Single-ended and differential output audio driver circuits and related POP sound removal methods

Abstract

The present application relates to a single-ended, differential output audio driver circuit and a method for removing related pop-up noise. In the single-ended output audio driver circuit, the negative input terminal of a first operational amplifier is respectively connected to the first end of a fourth resistor and to the first input terminal through the first resistor, the positive input terminal is respectively connected to the second input terminal through the second resistor and to ground through the third resistor, and the output terminal is connected to a first node; the first node is respectively connected to the second end of the fourth resistor and to the second node through the first switch and to the third switch; the second node is respectively connected to the second end of the fourth resistor and to ground through the fifth resistor; the third switch includes N switch units connected in parallel; each switch unit includes a switch and a resistor connected in series, where N is an integer greater than or equal to 2. This method can solve the pop-up noise that exists during circuit power-up and power-down, as well as the pop-up noise caused by the operational amplifier's own imbalance, thereby improving the user experience.

Description

Technical Field

[0001] The present application relates to the technical field of POP sound removal, and in particular to a single-ended, differential output audio driving circuit and a related POP sound removal method. Background Art

[0002] With the popularity of mobile devices, integrated high-performance audio headphone amplifiers are becoming increasingly common, and 16-ohm or 32-ohm headphone drivers are becoming the norm. To ensure good sound quality, headphone driver amplifiers must have very low noise and harmonic distortion, while also being free of other unwanted noises such as popping.

[0003] Popping noise refers to the popping sound caused by transient impacts during power-up, power-down, and after power-on stabilization of audio devices. There are two main sources of popping noise. One is that during the establishment of the negative feedback loop of the operational amplifier, the output signal is unstable, resulting in a sudden signal jump. This signal jump is clearly detectable by the human ear at a voltage as low as 1mV, significantly affecting the listening experience. The other is that after the negative feedback loop of the operational amplifier is established, the operational amplifier generates an offset voltage, which is directly transmitted to the output in the form of a jump, causing the popping sound.

[0004] In the related art, the POP sound can be eliminated by using a larger DC blocking capacitor in the circuit structure, but the required DC blocking capacitor is mostly an off-chip capacitor, which is not conducive to circuit integration. In addition, this method can be used to solve the POP sound existing in the circuit power supply, but it cannot solve the POP sound caused by the offset voltage generated by the operational amplifier itself. In actual use, the POP sound caused by an offset voltage of 1mV can be noticed by people. If it is not calibrated, the offset of the operational amplifier can easily exceed 1mV. Even if it can be calibrated, it will waste a lot of chip area resources, power consumption and subsequent testing resources. The operation is complicated and it is difficult to achieve the ideal effect. Summary of the Invention

[0005] In view of this, the purpose of this application is to overcome the shortcomings of the existing technology and provide a single-ended, differential output audio driving circuit and a method for removing related POP sounds.

[0006] To achieve the above objectives, this application adopts the following technical solutions:

[0007] A first aspect of the present application provides a single-ended output audio driver circuit, comprising: a first operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first switch, a second switch, and a third switch; wherein the negative input terminal of the first operational amplifier is respectively connected to the first end of the fourth resistor and to the first input terminal via the first resistor, the positive input terminal is respectively connected to the second input terminal via the second resistor and to ground via the third resistor, and the output terminal is connected to a first node; the first node is respectively connected to the second end of the fourth resistor via the first switch and to the second node via the third switch; the second node is respectively connected to the second end of the fourth resistor via the second switch and to ground via the fifth resistor;

[0008] The third switch includes N switch units connected in parallel; each switch unit includes a switch and a resistor connected in series, and N is an integer greater than or equal to 2.

[0009] Optionally, the impedances of the resistors in the first switch unit to the Nth switch unit in the N switch units decrease in sequence from high to low.

[0010] A second aspect of the present application provides a method for removing POP sound of a single-ended output, which is applied to the single-ended output audio driving circuit as described in the first aspect of the present application, and the method comprises:

[0011] During power-up of the single-ended audio output circuit, the first switch is closed and the first operational amplifier is turned on at a first moment; starting from a second moment, the switches of the N switch units in the third switch are closed in sequence at a first preset time interval until all are turned on; the second switch is closed at a third moment, and the first switch is turned off at a fourth moment; wherein the fourth moment is later than the third moment, the third moment is later than the second moment, and the second moment is later than the first moment;

[0012] During power-off of the single-ended audio output circuit, the first switch is closed at a fifth moment, the second switch is opened at a sixth moment, and starting from a seventh moment, the switches of the N switch units in the third switch are sequentially opened at a second preset time interval until all are opened, and the first switch is opened and the first operational amplifier is turned off at an eighth moment; the eighth moment is later than the seventh moment, the seventh moment is later than the sixth moment, and the sixth moment is later than the fifth moment.

