voltage generating subcircuit is a preset common-mode voltage output by the first voltage-dividing resistor and the second voltage-dividing resistor.

[0155] The voltage generating subcircuit and the driving subcircuit are connected to the same power supply terminal. The voltage generating subcircuit includes a first voltage dividing resistor and a second voltage dividing resistor. The first resistance value of the first voltage dividing resistor is the same as the second resistance value of the second voltage dividing resistor.

[0156] The first end of the first voltage-dividing resistor is connected to the power supply end, the second end of the first voltage-dividing resistor is connected to the second end of the second voltage-dividing resistor and the first analog switch, the first end of the second voltage-dividing resistor is connected to the ground end, and the second end of the second voltage-dividing resistor is connected to the second end of the first voltage-dividing resistor and the first analog switch.

[0157] Correspondingly, the voltage generating subcircuit outputs a preset common mode voltage through the second end of the first voltage dividing resistor and the second end of the second voltage dividing resistor.

[0158] In some examples, the preset common-mode voltage output by the voltage generation subcircuit is a preset common-mode voltage output by an operational amplifier. Accordingly, the voltage generation subcircuit further includes an operational amplifier, and the second end of the first voltage-dividing resistor and the second end of the second voltage-dividing resistor are connected to the first analog switch through the operational amplifier.

[0159] Among them, the second end of the first voltage-dividing resistor and the second end of the second voltage-dividing resistor are respectively connected to the in-phase input terminal of the operational amplifier, which are used to input a preset common-mode voltage to the operational amplifier, and the output terminal of the operational amplifier is respectively connected to the inverting input terminal of the operational amplifier and the first analog switch, which are used to drive the output of the preset common-mode voltage.

[0160] In some examples, the preset common-mode voltage output by the voltage generation subcircuit is a preset common-mode voltage output by a filter capacitor. Accordingly, the voltage generation subcircuit further includes a filter capacitor, a first end of the filter capacitor is connected to the ground end, and a second end of the filter capacitor is connected to the output end of the operational amplifier and the first analog switch; in the process of generating the preset common-mode voltage, the filter capacitor is used to adjust the voltage change speed of the preset common-mode voltage output by the operational amplifier, and transmit the adjusted preset common-mode voltage to the first analog switch.

[0161] Step S720: When the driving sub-circuit outputs the audio driving signal, a control signal is generated to control the second analog switch to be turned on and the first analog switch to be turned off, so that the audio driving signal output by the driving sub-circuit is transmitted to the output end of the audio driving signal through the second analog switch.

[0162] The audio driving signal output by the driving subcircuit is used to drive external loads such as earphone devices.

[0163] When the second analog switch is turned on and the first analog switch is controlled to be disconnected, the audio drive signal generated by the driving sub-circuit will be transmitted to the output end of the audio drive signal through the second analog switch, and then further transmitted to an external load such as a headphone device through a DC blocking capacitor connected to the output end of the audio drive signal.

[0164] In the noise elimination method provided in the embodiment of the present disclosure, when the driving sub-circuit of the audio driving chip does not output the audio driving signal, the voltage generating sub-circuit of the audio driving chip can also generate a preset common-mode voltage and transmit it to the output end of the audio driving signal of the chip. When the driving sub-circuit of the audio driving chip outputs the audio driving signal, through the control of the control signal, the preset common-mode voltage generated by the voltage generating sub-circuit of the audio driving chip will not be transmitted to the output end of the audio driving signal of the chip, but the audio driving signal output by the driving sub-circuit will be transmitted to the output end of the audio driving signal of the chip.

[0165] Therefore, the noise elimination method provided by the embodiment of the present disclosure can enable the output end of the audio driving signal of the audio driving chip to output a stable voltage value under any circumstances, thereby avoiding POP noise caused by voltage mutation on the DC blocking capacitor side.

[0166] In an optional implementation, the first analog switch is a first transistor, the second analog switch is a second transistor, the conduction conditions of the first transistor and the second transistor are opposite, and the number of control signals is one.

[0167] Correspondingly, when the driving sub-circuit of the audio driving chip does not output the audio driving signal, the level state of the control signal is set to a preset value, and the first analog switch is controlled to be turned on and the second analog switch is controlled to be turned off.

[0168] When the driving sub-circuit outputs the audio driving signal, the level state of the control signal is switched to control the second analog switch to be turned on and the first analog switch to be turned off.

[0169] The first transistor and the second transistor can both be transistors that can be used as switching devices, such as MOS transistors.

[0170] It should also be noted that, since the conduction conditions of the first transistor and the second transistor are opposite, an NMOS transistor or a PMOS transistor with opposite conduction conditions can be used as the first transistor and the second transistor. For example, the first transistor is an NMOS transistor and the second transistor is a PMOS transistor. For another example, the first transistor is a PMOS transistor and the second transistor is an NMOS transistor. The embodiments of the present disclosure are not limited to this.

