TWI426787B - Audio compensation apparatus - Google Patents

Description

Audio compensation device

The present invention relates to the field of electronic technologies, and in particular, to an audio compensation device.

Due to the nonlinear nature of the electronics, the frequency response curve of the audio amplifier is usually flat in the mid-range, while the low-frequency and high-frequency portions are significantly reduced. That is, when the audio amplifier amplifies the audio signal, it usually causes the gain of the audio signal to decrease in the low frequency part and the high frequency part.

As we all know, for audio signals, the details and contours of the music are mainly done by the high-frequency part. The gain of the audio signal in the high-frequency part is reduced, which will make the music details blurry and lack transparency. The reduction of the gain of the audio signal in the low frequency portion will cause the bass to be difficult to be reflected, resulting in distortion when playing the audio signal.

In view of this, it is necessary to provide an audio compensation device that can compensate for audio signals.

An audio compensation device for receiving an audio signal from a signal source input. The audio compensation device includes a detection control unit and a compensation unit. The detection control unit is configured to detect the frequency of the audio signal, and generate a first level signal when the frequency of the audio signal is in the first frequency range, and the frequency of the audio signal. A second level signal is generated when in the second frequency range. The compensation unit includes an electronic switch, a first compensation circuit and a second compensation circuit, and the electronic switch switches the first compensation circuit pair according to the first level signal switching The first frequency range portion of the audio signal is compensated, and the electronic switch further selects the second compensation circuit to compensate the second frequency range portion of the audio signal according to the second level signal switching.

The audio compensation device is configured to provide a detection control circuit, an electronic switch, a first compensation circuit, and a second compensation circuit, when the detection control circuit detects that the frequency of the audio signal is in the first frequency range and the second frequency range. The first level signal and the second level signal are respectively generated, the electronic switch selects the first compensation circuit to compensate the audio signal according to the first level signal switching, and the electronic switch switches the second compensation circuit to the audio according to the second level signal switching. The signal is compensated, so that the audio signal is better in sound quality during playback without distortion.

200‧‧‧Audio compensation device

10‧‧‧Signal source

20‧‧‧Detection Control Unit

24‧‧‧Compensation unit

30‧‧‧Audio amplification unit

40‧‧‧Power amplification unit

50‧‧‧Speakers

242‧‧‧First compensation circuit

240‧‧‧Electronic switch

245‧‧‧second compensation circuit

R1, R2, R3, R4‧‧‧ resistance

U1‧‧‧Detection Wafer

Vcc, V _Ref , Ui, Uo‧‧‧ voltage

A1‧‧‧Operational Amplifier

A2‧‧‧ frequency selector

C1, C2, C3, C4‧‧‧ capacitors

244‧‧‧ Third compensation circuit

1 is a functional block diagram of an audio compensation device according to a preferred embodiment, the audio compensation device including a compensation unit.

2 is a functional block diagram of the compensation unit of FIG. 1.

3 is a detailed circuit diagram of the audio compensation device of FIG. 1.

Referring to FIG. 1 , the audio compensation device 200 of the preferred embodiment is configured to receive an audio signal provided by the signal source 10 to perform frequency compensation on the audio signal, and provide the compensated audio signal to the audio amplification unit 30 . The audio amplifying unit 30 is configured to perform signal amplification processing on the compensated audio signal. The power amplifying unit 40 is configured to perform power amplification processing on the amplified audio signal and provide it to the speaker 50 for playing.

The audio compensation device 200 includes a detection control unit 20 and a compensation unit 24. The detection control unit 20 is configured to detect an audio signal input from the signal source 10 to obtain a frequency f _{i of} the audio signal. The detection control unit 20 is preset with a high reference frequency f _H1 , a high reference frequency f _Href , a low reference frequency f _{L1 ,} and a low reference frequency f _Lref . The detection control unit 20 is further configured to calculate the frequency f _{i of the} audio signal and the low reference frequency f _L1 to obtain a low operation frequency f _L2 and compare the low operation frequency f _L2 with the low reference frequency f _Lref . When the low operation frequency f _{L2 is} greater than zero and less than the low reference frequency f _Lref , the detection control unit 20 outputs the first level signal. In this embodiment, the detection control unit 20 is configured to subtract the frequency f _{i of the} audio signal from the low reference frequency f _L1 , that is, the low operation frequency f _L2 =f _i -f _L1 , and 0<f _L2 =f _i -f _L1 <f _Lref . Therefore, when the frequency f _i of the audio signal is in the first frequency range, that is, f _L1 <f _i <f _L1 +f _Lref , the detection control unit 20 generates the first level signal.

The detection control unit 20 is further configured to calculate the audio signal frequency f _i and the high reference frequency f _H1 to obtain a high operation frequency f _H2 and compare the high operation frequency f _H2 with the high reference frequency f _Href . When the high operation frequency f _{H2 is} greater than zero and less than the high reference frequency f _Href , the detection control unit 20 outputs the second level signal. In this embodiment, the detection control unit 20 is configured to subtract the frequency f _{i of the} audio signal from the low reference frequency f _H1 , that is, the low operation frequency f _H2 =f _i -f _H1 , and 0<f _H2 =f _i -f _H1 <f _Href . Therefore, when the frequency f _i of the audio signal is in the second frequency range, that is, when f _H1 <f _i <f _H1 +f _Href , the detection control unit 20 generates the second level signal. The frequency range of the audio signal is 20Hz~20KHz. When the high reference frequency f _H1 =10KHz, the high reference frequency f _Href =3KHz, the low reference frequency f _L1 =50Hz and the low reference frequency f _Lref =100Hz, it can be obtained when 50Hz< When f _i <150 Hz, the detection control unit 20 generates a first level signal; when 10 KHz < f _i <13 KHz, the detection control unit 20 generates a second level signal. In this embodiment, the first frequency range is a low frequency range and the second frequency range is a high frequency range.