[0013] Optionally, when the impedances of the resistors in the first to Nth switch units among the N switch units decrease sequentially from high to low, closing the switches of the N switch units in the third switch unit in sequence until all of them are turned on includes: closing the switches of the first to Nth switch units in the third switch unit in sequence until all of them are turned on;

[0014] Sequentially disconnecting the switches of the N switch units in the third switch until all are disconnected includes: sequentially closing the switches from the Nth switch unit to the first switch unit in the third switch until all are disconnected.

[0015] According to a third aspect of the present application, there is provided a differential output audio driving circuit, comprising: a second operational amplifier, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a fourth switch, a fifth switch, a sixth switch, a seventh switch, an eighth switch, and a ninth switch; wherein the negative input terminal of the second operational amplifier is respectively connected to the first end of the ninth resistor and to the third input terminal through the sixth resistor, the positive input terminal is respectively connected to the fourth input terminal through the seventh resistor and to the first end of the eleventh resistor through the eighth resistor, the first output terminal is connected to the third node, the second output terminal is connected to the fourth node, the fourth node is respectively connected to the second end of the eleventh resistor through the seventh switch and to the fifth node through the ninth switch; the third node is respectively connected to the second end of the ninth resistor through the fourth switch and to the sixth node through the sixth switch; the sixth node is respectively connected to the second end of the ninth resistor through the fifth switch and to the fifth node through the tenth resistor; the first end of the eighth switch is connected to the fifth node, and the second end is connected to the second end of the eleventh resistor;

[0016] The sixth switch includes M switch circuits connected in parallel; each switch circuit includes a switch and a resistor connected in series, where M is an integer greater than or equal to 2;

[0017] The ninth switch includes K switch modules connected in parallel; each switch module includes a switch and a resistor connected in series, and K is an integer greater than or equal to 2.

[0018] Optionally, the impedances of the resistors in the first switch circuit to the Mth switch circuit in the M switch circuits decrease in sequence from high to low.

[0019] Optionally, the impedances of the resistors in the first switch module to the Kth switch module in the K switch modules decrease in sequence from high to low.

[0020] A fourth aspect of the present application provides a method for removing POP sound of a differential output, which is applied to the differential output audio driving circuit as described in the third aspect of the present application, and the method comprises:

[0021] During power-on of the differential output audio output circuit, at a ninth moment, the fourth switch and the seventh switch are closed, and the second operational amplifier is turned on. Starting from a tenth moment, at a third preset time interval, the switches of the M switch circuits in the sixth switch circuit are sequentially closed until all are turned on. Simultaneously, the switches of the K switch modules in the ninth switch circuit are sequentially closed until all are turned on. At an eleventh moment, the fifth switch and the eighth switch are closed, and at a twelfth moment, the fourth switch and the seventh switch are opened. The twelfth moment is later than the eleventh moment, the eleventh moment is later than the tenth moment, and the tenth moment is later than the ninth moment.

[0022] During power-off of the differential audio output circuit, the fourth switch and the seventh switch are closed at the thirteenth moment, and the fifth switch and the eighth switch are opened at the fourteenth moment. Starting from the fifteenth moment, at a fourth preset time interval, the switches of the M switch circuits in the sixth switch circuit are sequentially opened until all are opened. Simultaneously, the switches of the K switch modules in the ninth switch circuit are sequentially opened until all are opened. At the sixteenth moment, the fourth switch and the seventh switch are opened, and the second operational amplifier is turned off. The sixteenth moment is later than the fifteenth moment, which is later than the fourteenth moment, which is later than the thirteenth moment.

[0023] Optionally, when the impedances of the resistors in the first to the M-th switch circuits in the M switch circuits decrease sequentially from high to low, closing the switches of the M switch circuits in the sixth switch circuit in sequence until all of them are turned on includes: closing the switches of the first to the N-th switch circuit in the sixth switch circuit in sequence until all of them are turned on;

[0024] Sequentially disconnecting the switches of the M switch circuits in the sixth switch until all are disconnected includes: sequentially closing the switches from the Mth switch circuit to the first switch circuit in the sixth switch until all are disconnected.

[0025] Optionally, when the impedances of the resistors in the first to Kth switch modules among the K switch modules decrease sequentially from high to low, closing the switches of the K switch modules in the ninth switch module in sequence until all of them are turned on includes: closing the switches of the first to Kth switch modules in the ninth switch module in sequence until all of them are turned on;

[0026] Sequentially disconnecting the switches of the K switch modules in the ninth switch until all of them are disconnected includes: sequentially closing the switches from the Kth switch module to the first switch module in the ninth switch until all of them are disconnected.

