High-fidelity vehicle-mounted audio processing circuit and processing method

Abstract

The invention belongs to the technical field of integrated circuits, and particularly relates to a high-fidelity vehicle-mounted audio processing circuit and a processing method, which can effectively reduce signal distortion caused by conduction loss of a switch and nonlinearity of an internal amplifier in a transmission process of an input audio signal vin. Therefore, the audio processing circuit can still realize high-fidelity output in a relatively wide working voltage range. The audio processing circuit comprises a large structure prevention module (201), a volume control module (202), a low pitch control module (203), a high pitch control module (204) and an output control and distortion compensation module (205), the output control and distortion compensation module (205) comprises a signal input end vain and a bias voltage end VREF, and resistors R10-R18 are connected in series between the signal input end vain and the bias voltage end VREF. Switches K10, K11, K12... K17 are respectively connected between the self-signal input end vain and the resistor R17, and resistors R20, R21, R22... R24 are connected in series between the output end vmid of the K17 and the bias voltage end VREF.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuits, and in particular relates to a high-fidelity vehicle-mounted audio processing circuit and a processing method. Background Art

[0002] With the rapid development of new energy vehicles, consumers' pursuit of automotive audio-visual entertainment is gradually increasing, and the requirements for the sound quality of car audio output are also getting higher and higher. In order to meet the input signal requirements of the subsequent audio amplifier, the audio processing circuit as the front stage usually has to set a very high working voltage to ensure that the amplitude of the output signal is large enough and the distortion is as small as possible. However, this requires the commonly used board-level voltage (3~5V) to be boosted and then the audio processing chip is powered separately, which increases the cost of the application. Therefore, it is necessary to design an audio processing circuit that can still output high-fidelity signals at low voltage.

[0003] The main structure of the current audio processing circuit is as follows Figure 1 As shown, the input signal υ in After entering the audio processing circuit, it is first pre-amplified in the pre-amplification module 101, and then processed by the volume control module 102, the bass control module 103, and the treble control module 104. Finally, the processed signal v is output by the output control module 105. out The signal is transmitted to the 110 audio power amplifier circuit, and the audio power amplifier drives the 120 speakers for output.

[0004] Input signal v in In the internal transmission process of the audio processing circuit, due to the conduction loss of the switch and the nonlinearity of the amplifier, υ in When passing through each control module, some distortion will be generated. Especially when the operating voltage is low and the input signal amplitude is small, the conduction loss of the switch and the influence of the amplifier nonlinearity will become more obvious. The audio processing circuit converts the distorted signal v out Transmitting the signal to an audio amplifier for amplification will greatly affect the output effect of the car audio. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a high-fidelity vehicle audio processing circuit and processing method, which can effectively reduce the in During the transmission process, the conduction loss of the switch and the distortion caused by the nonlinearity of the internal amplifier enable the audio processing circuit to still achieve high-fidelity output within a wider operating voltage range.

[0006] The technical solution of the present invention is as follows: A high-fidelity vehicle audio processing circuit includes a prevention structure module, a volume control module, a bass control module, a treble control module and an output control and distortion compensation module, wherein the output control and distortion compensation module includes a signal input terminal v ain and bias voltage terminal V REF , where the signal input terminal v ain and bias voltage terminal V REF Resistors R10-R18 are connected in series between the signal input terminals u ain Switches K10, K11, K12, K17 are connected to the resistor R17, and the output terminal υ mid The bias voltage terminal V REF Resistors R20, R21, R22, R24 are connected in series, and the output terminal υ of K17 mid , resistors R20, R21, R22··R24 and bias voltage terminal V REF The connection nodes are connected to one end of switches K20, K21··K24, and K25 respectively, one end of resistor R03 is connected between resistor R24 ​​and switch K25, the other end of resistor R03 is connected to the negative input terminal of amplifier OPA1, the positive input terminal of amplifier OPA1 is connected to the other ends of switches K20, K21··K24, and K25, the other end of resistor R03 is also connected to resistor R01 and resistor R02 respectively, wherein resistor R01 is connected to output terminal v through switch K01. out The resistor R02 is connected to the output terminal υ through the switch K02. out Connect the output of amplifier OPA1 to the output terminal υ out connect.

