CN101924969A - Audio controller capable of depopping and depopping method - Google Patents

Abstract

The invention discloses an audio frequency controller capable of removing sonic booms and a method for removing sonic booms. The method can regulate the driving capability of an amplifier, effectively remove sonic booms and not increase total harmonic distortion (THD). The audio frequency controller comprises the amplifier and a comparator, wherein after receiving and amplifying an audio frequency input signal, the amplifier outputs an audio frequency output signal; the comparator is coupled with the amplifier and receives a switch indicating signal; the comparator compares the switch indicating signal with a reference voltage to generate a comparison signal for controlling the driving capability of the amplifier; and in the method, one switch indicating signal is generated in one work period, and a drive control signal is also generated to respond to the switch indicating signal and control the driving capability of one amplifier for removing sonic booms.

Description

Audio controller capable of depopping and depopping method

technical field

The invention relates to an audio circuit and a method, in particular to a depopping circuit and a method.

Background technique

Audio circuits or audio amplifiers amplify low-power audio signals to drive transducers, such as speakers. Audio circuits usually include an operational amplifier (OP amplifier), and its driving ability can generally be adjusted as needed. For example, when an audio circuit drives a low-impedance device, it is necessary to increase the drive capability of the operational amplifier to reduce its total harmonic distortion (THD).

When the audio circuit is in the transient period when the power is turned on or off, due to the different charging and discharging rates of the capacitors in the circuit, it often causes harsh pop noise. Existing audio amplifiers are designed with consideration of the impedance range of the final speaker to be driven. Low-impedance and high-impedance speakers require different driving capabilities. When the driving capability of the aforementioned operational amplifier increases, the situation of popping sounds will become more severe. Seriously, and when the driving capability of the operational amplifier is reduced, it cannot drive high-impedance speakers, increasing the total harmonic distortion. In other words, it is impossible to simultaneously solve the two issues related to the output sound quality of the audio circuit, total harmonic distortion and popping, by adjusting the driving capability of the operational amplifier of the audio circuit. For example, when the total harmonic distortion is to be reduced, the popping problem is bound to increase; conversely, when the popping problem is to be reduced, the total harmonic distortion is bound to be increased.

In view of the fact that the traditional audio circuit cannot reduce the total harmonic distortion and eliminate the popping sound at the same time, it is urgent to propose a novel audio circuit or controller to achieve the dual purpose of reducing the popping sound and reducing the total harmonic distortion.

Contents of the invention

The technical problem to be solved by the present invention is to provide an audio controller and a depopping method capable of depopping. By adjusting the drive capability of the amplifier, depopping can be effectively removed without increasing total harmonic distortion (THD).

In order to solve the above technical problems, the present invention provides the following technical solutions:

The invention provides an audio controller capable of depopping, including an amplifier and a comparator. The amplifier receives an audio input signal and amplifies it to output an audio output signal. The comparator is coupled to the amplifier and receives a switch indication signal. The comparator compares the switch indication signal with the reference voltage to generate a comparison signal for controlling the driving capability of the amplifier. The depopping circuit may also include a timing control circuit for generating a switch indication signal. The depopping circuit may also include a signal bypass circuit for bypassing the audio output signal to ground during power on/off transients or during silence.

The present invention also provides a method for removing popping sounds, including generating a switch indicating signal according to a working period and generating a driving control signal in response to the switching indicating signal, so as to control the driving capability of an amplifier to remove popping sounds.

In summary, the audio controller and depopping method used in the present invention can effectively achieve the dual purposes of eliminating popping and reducing total harmonic distortion by using a comparator to output a comparison signal to control the drive capability of the amplifier.

The advantages and spirit of the present invention can be further understood through the following descriptions of drawings and specific embodiments.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

FIG. 1 is a schematic diagram of a depopping circuit according to an embodiment of the present invention.

Fig. 2(a) is a waveform diagram of related signals according to an embodiment of the present invention.

FIG. 2( b ) is a waveform diagram of related signals according to another embodiment of the present invention.

Fig. 3 is a flow chart of a de-popping method according to an embodiment of the present invention.