[0027] The technical solution provided by this application may have the following beneficial effects:

[0028] In the solution of this application, by adding a first switch, a second switch, and a third switch to the audio output signal path of the audio driver circuit, it is possible to resist transient pulse signals generated during power-up or power-down. By using N switch units connected in parallel, it is possible to eliminate the impact of the offset voltage generated by the operational amplifier on pop-up sound. By adjusting the on-resistance of the first, second, and third switches and placing them within a feedback loop, the nonlinearity of the third switch can be attenuated through the feedback loop, thereby improving the linearity of the single-ended output audio driver circuit. This solution not only solves the pop-up sound that occurs during power-up and power-down of the circuit, but also solves the pop-up sound caused by the offset voltage generated by the operational amplifier itself. It is simple to operate, saves resources, and improves the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 This is a circuit diagram of a single-ended output audio driver circuit provided by an embodiment of the present application.

[0031] Figure 2 This is a circuit diagram of a third switch provided in another embodiment of the present application.

[0032] Figure 3 This is a circuit diagram of a differential output audio driving circuit provided by another embodiment of the present application.

[0033] Figure 4 This is a circuit diagram of a sixth switch provided in another embodiment of the present application.

[0034] Figure 5 This is a circuit diagram of a ninth switch provided in another embodiment of the present application. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions of this application will be described in detail below. Obviously, the embodiments described are only some of the embodiments of this application, rather than all of them. Based on the embodiments in this application, all other implementation methods obtained by ordinary technicians in this field without making any creative work are within the scope of protection of this application.

[0036] See also Figure 1 FIG1 is a circuit diagram of a single-ended output audio driver circuit provided in one embodiment of the present application. The embodiment of the present application provides a single-ended output audio driver circuit. As shown in the figure, the single-ended output audio driver circuit may specifically include: a first operational amplifier A1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first switch S1, a second switch S2, and a third switch S3.

[0037] The negative input terminal 1 of the first operational amplifier A1 is connected to the first end of the fourth resistor R4, and the ... P1 The positive input terminal 2 is connected to the second input terminal V through the second resistor R2. n1 Connected to the ground through the third resistor R3, the output terminal 3 is connected to the first node V X Connection; First Node V X The first switch S1 is connected to the second end of the fourth resistor R4, and the third switch S3 is connected to the second node V Y Connection; Second node V Y They are respectively connected to the second end of the fourth resistor R4 through the second switch S2 and grounded through the fifth resistor R5.

[0038] like Figure 2 As shown, the third switch S3 may include N switch units connected in parallel; each switch unit may include a switch and a resistor connected in series, where N is an integer greater than or equal to 2.

[0039] During implementation, the more switch units there are in the third switch S3, that is, the larger N is, the finer the jump step is, and the better the effect of removing POP sound is.

[0040] In this embodiment, by adding a first switch S1, a second switch S2, and a third switch S3 to the audio output signal path of the audio driver circuit, transient pulse signals generated during power-up and power-down can be resisted. By using N switch units connected in parallel, the effect of the offset voltage generated by the operational amplifier on pop-up sound can be eliminated. Adjusting the on-resistance of the first, second, and third switches S1, S2, and S3 and placing them within a feedback loop can attenuate the nonlinearity of the third switch S3 through the feedback loop, thereby improving the linearity of the single-ended output audio driver circuit. This approach not only addresses pop-up sound during power-up and power-down, but also addresses pop-up sound caused by the offset voltage generated by the operational amplifier itself. The operation is simple, resource-saving, and user experience is improved.

[0041] In practical applications, the fifth resistor R5 can be an equivalent resistor of a load headphone. At the negative input terminal of the first operational amplifier A1, there is an offset voltage of the first operational amplifier A1. The first node V X is the output node of the first operational amplifier A1, and the second node V Y is the voltage node of the fifth resistor R5, that is, when the fifth resistor R5 is a load earphone, the second node V Y The voltage fluctuation will be transmitted to the human ear through the earphone, so removing the POP sound is to eliminate the voltage fluctuation of the second node V Y A voltage generated that is audible to the human ear.

[0042] In some embodiments, the impedances of the resistors in the first to Nth switch units among the N switch units decrease in sequence from high to low.

[0043] In a specific implementation, the impedance of the resistors in the N switch units of the third switch S3 from the first switch unit to the Nth switch unit is arranged from high to low. For example, if N is 4, the impedances of the resistors in the Nth switch unit from the first switch unit to the Nth switch unit in the third switch S3 are Z1, Z2, Z3, and Z4, respectively, where Z1>Z2>Z3>Z4. In this way, when the third switch S3 is closed or turned on, the on-resistance of the third switch S3 can be gradually changed, thereby better eliminating the impact of the offset voltage of the first operational amplifier A1 on the POP sound.

[0044] Preferably, the impedances of the resistors in the first to Nth switch units of the N switch units can decrease in a gradient from high to low. For example, when N is 4 and the impedances of the first to fourth switch units in the third switch S3 are Z1, Z2, Z3, and Z4, respectively, Z1=2Z2=4Z3=8Z4.