[0007] As a preferred embodiment, the input signal passes through the prevention structure module, the volume control module, the bass control module and the treble control module, and then provides driving capability through the output control and distortion compensation module and outputs externally. The input AC signal v ain By the bias voltage terminal V REF Provides a DC level. When K10 and K20 are closed, the input signal at the in-phase terminal of amplifier OPA1 is v ain +V REF When K11 and K20 are closed, the input signal at the in-phase terminal of the amplifier OPA1 is (R11+··+R18 / R10+··+R18)υ ain +V REF When K11 and K21 are closed, the input signal amplitude of the amplifier in-phase terminal is (R11+··+R18 / R10+··+R18)(R21+··+R24 / R20+··+R24)v ain +V REFWhen K25 is closed, the amplifier in-phase input bias voltage terminal V REF , the audio control circuit outputs the mute state.

[0008] When the input signal v ain When the amplitude is small, the conduction loss of the switch and the nonlinearity of the internal amplifier cause the input signal υ of the same-direction end of the amplifier OPA1 to pin It is possible that obvious distortion has occurred. At this time, K02 is closed, and the amplifier OPAl is in the same-direction amplification state. The output signal is:

[0009]

[0010] When the input signal amplitude is large, the input signal υpi of the same direction end of the amplifier OPAl n The distortion is small and no large compensation is required. At this time, K01 is closed and the output signal is:

[0011]

[0012] The present invention provides a high-fidelity vehicle-mounted audio processing circuit and a processing method, which can adjust the degree of distortion compensation according to different input signal amplitudes of the audio processing circuit, reduce the distortion of the output signal when the power supply voltage is low, and can be widely applied to high-fidelity audio systems. The main features of the improved technical solution are: Feature 1: The distortion compensation structure is added to widen the operating voltage range of the audio processing circuit and reduce the application cost; Feature 2: The degree of distortion compensation can be adjusted according to the input signal amplitude to achieve high-fidelity output of the signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the main structure of the current audio processing circuit;

[0014] Figure 2 The main structure of the improved audio processing circuit;

[0015] Figure 3 This is the circuit diagram of the output control and distortion compensation module. DETAILED DESCRIPTION

[0016] The present invention discloses an audio processing circuit capable of compensating for signal distortion, which reduces the distortion caused by the conduction loss of a switch and the nonlinearity of an internal amplifier during signal transmission, thereby realizing an audio processing circuit capable of high-fidelity output within a wide operating voltage range.

[0017] To achieve the above purpose, the structure of the audio processing circuit is improved, such as Figure 2A distortion compensation function is added inside the output control and distortion compensation module 205, so that before the signal is output to the audio power amplifier chip, the distortion compensation function can reduce the signal distortion caused by the conduction loss of the previous stage switch and the nonlinearity of the internal amplifier.

[0018] After the input signal passes through the volume control module 201, the volume control module 202, the bass control module 203 and the treble control module 204, it is provided with driving capability by the output control and distortion compensation module 205 and outputted externally. The internal structure of the output control and distortion compensation module 205 is as follows: Figure 3 As shown, the input AC signal v ain By the bias voltage terminal V REF Provides a DC level. When K10 and K20 are closed, the input signal of the amplifier OPAl in-phase terminal is v ain +V REF When K11 and K20 are closed, the input signal at the in-phase terminal of the amplifier OPA1 is (R11+··+R18 / R10+··+R18)υ ain +V REF， When K11 and K21 are closed, the input signal amplitude at the in-phase end of the amplifier is (R11+··+R18 / R10+··+R18)(R21+··+R24 / R20+··+R24)v ain +V REF When K25 is closed, the amplifier in-phase input bias voltage terminal V REF , the audio control circuit outputs the mute state.