[Description of main component symbols]

Each assembly included in the accompanying drawings of the present invention is listed as follows:

1 Depop circuit

10 Controller

100 Operational Amplifiers

102 Comparator

12 Timing control circuit

14 Signal bypass circuit

31-32 Steps

311-312 Steps

321-322 steps

Detailed ways

FIG. 1 is a de-pop circuit 1 according to an embodiment of the present invention, and FIG. 2( a ) is a waveform diagram of related signals. In this embodiment, the depopping circuit 1 mainly includes a depopping controller (hereinafter referred to as the controller) 10 . The controller 10 can be implemented as a single integrated circuit, or can be combined with other circuits in the same integrated circuit.

In this embodiment, the controller 10 includes an operational amplifier (OP amplifier) 100 and a comparator 102. The operational amplifier 100 receives an audio input signal through an input pin IN, and after it is amplified, it is output through an output pin OUT to The amplified audio output signal is output. In the exemplary circuit of FIG. 1 , a resistor R1 is coupled between the output terminal of the operational amplifier 100 and the inverting input terminal (-), and another resistor R2 is coupled between the inverting input terminal and ground (ground). , and the audio input signal is coupled to the non-inverting input terminal (+) of the operational amplifier 100 . However, the present invention is not limited to the amplifier connection configuration shown in FIG. 1 .

The comparator 102 receives a switch indication signal CT through the control pin. Figure 2(a) illustrates the switch indicator signal CT, its low level (or first level) voltage indicates that the audio circuit is in the momentary period of power on/off, while the high level (or second level) voltage indicates The audio circuit is in a stable normal working period, and the signal slope of the switch indication signal CT changing from low level to high level covers the transition period from power off to on. The switch indication signal CT can be generated by selecting the resistor RCT and the capacitor CCT connected in series in the timing control circuit 12 to determine the charging/discharging rate, so as to generate the switch indication signal CT with different slopes. In other words, the timing control circuit 12 can expand the steep transition signal of the power supply HVDD ( FIG. 2( a )) to form a gentle slope signal such as the switch indication signal CT. In this embodiment, both ends of the capacitor CCT of the timing control circuit 12 can also be connected in parallel with a switching transistor TCT, such as an npn bipolar junction transistor, which can be controlled by a previous stage circuit (not shown), such as The digital TV control chip is used to select whether to enable the timing control circuit 12. For example, if the base of the switching transistor TCT receives a high-level control signal, the timing control circuit 12 can quickly discharge the potential of the switch indication signal CT to a low level, so as to turn off the audio amplification operation of the controller 10; if The base of the switch transistor TCT receives a low-level control signal, and the timing control circuit 12 is started to charge and discharge the switch indication signal CT.

FIG. 2( a ) is a waveform diagram of related signals of the circuit shown in FIG. 1 . The comparator 102 compares the switch indication signal CT with a preset reference voltage (such as the first reference voltage Vref1 in the figure). When the switch indication signal CT is lower than the first reference voltage Vref1 (that is, during the moment when the power is turned on or off), the comparator 102 outputs a low-level driving control signal OP, which controls the operational amplifier 100 to reduce its driving capability ( driving ability), such as the output slew rate (slew rate); when the switch indication signal CT is greater than the first reference voltage Vref1 (that is, during normal operation after the power is turned on or before it is turned off), the comparator 102 outputs a high voltage The flat drive control signal OP controls the operational amplifier 100 to enhance its drive capability. Those skilled in the art can make various possible changes based on the above disclosure. For example, the comparator 102 can compare with a plurality of first reference voltages to generate a multi-bit output to switch the driving capability of the operational amplifier 100 .

Furthermore, the comparator 102 compares the switch indication signal CT with another preset reference voltage (such as the second reference voltage Vref2 in the figure). When the switch indication signal CT is less than the second reference voltage Vref2 (that is, during the moment when the power is turned on or off), the controller 10 also outputs a low-level depopping sound switching signal SWPOP. For example, a general-purpose Type input and output (GPIO) pin or a dedicated pin, which switches the pin to control the signal bypass circuit 14 through the depopping sound switching signal SWPOP, for example, turns on the transistors Q1 and Q2, thus (from the pin OUT) audio output signal OUT is bypassed to ground instead of flowing to the output device (or load). Thereby, the popping sound generated by the transient signal can be effectively removed or reduced. In the circuit shown in the embodiment of FIG. 1 , the signal bypass circuit 14 includes transistors Q1 , Q2 and a plurality of resistors. When the switch indication signal CT is greater than the second reference voltage Vref2, the comparator 102 will output a high-level depop switching signal SWPOP to turn off the transistors Q1 and Q2, so that the signal bypass circuit 14 is disabled, thereby allowing the audio output signal OUT It is output via a normal path, such as via a coupling capacitor C in the figure, to an output device or a load (such as a speaker). In this embodiment, the first reference voltage Vref1 and the second reference voltage Vref2 are used to generate the driving control signal OP and the depopping sound switching signal SWPOP respectively. However, in other embodiments, the same reference voltage can also be used, and the generated driving control signal OP and depop switching signal SWPOP will be the same. When using different reference voltages (for example, using different first reference voltage Vref1 and second reference voltage Vref2), during the instant when the power is turned on or off, since the audio output signal OUT at this time has not yet stabilized, the low power The flat depopping switching signal SWPOP conducts the audio output signal OUT to ground, which can further prevent popping.