[0045] An embodiment of the present application provides a method for removing POP sound with single-ended output, which is applied to a single-ended output audio driving circuit as described in any of the above embodiments. The specific method for removing POP sound with single-ended output can include two methods, which are applied during the power-on process and the power-off process of the single-ended output audio driving circuit respectively.

[0046] During the power-up process of the single-ended audio output circuit, the first switch S1 is closed and the first operational amplifier A1 is turned on at a first moment. Starting from a second moment, the switches of the N switch units in the third switch S3 are closed in sequence according to a first preset time interval until all are turned on. At a third moment, the second switch S2 is closed, and at a fourth moment, the first switch S1 is turned off. The fourth moment is later than the third moment, the third moment is later than the second moment, and the second moment is later than the first moment.

[0047] In specific implementation, there is no input signal, that is, the first input terminal V P1 and the second input terminal V n1 The differential signal is zero, the first switch S1, the second switch S2, and the third switch S3 are all disconnected, and the first operational amplifier A1 is turned off, indicating a first initial state. During the power-up process of the single-ended audio output circuit, the first switch S1 is first closed and the first operational amplifier A1 is turned on at a first moment, so that the first operational amplifier A1 enters a negative feedback operating mode (closed loop). Subsequently, the first operational amplifier A1 begins to power up. In this case, under the suppression of the negative feedback loop, the first operational amplifier A1 can stabilize the output voltage at the output common-mode voltage after a period of settling time. Since the third switch S3 is disconnected at this time, the first operational amplifier A1 is at the first node V during the settling process. X The generated offset voltage will not be transmitted to the second node V Y After the first operational amplifier A1 is established, the first node V X The voltage at the point is the offset voltage of the first operational amplifier A1. At the second moment, the switches of the N switch units in the third switch S3 are closed in sequence until all are turned on, so as to realize a gradual turn-on from high impedance to low impedance, so as to reduce the voltage of the first node V X The offset voltage value is slowly transmitted to the second node V Y After the conduction is completed, the second switch S2 is closed at the third moment to prepare for the conduction of the outer loop feedback. Finally, the first switch S1 is opened at the fourth moment, so that the feedback loop passes through the third switch S3. The feedback loop attenuates the nonlinearity of the third switch S3. At this time, the switch that contributes to the nonlinearity of the feedback loop is only the second switch S2. At this point, the second node V Y During the power-on process, no large voltage signal is generated, so the second node V Y The voltage generated at the point passes through the load headphones and human ears, and no POP sound is generated.

[0048] Among the N switch units, the impedances of the resistors in the first switch unit to the Nth switch unit may decrease in sequence from high to low.

[0049] Furthermore, when the switches of the N switch units in the third switch S3 are closed in sequence until all are turned on, the switches of the N switch units may be closed in sequence according to a first preset time interval to ensure stable voltage conduction.

[0050] Specifically, the first preset time interval can be set according to actual needs and is not limited here.

[0051] During power-off of the audio output circuit, the first switch S1 is closed at the fifth moment, the second switch S2 is opened at the sixth moment, and starting from the seventh moment, the switches of the N switch units in the third switch S3 are sequentially opened at a second preset time interval until all are opened. At the eighth moment, the first switch S1 is opened and the first operational amplifier A1 is turned off. The eighth moment is later than the seventh moment, the seventh moment is later than the sixth moment, and the sixth moment is later than the fifth moment.

[0052] In specific implementation, there is no input signal, that is, the first input terminal V P1 and the second input terminal V n1 The differential signal is zero, the first switch S1 is opened, the second switch S2 and the third switch S3 are closed, and the first operational amplifier A1 is turned on, which serves as the second initial state. During the power-down process of the single-ended audio output circuit, the first switch S1 is closed first, and then the second switch S2 is opened. At this time, the feedback loop established by the first operational amplifier A1 is taken over by the first switch, that is, the feedback loop changes from external loop to internal loop. Then, the switches of the N switch units in the third switch S3 are opened in sequence until all are opened, and the first node V X and the second node V Y Finally, the first switch S1 is opened and the first operational amplifier A1 is turned off.

[0053] Among the N switch units, the impedances of the resistors in the first switch unit to the Nth switch unit may decrease in sequence from high to low.

[0054] Furthermore, when the switches of the N switch units in the third switch S3 are sequentially turned off until all are turned off, the switches of the N switch units may be sequentially turned off at a second preset time interval to ensure stable voltage isolation.

[0055] Specifically, the second preset time interval can be set according to actual needs and is not limited here.

[0056] In some embodiments, when the impedance of the resistors in the N switch units, from the first switch unit to the Nth switch unit, decreases from high to low, closing the switches of the N switch units in the third switch S3 in sequence until all are turned on may be done by closing the switches of the first switch unit to the Nth switch unit in the third switch S3 in sequence until all are turned on. Similarly, opening the switches of the N switch units in the third switch S3 in sequence until all are turned off may be done by closing the switches of the Nth switch unit to the first switch unit in the third switch S3 in sequence until all are turned off.