[0019] When the input signal v ain When the amplitude is small, the conduction loss of the switch and the nonlinearity of the internal amplifier cause the input signal v at the same direction end of the amplifier OPA1 to pin There may be obvious distortion. At this time, K02 is closed, and the amplifier OPA1 is in the same direction amplification state. The output signal is:

[0020]

[0021] When the input signal amplitude is large, the input signal u pin The distortion is small and no large compensation is required. At this time, K01 is closed and the output signal is:

[0022]

[0023] By applying the above structure, the operating voltage range of the audio processing circuit can be widened, the boost chip on the PCB board is omitted, and the application cost is saved; the degree of distortion compensation can also be adjusted according to the amplitude of the input signal, and the output signal distortion can be flexibly optimized.

[0024] The key technical point of the present invention is to provide an audio processing circuit that can compensate for signal distortion, reduce the distortion caused by the conduction loss of the switch and the nonlinearity of the internal amplifier during the signal transmission process, thereby realizing an audio processing circuit that can perform high-fidelity output within a wide operating voltage range.

[0025] The above generally describes the present invention in detail, but it is obvious to a person skilled in the art that some modifications or improvements can be made to the present invention. Therefore, modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A high-fidelity car audio processing circuit, characterized in that: The invention comprises a prevention structure module (201), a volume control module (202), a bass control module (203), a treble control module (204) and an output control and distortion compensation module (205), wherein the output control and distortion compensation module (205) comprises a signal input terminal v ain and bias voltage terminal V REF , where the signal input terminal v ain and bias voltage terminal V REF Resistors R10-R18 are connected in series, from the signal input terminal v ain Switches K10, K11, K12, K17 are connected to the resistor R17, and the output terminal v of K17 is mid The bias voltage terminal V REF Resistors R20, R21, R22·R24 are connected in series, and the output terminal v of K17 mid , resistors R20, R21, R22··R24 and bias voltage terminal V REF The connection nodes are connected to one end of switches K20, K21··K24, and K25 respectively, one end of resistor R03 is connected between resistor R24 ​​and switch K25, the other end of resistor R03 is connected to the negative input terminal of amplifier OPA1, the positive input terminal of amplifier OPA1 is connected to the other ends of switches K20, K21··K24, and K25, the other end of resistor R03 is also connected to resistor R01 and resistor R02 respectively, wherein resistor R01 is connected to output terminal v through switch K01. out The resistor R02 is connected to the output terminal v through the switch K02. out Connect the output of amplifier OPA1 to the output of V out connect.

2. The high-fidelity vehicle audio processing circuit according to claim 1, characterized in that: After the input signal passes through the prevention structure module (201), the volume control module (202), the bass control module (203) and the treble control module (204), the output control and distortion compensation module (205) provides driving capability and outputs the input AC signal v ain By the bias voltage terminal V REF Provides a DC level. When K10 and K20 are closed, the input signal at the in-phase terminal of amplifier OPA1 is v ain +V REF When K11 and K20 are closed, the input signal at the in-phase terminal of the amplifier OPA1 is (R11+··+R18 / R10+··+R18)v ain +V REF When K11 and K21 are closed, the input signal amplitude of the amplifier in-phase terminal is (R11+··+R18 / R10+··+R18)(R21+··+R24 / R20+··+R24)v ain +V REF When K25 is closed, the amplifier in-phase input bias voltage terminal V REF , the audio control circuit outputs the mute state. When the input signal v ain When the amplitude is small, the conduction loss of the switch and the nonlinearity of the internal amplifier cause the input signal v at the same direction end of the amplifier OPA1 to pin There may be obvious distortion. At this time, K02 is closed, and the amplifier OPA1 is in the same direction amplification state. The output signal is: When the input signal amplitude is large, the input signal v pin The distortion is small and no large compensation is required. At this time, K01 is closed and the output signal is:

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