According to the above-mentioned embodiment, during the momentary period when the power is turned on or off (or referred to as the de-popping period), the operational amplifier 100 reduces its driving capability through the low-level drive control signal OP, so that it has a better de-popping effect. . As for the normal working period after the power is turned on or before it is turned off, the operational amplifier 100 can increase its driving capability through the high-level driving control signal OP, which can reduce its total harmonic distortion (THD), especially when driving low It is more obvious when the impedance device is used. In other words, the present invention takes into account both sound quality control of depopping and reduction of total harmonic distortion.

FIG. 2( b ) shows a waveform diagram of related signals of the circuit shown in FIG. 1 according to another embodiment of the present invention, which can remove popping sound in mute operation. When the TV performs the operation of turning the channel, it will frequently need to mute and restore the volume. Using the circuit embodiment of FIG. 1 can effectively remove the popping sound. For example, when a TV chip (not shown) receives the channel-turning command, it can announce the ON/OFF control signal in FIG. 1 , as shown in FIG. 2( b ). Please refer to Figure 1 and Figure 2(b) at the same time. When the ON/OFF control signal is pulled from low level to high level through the announcement, the transistor TCT is turned on and grounded, and the switch indication signal CT is also quickly pulled to low level. That is to say, the driving control signal OP makes the driving capability of the operational amplifier 100 be quickly reduced, and the depopping switching signal SWPOP is also quickly pulled to a low level, so that the signal bypass circuit 14 is quickly activated to avoid popping. After a predetermined time, for example, it can be set and adjusted by the system operator, the announcement of the ON/OFF control signal ends, and when it is pulled from high level to low level, the transistor TCT is turned off, and the switch indication signal CT is slowly charged through the capacitor CCT until When the reference voltage Vref is exceeded, the audio input tends to be stable at this time. The driving capability of the operational amplifier 100 is increased, and the popping switching signal SWPOP is used to turn off the signal bypass circuit 14 and normally drive the speaker output, thereby avoiding popping. In this embodiment, if the same reference voltage is used, the generated driving control signal OP and the depop switching signal SWPOP will be the same. However, in other embodiments, different reference voltages can also be used, as shown in FIG. Popping switching signal SWPOP.

Fig. 3 is a flowchart of a de-popping method according to an embodiment of the present invention. First, in step 31, the working period is determined. In one embodiment, as shown in FIG. 2( a ), the "working period" includes the momentary period of power on/off and the normal working period. In another embodiment, as shown in FIG. 2( b ), the "working period" includes a silent period and a non-silent period during the operation of the turntable.

In one embodiment (FIG. 2(a)), the determining step 31 can be implemented by the following steps. Firstly, in the second step 311 , the timing control circuit 12 expands the steep transition signal of the power supply HVDD to generate a gentle slope signal of the switch indication signal CT. Next, in the next step 312 , the comparator 102 compares the switch indication signal CT with a reference voltage (such as the first reference voltage Vref1 ) to determine a power-on/off transient period or a normal working period. When the switch indication signal CT is lower than the first reference voltage Vref1, it is determined as the instantaneous period of power on/off, otherwise it is determined as the normal working period.