[0057] The embodiment of the present application provides an audio driving circuit with differential output, such as Figure 3 As shown, the differential output audio driving circuit may specifically include: a second operational amplifier A2, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a fourth switch S4, a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, and a ninth switch S9; wherein the negative input terminal 4 of the second operational amplifier A2 is respectively connected to the first end of the ninth resistor R9, and to the third input terminal V through the sixth resistor R6. P2 The positive input terminal 5 is connected to the fourth input terminal V through the seventh resistor R7. n2 The first output terminal 6 is connected to the third node V1, the second output terminal 7 is connected to the fourth node V2, the fourth node V2 is connected to the second end of the eleventh resistor R11 through the seventh switch S7 and to the fifth node V3 through the ninth switch S9, and the fifth node V3 is connected to the first end of the eighth switch S8; the third node V1 is connected to the second end of the ninth resistor R9 through the fourth switch S4 and to the sixth node V4 through the sixth switch S6; the sixth node V4 is connected to the second end of the ninth resistor R9 through the fifth switch S5 and to the fifth node V3 through the tenth resistor R10; and the second end of the eighth switch S8 is connected to the second end of the eleventh resistor R11.

[0058] like Figure 4 As shown, the sixth switch S6 includes M switch circuits connected in parallel; each switch circuit includes a switch and a resistor connected in series, and M is an integer greater than or equal to 2.

[0059] like Figure 5 As shown, the ninth switch S9 includes K switch modules connected in parallel; each switch module includes a switch and a resistor connected in series, and K is an integer greater than or equal to 2.

[0060] In this embodiment, by adding a fourth switch S4, a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, and a ninth switch S9 to the audio output signal path of the audio driver circuit, transient pulse signals generated during power-up and power-down can be resisted. By using M switch circuits and K switch modules connected in parallel as the sixth switch S6 and the ninth switch S9, respectively, the effect of the offset voltage generated by the operational amplifier on pop-up sound can be eliminated. By adjusting the on-resistance of each switch and placing them within a feedback loop, the nonlinearity of the sixth switch S6 and the ninth switch S9 can be attenuated through the feedback loop, thereby improving the linearity of the differential output audio driver circuit. This approach not only eliminates pop-up sound during circuit power-up and power-down, but also eliminates pop-up sound caused by the offset voltage generated by the operational amplifier itself. The operation is simple, resource-saving, and user experience is improved.

[0061] In practical applications, the tenth resistor can be an equivalent resistor of a headphone load. At the negative input terminal of the second operational amplifier A2, there is an offset voltage of the second operational amplifier A2. The differential node V1-V2 is the output node of the second operational amplifier A2, and the differential node V3-V4 is the voltage node of the tenth resistor. That is, when the tenth resistor is a headphone load, the voltage fluctuation of the differential node V3-V4 will be transmitted to the human ear through the headphone. Therefore, removing the POP sound means eliminating the voltage generated by the differential node V3-V4 during power-on or power-off that can be heard by the human ear.

[0062] In some embodiments, the impedances of the resistors in the first to Mth switching circuits among the M switching circuits may decrease in sequence from high to low.

[0063] In a specific implementation, the impedances of the resistors in the first to Mth switch circuits of the sixth switch S6 can decrease in descending order. For example, if M is 6, the impedances of the resistors in the first to sixth switch circuits of the sixth switch S6 can be Z1, Z2, Z3, Z4, Z5, and Z6, respectively, such that Z1>Z2>Z3>Z4>Z5>Z6. In this way, when the sixth switch S6 is closed or turned on, the on-resistance of the sixth switch S6 can be gradually changed, thereby better eliminating the impact of the offset voltage of the first operational amplifier A1 on the POP sound.

[0064] Preferably, the impedances of the resistors in the first to Mth switch circuits of the M switch circuits can decrease in a gradient from high to low. For example, when M is 6 and the impedances of the resistors in the first to sixth switch circuits of the sixth switch S6 are Z1, Z2, Z3, Z4, Z5, and Z6, respectively, Z1 = 2, Z2 = 4, Z3 = 8, Z4 = 16, Z5 = 32, Z6.

[0065] In some embodiments, the impedances of the resistors in the first to Kth switch modules among the K switch modules may decrease in sequence from high to low.

[0066] In a specific implementation, the impedances of the resistors in the first through the Kth switch modules of the ninth switch S9 can decrease in descending order. For example, if K is 7, the impedances of the resistors in the first through the seventh switch modules of the ninth switch S9 are Z1, Z2, Z3, Z4, Z5, Z6, and Z7, respectively, such that Z1>Z2>Z3>Z4>Z5>Z6>Z7. In this way, when the ninth switch S9 is closed or turned on, the on-resistance of the ninth switch S9 can be gradually changed, thereby better eliminating the effect of the offset voltage of the first operational amplifier A1 on the POP sound.