[0171] The preset value of the level state is determined according to the conduction condition of the first transistor. For example, when the first transistor is turned on when the first transistor is at a low level, the preset value is a low level. For another example, when the first transistor is turned on when the first transistor is at a high level, the preset value is a high level.

[0172] Switching the level state of the control signal refers to flipping the level state of the control signal, for example, switching the control signal from a low level to a high level, or switching the control signal from a high level to a low level.

[0173] Exemplarily, when the first transistor is an NMOS transistor and the second transistor is a PMOS transistor, when the driving subcircuit of the audio driving chip does not output an audio driving signal, the level state of the control signal is set to a high level, thereby controlling the first transistor to be turned on and the second transistor to be turned off.

[0174] When the driving sub-circuit outputs the audio driving signal, the level state of the control signal is switched from a high level to a low level, thereby controlling the second transistor to be turned on and the first transistor to be turned off.

[0175] In an optional implementation, the first analog switch is a third transistor, the second analog switch is a fourth transistor, the conduction conditions of the third transistor and the fourth transistor are the same, and the control signal includes a first control signal and a second control signal with opposite values.

[0176] Correspondingly, when the driving subcircuit of the audio driving chip does not output the audio driving signal, the level state of the first control signal is set to the first preset value to control the first analog switch to be turned on, and the level state of the second control signal is set to the second preset value to control the second analog switch to be turned off.

[0177] When the driving sub-circuit outputs the audio driving signal, the level states of the first control signal and the second control signal are switched respectively to control the first analog switch to be disconnected and the second analog switch to be turned on.

[0178] The third transistor and the fourth transistor can both be transistors that can be used as switching devices, such as MOS transistors.

[0179] It should also be noted that, since the conduction conditions of the third transistor and the fourth transistor are the same, transistors of the same type can be used as the third transistor and the fourth transistor. For example, the third transistor and the fourth transistor are both NMOS transistors, and for another example, the third transistor and the fourth transistor are both PMOS transistors, which is not limited in the embodiments of the present disclosure.

[0180] The first preset value and the second preset value are determined according to the conduction conditions of the third transistor and the fourth transistor. For example, when the third transistor and the fourth transistor are turned on when they are at a low level, the first preset value is a low level, and the second preset value is a high level opposite thereto. For another example, when the third transistor and the fourth transistor are turned on when they are at a high level, the first preset value is a high level, and the second preset value is a low level opposite thereto.

[0181] Switching the level states of the first control signal and the second control signal refers to flipping the level states of the first control signal and the second control signal, for example, switching the first control signal from a low level to a high level, and switching the second control signal from a high level to a low level.

[0182] Exemplarily, when the third transistor and the fourth transistor are both NMOS transistors, when the driving sub-circuit of the audio driver chip does not output an audio driving signal, the level state of the first control signal is set to a high level to control the third transistor to be turned on, and the level state of the second control signal is set to a low level to control the fourth transistor to be turned off.

[0183] When the driving subcircuit outputs the audio driving signal, the level state of the first control signal is switched from high level to low level, and the level state of the second control signal is switched from low level to high level, thereby controlling the fourth transistor to be turned on and the third transistor to be turned off.

[0184] The noise elimination method provided in the embodiment of the present invention solves the disadvantage that the existing solution needs to set up additional external circuits outside the chip and is not easy to integrate. The POP noise phenomenon caused by the common-mode voltage jump of the audio driving signal output by the audio driving chip in audio applications is eliminated with a smaller circuit area and lower power consumption.

[0185] The step division of the above methods is only for the purpose of clear description. When implemented, they can be combined into one step or some steps can be split and decomposed into multiple steps. As long as they include the same logical relationship, they are all within the scope of protection of this patent; adding insignificant modifications to the algorithm or process or introducing insignificant designs without changing the core design of the algorithm and process are all within the scope of protection of this patent.

[0186] It will be appreciated by those skilled in the art that all or some of the steps, systems, and functional modules / units in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0187] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0188] Those skilled in the art will understand that although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features from different embodiments is meant to be within the scope of the present embodiment and to form different embodiments.

[0189] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A noise cancellation circuit, It is characterized in that Applied to an audio driver chip, the noise elimination circuit comprises: a voltage generating subcircuit for generating a preset common mode voltage and a driving subcircuit for generating an audio driving signal, wherein a preset voltage value of the preset common mode voltage is determined according to a signal voltage value of a signal common mode voltage of the audio driving signal; The noise elimination circuit further includes: a first analog switch and a second analog switch controlled according to a control signal, the first analog switch being arranged between the voltage generating subcircuit and the output terminal of the audio driving signal, and the second analog switch being arranged between the driving subcircuit and the output terminal of the audio driving signal; Wherein, when the driving subcircuit does not output the audio driving signal, the control signal controls the first analog switch to be turned on and the second analog switch to be turned off, so that the preset common mode voltage output by the voltage generating subcircuit is transmitted to the output end of the audio driving signal through the first analog switch; When the driving sub-circuit outputs an audio driving signal, the control signal controls the second analog switch to be turned on and controls the first analog switch to be turned off, so that the audio driving signal output by the driving sub-circuit is transmitted to the output end of the audio driving signal through the second analog switch.