In another embodiment (FIG. 2(b)), the determining step 31 is implemented by the following steps. Firstly, in the next step 311 , the ON/OFF control signal is used to generate the switch indication signal CT. When the ON/OFF control signal is pulled from a low level to a high level through the announcement, the switch indicating signal CT is also pulled to a low level rapidly. When the ON/OFF control signal is pulled from a high level to a low level through the announcement, the switch indication signal CT is slowly charged through the capacitor CCT until it exceeds the reference voltage. Next, in the next step 312 , the comparator 102 compares the switch indication signal CT with the reference voltage Vref to determine a silent period or a non-silent period. When the switch indication signal CT is lower than the reference voltage Vref, it is determined as a silent period, otherwise, it is determined as a non-silent period.

Next, in step 32 , the driving capability of the operational amplifier 100 is controlled to perform depopping according to different determination periods. In one embodiment (FIG. 2(a)), this step 32 can be implemented by the following steps. First, in the second step 321, the comparator 102 is used to compare the switch indication signal CT with a reference voltage (such as the first reference voltage Vref1) to generate the drive control signal OP, for example, during the momentary period of power on/off, to generate The low-level driving control signal OP is used to reduce the driving capability of the operational amplifier 100; during normal operation, the high-level driving control signal OP is generated to enhance its driving capability. Next, in the next step 322 , the comparator 102 compares the switch indication signal CT with a reference voltage (eg, the second reference voltage Vref2 ) to control the depopping switch signal SWPOP. The depopping sound switching signal SWPOP can selectively bypass the audio output signal to ground, for example, during the power on/off momentary period, a low level depopping sound switching signal SWPOP is generated to bypass the audio output signal Conducted to the ground to remove or reduce the popping sound; during normal operation, a high-level de-popping sound switching signal SWPOP is generated to allow the audio output signal to be output in a normal path, for example, output to the output device through the coupling capacitor C in Figure 1 ( or load). The steps 321 and 322 can also be performed at the same time or the order is reversed.

In another embodiment (FIG. 2(b)), this step 32 is implemented by the following steps. In the next step 321, the comparator 102 is used to compare the switch indication signal CT and the reference voltage Vref to generate the drive control signal OP. The level of the OP is pulled down to reduce the driving capability of the amplifier; during the non-silent period, a high-level driving control signal OP is generated to enhance its driving capability. In the second step 322, the comparator 102 is used to compare the switch indication signal CT and the reference voltage Vref to control the depopping sound switching signal SWPOP. For example, during the silence period, a low level depopping sound switching signal SWPOP is generated to set The audio output signal is bypassed to the ground to remove the popping sound; during the non-silent period, a high-level de-popping sound switching signal SWPOP is generated to allow the audio output signal to be output through the normal path, for example, output through the coupling capacitor C in Figure 1 to the output device (or load). The steps 321 and 322 can also be performed at the same time or the order is reversed.

In summary, the present invention discloses an audio controller capable of depopping, including an amplifier and a comparator coupled to the amplifier. The amplifier receives an audio input signal through an input pin, amplifies it, and outputs it through an output pin. The pin is used to output an audio output signal; the comparator receives a switch indication signal through a control pin; the comparator compares the switch indication signal with a reference voltage to generate a comparison signal to control the driving capability of the amplifier.

The present invention also discloses a depopping method, which includes the following steps: generating a switch indication signal according to the working period, for example, the switch indicating signal is used to indicate the instantaneous period of power on/off and the normal working period; or, the switch indicating signal Used to indicate silent periods and non-silent periods. The step of generating the switch indication signal is to expand the transition steep slope signal during the power on/off transient period into a gentle slope signal of the switch indication signal; and generating a driving control signal in response to the switch indication signal to control the driving capability of the amplifier To remove the popping sound, for example, by comparing the switch indication signal with the reference voltage to generate a drive control signal, when the drive control signal is at the first level, the drive capability of the amplifier is reduced; and when the drive control signal is at the second level , then enhance the driving capability of the amplifier, for example, during the silence period, by turning on the switching transistor to quickly pull down the level of the switch indication signal to reduce the driving ability of the amplifier, for example, by comparing the switch indication signal and another reference voltage to generate a de-popping switching signal for selectively bypassing the audio output signal to ground, preferably, the level of the other reference voltage is higher than the level of the reference voltage.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the claims of the present invention; all other equivalent changes or modifications that do not deviate from the spirit disclosed by the invention should be included in the described within the claims.

Claims (25)

1. audio controller that can remove sonic boom is characterized in that it comprises:

One amplifier in order to receiving an audio frequency input signal, and amplifies the back to export an audio output signal with it; And

One comparator is coupled to described amplifier, in order to receive a switch index signal;

Wherein, a more described switch index signal of described comparator and a reference voltage are to produce a comparison signal to control the driving force of described amplifier.