[0067] Preferably, the impedances of the resistors in the first to Kth switch modules among the K switch modules can decrease in a gradient from high to low. For example, when K is 7 and the impedances of the first to seventh switch modules in the ninth switch S9 are Z1, Z2, Z3, Z4, Z5, Z6, and Z7, respectively, Z1=2, Z2=4, Z3=8, Z4=16, Z5=32, Z6=64, and Z7.

[0068] An embodiment of the present application provides a method for removing POP sound of differential output, which is applied to the differential output audio driving circuit as described in any of the above embodiments. The method for removing POP sound of differential output may specifically include:

[0069] During power-on of the audio output circuit, at the ninth moment, the fourth switch S4 and the seventh switch S7 are closed, and the second operational amplifier A2 is turned on. Starting from the tenth moment, the switches of the M switch circuits in the sixth switch S6 are closed sequentially until all are turned on. Simultaneously, the switches of the K switch modules in the ninth switch S9 are closed sequentially until all are turned on. At the eleventh moment, the fifth switch S5 and the eighth switch S8 are closed, and at the twelfth moment, the fourth switch S4 and the seventh switch S7 are opened. The twelfth moment is later than the eleventh moment, the eleventh moment is later than the tenth moment, and the tenth moment is later than the ninth moment.

[0070] In specific implementation, there is no input signal, that is, the third input terminal V P2 and the fourth input terminal V n2The differential signal is zero, and the fourth, fifth, sixth, seventh, eighth, and ninth switches S4, S5, S6, S7, S8, and S9 switches are all disconnected. The second operational amplifier A2 is turned off, entering the third initial state. During the power-up process of the differential audio output circuit, the fourth and seventh switches S4, S7, and S7 are first closed at time nine, and the second operational amplifier A2 is turned on, putting the second operational amplifier A2 into negative feedback mode (closed loop). Subsequently, the second operational amplifier A2 begins to power up. Under the suppression of the negative feedback loop, the second operational amplifier A2 stabilizes its output voltage at the output common-mode voltage after a settling time. Because the sixth and ninth switches S6 and S9 are disconnected at this point, the offset voltage generated by the second operational amplifier A2 at V1-V2 during the settling process is not transmitted to the differential node V3-V4.

[0071] After the second operational amplifier A2 completes its settling, the voltage at the differential node V1-V2 becomes the offset voltage of the second operational amplifier A2. Starting at the tenth moment, the M switch circuits in the sixth switch S6 are sequentially closed until all are conductive. Simultaneously, the K switch modules in the ninth switch S9 are sequentially closed until all are conductive, achieving a gradual transition from high impedance to low impedance. This gradually transfers the offset voltage at the differential node V1-V2 to the third differential node V3-V4, like a staircase. After this transition is complete, the fifth switch S5 and the eighth switch S8 are closed at the eleventh moment, preparing for the activation of the outer feedback loop. Finally, the fourth switch S4 and the seventh switch S7 are opened at the twelfth moment, allowing the feedback loop to pass through the sixth switch S6 and the ninth switch S9. The feedback loop attenuates the nonlinearity of the sixth and ninth switches S6 and S9. At this point, the only switches contributing to the nonlinearity of the feedback loop are the fifth and eighth switches S5 and S8. At this point, the differential node V1-V2 does not generate a large voltage signal during the power-on process, so the voltage generated at the differential node V3-V4 passes through the load headphones and the human ear, and does not generate a POP sound.

[0072] Among them, the impedances of the resistors in the first switch circuit to the Mth switch circuit in the M switch circuits may decrease in sequence from high to low.

[0073] Furthermore, when the switches of the M switch circuits in the sixth switch S6 are closed in sequence until all are turned on, the switches of the M switch circuits may be closed in sequence according to a third preset time interval to ensure stable voltage conduction.

[0074] Similarly, the impedances of the resistors in the first switch module to the Kth switch module among the K switch modules may decrease in sequence from high to low.

[0075] Furthermore, when the switches of the K switch modules in the ninth switch S9 are closed in sequence until all are turned on, the switches of the K switch modules may be closed in sequence according to a third preset time interval to ensure stable voltage conduction.

[0076] The third preset time interval can be set according to actual needs and is not limited here.

[0077] During power-off of the audio output circuit, the fourth switch S4 and the seventh switch S7 are closed at the thirteenth moment, the fifth switch S5 and the eighth switch S8 are opened at the fourteenth moment, and starting from the fifteenth moment, the switches of the M switch circuits in the sixth switch S6 are sequentially opened until all are opened. Simultaneously, the switches of the K switch modules in the ninth switch S9 are sequentially opened until all are opened. At the sixteenth moment, the fourth switch S4 and the seventh switch S7 are opened, and the second operational amplifier A2 is turned off. The sixteenth moment is later than the fifteenth moment, which is later than the fourteenth moment, which is later than the thirteenth moment.