2. The noise elimination circuit according to claim 1, It is characterized in that The voltage generating subcircuit and the driving subcircuit are connected to the same power supply terminal, and the voltage generating subcircuit comprises a first voltage dividing resistor and a second voltage dividing resistor; a first resistance value of the first voltage dividing resistor is the same as a second resistance value of the second voltage dividing resistor; Wherein, the first end of the first voltage-dividing resistor is connected to the power supply end, and the second end of the first voltage-dividing resistor is connected to the second end of the second voltage-dividing resistor and the first analog switch; A first end of the second voltage-dividing resistor is connected to the ground end, and a second end of the second voltage-dividing resistor is connected to the second end of the first voltage-dividing resistor and the first analog switch; The voltage outputted by the second end of the first voltage-dividing resistor and the second end of the second voltage-dividing resistor is the preset common-mode voltage.

3. The noise elimination circuit according to claim 2, It is characterized in that The voltage generating subcircuit further includes an operational amplifier, and the second end of the first voltage-dividing resistor and the second end of the second voltage-dividing resistor are connected to the first analog switch through the operational amplifier; The second end of the first voltage-dividing resistor and the second end of the second voltage-dividing resistor are respectively connected to the in-phase input terminal of the operational amplifier, so as to input the preset common-mode voltage to the operational amplifier; The output end of the operational amplifier is connected to the inverting input end of the operational amplifier and the first analog switch respectively, and is used to drive and output the preset common mode voltage.

4. The noise elimination circuit according to claim 3, It is characterized in that The voltage generating subcircuit further includes a filter capacitor, a first end of the filter capacitor is connected to the ground end, and a second end of the filter capacitor is connected to the output end of the operational amplifier and the first analog switch; During the generation of the preset common-mode voltage, the filter capacitor is used to adjust the voltage change speed of the preset common-mode voltage output by the operational amplifier.

5. The noise elimination circuit according to any one of claims 1 to 4, It is characterized in that The first analog switch is a first transistor, the second analog switch is a second transistor, and when the conduction conditions of the first transistor and the second transistor are opposite, the number of the control signal is one; When the control signal controls the first transistor to be turned on, the control signal controls the second transistor to be turned off; When the control signal controls the second transistor to be turned on, the control signal controls the first transistor to be turned off.

6. The noise elimination circuit according to any one of claims 1 to 4, It is characterized in that The first analog switch is a third transistor, the second analog switch is a fourth transistor, and when the conduction conditions of the third transistor and the fourth transistor are the same, the control signal includes a first control signal and a second control signal having opposite values; When the first control signal controls the third transistor to be turned on, the second control signal controls the fourth transistor to be turned off; When the second control signal controls the fourth transistor to be turned on, the first control signal controls the third transistor to be turned off.

7. An audio driver chip, It is characterized in that The audio driver chip comprises the noise elimination circuit as described in any one of claims 1-6.

8. A noise elimination method, It is characterized in that The method is applied to the audio driver chip according to claim 7, and the method comprises: When the driving subcircuit of the audio driving chip does not output the audio driving signal, a control signal is generated to control the first analog switch to be turned on and the second analog switch to be turned off, so that the preset common mode voltage output by the voltage generating subcircuit is transmitted to the output end of the audio driving signal through the first analog switch; When the driving sub-circuit outputs the audio driving signal, a control signal is generated to control the second analog switch to be turned on and the first analog switch to be turned off, so that the audio driving signal output by the driving sub-circuit is transmitted to the output end of the audio driving signal through the second analog switch.

9. The noise elimination method according to claim 8, It is characterized in that The first analog switch is a first transistor, the second analog switch is a second transistor, the conduction conditions of the first transistor and the second transistor are opposite, and the number of the control signal is one; When the driving subcircuit of the audio driving chip does not output the audio driving signal, setting the level state of the control signal to a preset value, controlling the first analog switch to be turned on and the second analog switch to be turned off; When the driving sub-circuit outputs the audio driving signal, the level state of the control signal is switched to control the second analog switch to be turned on and the first analog switch to be turned off.

10. The noise elimination method according to claim 8, It is characterized in that The first analog switch is a third transistor, the second analog switch is a fourth transistor, the third transistor and the fourth transistor have the same conduction condition, and the control signal includes a first control signal and a second control signal having opposite values; When the driving subcircuit of the audio driving chip does not output an audio driving signal, the level state of the first control signal is set to a first preset value to control the first analog switch to be turned on, and the level state of the second control signal is set to a second preset value to control the second analog switch to be turned off; When the driving sub-circuit outputs the audio driving signal, the level states of the first control signal and the second control signal are switched respectively to control the first analog switch to be disconnected and the second analog switch to be turned on.

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