2. audio controller as claimed in claim 1, it is characterized in that, described amplifier more comprises an input pin and an output connecting pin, and described amplifier receives described audio frequency input signal via described input pin, and exports described audio output signal via described output connecting pin.

3. audio controller as claimed in claim 2 is characterized in that, described audio controller more comprises a control pin, and described comparator receives described switch index signal via described control pin.

4. audio controller as claimed in claim 1 is characterized in that, described amplifier is an operational amplifier.

5. audio controller as claimed in claim 1 is characterized in that, described switch index signal is in order to indicate during an electric power starting/close instantaneous and a normal work period.

6. audio controller as claimed in claim 1 is characterized in that, described switch index signal in order to indicate one quiet during and one non-quiet during.

7. audio controller as claimed in claim 3 is characterized in that, it can be coupled to a sequential control circuit by described control pin, and described sequential control circuit is in order to produce described switch index signal.

8. audio controller as claimed in claim 7 is characterized in that, described sequential control circuit comprises the resistor and the capacitor of series connection, is connected between a power supply and the ground connection.

9. audio controller as claimed in claim 7 is characterized in that, described sequential control circuit is expanded a transition abrupt slope signal of described power supply a gentle slope signal that forms described switch index signal.

10. audio controller as claimed in claim 8, it is characterized in that, described sequential control circuit more comprises a switching transistor, is connected to the two ends of described capacitor, and wherein said switching transistor is controlled by a front stage circuits to select whether to enable described sequential control circuit.

11. audio controller as claimed in claim 10 is characterized in that, described switching transistor is a npn two-carrier junction transistor.

12. audio controller as claimed in claim 1 is characterized in that, when described comparison signal is one first level, reduces the driving force of described amplifier; And when described comparison signal is one second level, then strengthen the driving force of described amplifier.

13. audio controller as claimed in claim 3 is characterized in that, described output connecting pin can be coupled to a signal bypass circuit, can be in order to described audio output signal grounding shunt.

14. audio controller as claimed in claim 13, it is characterized in that, described comparator more can be by more described switch index signal and another reference voltage and is produced a sonic boom switching signal, whether to control described signal bypass circuit with described audio output signal grounding shunt.

15. audio controller as claimed in claim 14 is characterized in that, the level system of described another reference voltage is higher than the level of described reference voltage.

16. one kind is gone the sonic boom method, it is characterized in that it comprises:

Produce a switch index signal according to a duration of work; And

Produce a drive control signal with in response to described switch index signal, with the driving force of controlling an amplifier to remove sonic boom.

17. the sonic boom method of going as claimed in claim 16 is characterized in that, described switch index signal is in order to indicate during an electric power starting/close instantaneous and a normal work period.

18. the sonic boom method of going as claimed in claim 16 is characterized in that, described switch index signal in order to indicate one quiet during and one non-quiet during.

19. the sonic boom method of going as claimed in claim 16 is characterized in that, the step of described generation switch index signal system is expanded to the transition abrupt slope signal during an electric power starting/close instantaneous the gentle slope signal of one switch index signal.

20. the sonic boom method of going as claimed in claim 16 is characterized in that, the step of described generation drive control signal system by more described switch index signal and a reference voltage to produce described drive control signal.

21. the sonic boom method of going as claimed in claim 16 is characterized in that, when described drive control signal is one first level, reduces the driving force of described amplifier; And when described drive control signal number is one second level, then strengthen the driving force of described amplifier.

22. the sonic boom method of going as claimed in claim 20 is characterized in that the step of described generation drive control signal more comprises:

Go the sonic boom switching signal by more described switch index signal and another reference voltage to produce one.

23. the sonic boom method of going as claimed in claim 22 is characterized in that, the level system of described another reference voltage is higher than the level of described reference voltage.

24. the sonic boom method of going as claimed in claim 22 is characterized in that, the described sonic boom switching signal system of going can be with audio output signal grounding shunt optionally.

25. the sonic boom method of going as claimed in claim 16, it is characterized in that, the step of described generation switch index signal lie in one quiet during by conducting one switching transistor rapidly the level of described switch index signal is dragged down, to reduce the driving force of described amplifier.

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