[0078] In specific implementation, there is no input signal, that is, the third input terminal V P2 and the fourth input terminal V n2 When the differential signal reaches zero, the fourth switch S4 and the seventh switch S7 are opened, the fifth switch S5, the sixth switch S6, the eighth switch S8, and the ninth switch S9 are closed, and the second operational amplifier A2 is turned on, representing the fourth initial state. During the power-down process of the differential audio output circuit, at time thirteen, the fourth switch S4 and the seventh switch S7 are first closed, followed by time fourteen, when the fifth switch S5 and the eighth switch S8 are opened. At this point, the feedback loop established by the second operational amplifier A2 is taken over by the fourth switch S4 and the seventh switch S7, transitioning from an external feedback loop to an internal feedback loop. Starting at time fifteen, the switches of the M switch circuits in the sixth switch S6 are sequentially opened until all are disconnected. Simultaneously, the switches of the K switch modules in the ninth switch S9 are sequentially opened until all are disconnected, gradually isolating the differential node V1-V2 from the differential node V3-V4. Finally, at time sixteen, the fourth switch S4 and the seventh switch S7 are opened, and the second operational amplifier A2 is turned off.

[0079] Among them, the impedances of the resistors in the first switch circuit to the Mth switch circuit in the M switch circuits may decrease in sequence from high to low.

[0080] Furthermore, when the switches of the M switch circuits in the sixth switch S6 are sequentially turned off until all of them are turned off, the switches of the M switch circuits may be sequentially turned off at a fourth preset time interval to ensure stable voltage isolation.

[0081] Similarly, the impedances of the resistors in the first switch module to the Kth switch module among the K switch modules may decrease in sequence from high to low.

[0082] Furthermore, when the switches of the K switch modules in the ninth switch S9 are sequentially turned off until all are turned off, the switches of the K switch modules may be sequentially turned off at a fourth preset time interval to ensure stable voltage isolation.

[0083] The fourth preset time interval can be set according to actual needs and is not limited here.

[0084] In some embodiments, when the impedances of the resistors in the first to M-th switch circuits in the M switch circuits decrease sequentially from high to low, closing the switches of the M switch circuits in the sixth switch circuit S6 sequentially until all are turned on may be accomplished by closing the switches of the first to N-th switch circuits in the sixth switch circuit S6 sequentially until all are turned on. Similarly, opening the switches of the M switch circuits in the sixth switch circuit S6 sequentially until all are turned off may be accomplished by closing the switches of the M-th switch circuit to the first switch circuit in the sixth switch circuit S6 sequentially until all are turned off.

[0085] Accordingly, when the impedances of the resistors in the first to Kth switch modules among the K switch modules decrease sequentially from high to low, the switches of the K switch modules in the ninth switch S9 are sequentially closed until all are turned on, which can be achieved by sequentially closing the switches of the first to Kth switch modules in the ninth switch S9 until all are turned on. The switches of the K switch modules in the ninth switch S9 are sequentially opened until all are turned off, which can be achieved by sequentially closing the switches of the Kth switch module to the first switch module in the ninth switch S9 until all are turned off.

[0086] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0087] It should be noted that, in the description of this application, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0088] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0089] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0090] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0091] In addition, the functional units in the various embodiments of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into a module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0092] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0093] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0094] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for removing POP sound of single-ended output, characterized in that: In an audio driver circuit for single-ended output, the audio driver circuit for single-ended output includes: a first operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first switch, a second switch, and a third switch; wherein the negative input terminal of the first operational amplifier is respectively connected to the first end of the fourth resistor and to the first input terminal through the first resistor, the positive input terminal is respectively connected to the second input terminal through the second resistor and to ground through the third resistor, and the output terminal is connected to a first node; the first node is respectively connected to the second end of the fourth resistor and to the second node through the first switch and to the third switch; the second node is respectively connected to the second end of the fourth resistor and to ground through the fifth resistor; the third switch includes N switch units connected in parallel; each switch unit includes a switch and a resistor connected in series, where N is an integer greater than or equal to 2; the method includes: During power-up of the single-ended audio output circuit, the first switch is closed and the first operational amplifier is turned on at a first moment; starting from a second moment, the switches of the N switch units in the third switch are closed in sequence at a first preset time interval until all are turned on; the second switch is closed at a third moment, and the first switch is turned off at a fourth moment; wherein the fourth moment is later than the third moment, the third moment is later than the second moment, and the second moment is later than the first moment; During power-off of the single-ended audio output circuit, the first switch is closed at a fifth moment, the second switch is opened at a sixth moment, and starting from a seventh moment, the switches of the N switch units in the third switch are sequentially opened at a second preset time interval until all are opened, and the first switch is opened and the first operational amplifier is turned off at an eighth moment; the eighth moment is later than the seventh moment, the seventh moment is later than the sixth moment, and the sixth moment is later than the fifth moment.

2. The method for removing POP sound of single-ended output according to claim 1, characterized in that: When the impedances of the resistors in the first to Nth switch units in the N switch units decrease sequentially from high to low, closing the switches of the N switch units in the third switch unit in sequence until all of them are turned on, comprises: closing the switches of the first to Nth switch units in the third switch unit in sequence until all of them are turned on; Sequentially disconnecting the switches of the N switch units in the third switch until all are disconnected includes: sequentially closing the switches from the Nth switch unit to the first switch unit in the third switch until all are disconnected.

3. The method for removing POP sound of single-ended output according to claim 1, characterized in that: The impedances of the resistors in the first to Nth switch units of the N switch units decrease in sequence from high to low.

4. A differential output audio driver circuit, characterized in that: include: a second operational amplifier, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a fourth switch, a fifth switch, a sixth switch, a seventh switch, an eighth switch, and a ninth switch; wherein the negative input terminal of the second operational amplifier is respectively connected to the first end of the ninth resistor and to the third input terminal through the sixth resistor, the positive input terminal is respectively connected to the fourth input terminal through the seventh resistor and to the first end of the eleventh resistor through the eighth resistor, the first output terminal is connected to the third node, the second output terminal is connected to the fourth node, the fourth node is respectively connected to the second end of the eleventh resistor through the seventh switch and to the fifth node through the ninth switch; the third node is respectively connected to the second end of the ninth resistor through the fourth switch and to the sixth node through the sixth switch; the sixth node is respectively connected to the second end of the ninth resistor through the fifth switch and to the fifth node through the tenth resistor; the first end of the eighth switch is connected to the fifth node, and the second end is connected to the second end of the eleventh resistor; The sixth switch includes M switch circuits connected in parallel; each switch circuit includes a switch and a resistor connected in series, where M is an integer greater than or equal to 2; The ninth switch includes K switch modules connected in parallel; each switch module includes a switch and a resistor connected in series, and K is an integer greater than or equal to 2.

5. The audio driving circuit with differential output according to claim 4, characterized in that: The impedances of the resistors in the first switch circuit to the Mth switch circuit in the M switch circuits decrease in sequence from high to low.

6. The audio driving circuit with differential output according to claim 4, characterized in that: The impedances of the resistors in the first switch module to the Kth switch module in the K switch modules decrease in sequence from high to low.

7. A method for removing POP sound of differential output, characterized in that: Applied to the audio driving circuit with differential output according to any one of claims 4 to 6, the method comprises: During power-on of the differential output audio output circuit, at a ninth moment, the fourth switch and the seventh switch are closed, and the second operational amplifier is turned on. Starting from a tenth moment, at a third preset time interval, the switches of the M switch circuits in the sixth switch circuit are sequentially closed until all are turned on. Simultaneously, the switches of the K switch modules in the ninth switch circuit are sequentially closed until all are turned on. At an eleventh moment, the fifth switch and the eighth switch are closed, and at a twelfth moment, the fourth switch and the seventh switch are opened. The twelfth moment is later than the eleventh moment, the eleventh moment is later than the tenth moment, and the tenth moment is later than the ninth moment. During power-off of the differential audio output circuit, the fourth switch and the seventh switch are closed at the thirteenth moment, and the fifth switch and the eighth switch are opened at the fourteenth moment. Starting from the fifteenth moment, at a fourth preset time interval, the switches of the M switch circuits in the sixth switch circuit are sequentially opened until all are opened. Simultaneously, the switches of the K switch modules in the ninth switch circuit are sequentially opened until all are opened. At the sixteenth moment, the fourth switch and the seventh switch are opened, and the second operational amplifier is turned off. The sixteenth moment is later than the fifteenth moment, which is later than the fourteenth moment, which is later than the thirteenth moment.

8. The method for removing POP sound of differential output according to claim 7, characterized in that: When the impedances of the resistors in the first to the M-th switch circuits in the M switch circuits decrease sequentially from high to low, closing the switches of the M switch circuits in the sixth switch circuit in sequence until all of them are turned on, comprises: closing the switches of the first to the N-th switch circuit in the sixth switch circuit in sequence until all of them are turned on; Sequentially disconnecting the switches of the M switch circuits in the sixth switch until all are disconnected includes: sequentially closing the switches from the Mth switch circuit to the first switch circuit in the sixth switch until all are disconnected.

9. The method for removing POP sound of differential output according to claim 7, characterized in that: When the impedances of the resistors in the first to Kth switch modules among the K switch modules decrease sequentially from high to low, closing the switches of the K switch modules in the ninth switch module in sequence until all of them are turned on, comprises: closing the switches of the first to Kth switch modules in the ninth switch module in sequence until all of them are turned on; Sequentially disconnecting the switches of the K switch modules in the ninth switch until all of them are disconnected includes: sequentially closing the switches from the Kth switch module to the first switch module in the ninth switch until all of them are disconnected.

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