Referring to FIG. 2 together, the compensation unit 24 includes an electronic switch 240, a first compensation circuit 242, a third compensation circuit 244, and a second compensation circuit 245. In the present embodiment, the first compensation circuit 242 is a low frequency compensation circuit, the second compensation circuit 245 is a high frequency compensation circuit, and the third compensation circuit 244 is an intermediate frequency compensation circuit. The electronic switch 240 is configured to receive the first level signal, and select the first compensation circuit 242 to operate according to the first level signal switching to compensate the low frequency portion of the audio signal, thereby compensating for distortion of the audio signal in the low frequency portion.

The electronic switch 240 is further configured to receive the second level signal, and select the second compensation circuit 245 according to the second level signal switching to compensate the high frequency portion of the audio signal, thereby compensating the audio signal in the high frequency portion. distortion.

The electronic switch 240 does not perform the switching selection action when the first level signal or the second level signal is not received. At this time, the third compensation circuit 244 starts to work to compensate the middle frequency band of the audio signal, thereby compensating for the distortion of the audio signal in the middle frequency band, so that the audio compensation device 200 compensates the audio signal more perfectly, so that the speaker 50 plays the audio signal. Better sound quality.

Referring to FIG. 3, the detection control unit 20 includes a detection chip U1. The detection chip U1 includes a signal input terminal 6 and a control terminal 25. The signal input terminal 6 is connected to the signal source 10, and the control terminal 25 is connected to the electronic switch 240. The detection chip U1 is pre-set with a high reference frequency f _H1 , a high reference frequency f _Href , a low reference frequency f _{L1 ,} and a low reference frequency f _Lref , and the detection chip U1 is used for the frequency f _{i of the} audio signal and the low reference frequency f _L1 performs a subtraction operation to determine whether the frequency f _i is in the first frequency range, and outputs the first level signal through the control terminal 25 when the frequency f _{i is} in the first frequency range. The detecting chip U1 is further configured to subtract the frequency f _{i of the} audio signal from the high reference frequency f _H1 to determine whether the frequency f _i is in the second frequency range, and to control when the frequency f _{i is} in the second frequency range Terminal 25 outputs a second level signal.

The compensation unit 24 includes an operational amplifier A1, a frequency selector A2, a feedback resistor R1, a frequency selective resistor R2, a pull-down resistor R3, a pull-up resistor R4, a first capacitor C1, a second capacitor C2, and a third capacitor C3. The non-inverting input of the operational amplifier A1 is connected to the signal source 10, and the feedback resistor R1 is connected between the inverting input terminal of the operational amplifier A1 and its output terminal. The non-inverting input of the frequency selector A2 is connected to the reference voltage V _Ref through a pull-up resistor R4, and the inverting input terminal of the frequency selector A2 is connected to its output terminal. The non-inverting input of the frequency selector A2 is also grounded by the third capacitor C3, the electronic switch 240 and the pull-down resistor R3. The second capacitor C2 is connected between the electronic switch 240 and the inverting input of the operational amplifier A1. One end of the first capacitor C1 is connected between the third capacitor C3 and the electronic switch 240, and the other end is connected to the inverting input terminal of the operational amplifier A1. One end of the frequency selective resistor R2 is connected between the third capacitor C3 and the electronic switch 240, and the other end is connected to the inverting input terminal of the frequency selector A2.

The working principle of the audio compensation device 200 is as follows: when the electronic switch 240 does not receive the first level signal or the second level signal, the electronic switch 240 cuts off the electrical connection between the third capacitor C3 and the pull-down resistor R3, respectively. The electrical connection between the second capacitor C2 and the third capacitor C3. Therefore, the AC path of the portion of the frequency selector A2 is such that the first capacitor C1 and the frequency selective resistor R2 are connected in series and grounded to form a third compensation circuit 244. The total impedance of the first capacitor C1 and the frequency selective resistor R2 in series is Z1. The non-inverting input of the operational amplifier A1 receives the audio signal input from the signal source 10, the voltage amplitude of the audio signal is Ui, and the output voltage of the operational amplifier A1 is Uo. The gain of operational amplifier A1 is A=Uo/Ui=(R1+Z1)/Z1=1+R1/Z1. Since the series resonant circuit composed of the capacitor C1 and the frequency selective resistor R2 oscillates, that is, the resonant frequency The total impedance Z1 is the smallest, that is, Z1=R2, and the gain A=1+R1/Z1=1+R1/R2 is the largest. In this embodiment, the resonant frequency It is in the IF frequency range, so it can compensate the audio signal in the IF frequency range.

When the electronic switch 240 receives the first level signal, the electronic switch 240 turns on the electrical connection between the second capacitor C2 and the third capacitor C3, and cuts off the electrical connection between the third capacitor C3 and the pull-down resistor R3. . Therefore, the AC path of the portion of the frequency selector A2 is such that the first capacitor C1 is connected in parallel with the second capacitor C2 and then connected in series with the frequency selective resistor R2 to ground to form the first compensation circuit 244. The total impedance of the first capacitor C1 in parallel with the second capacitor C2 and in series with the frequency selective resistor R2 is Z2. The gain A of the operational amplifier A1 is Uo/Ui=(R1+Z2)/Z2=1+R1/Z2. When the series resonant circuit composed of the first capacitor C1, the second capacitor C2, and the frequency selective resistor R2 oscillates, that is, the resonant frequency The total impedance Z2 is the smallest, that is, Z2=R2, and the gain A=1+R1/Z2=1+R1/R2 is the largest. In this embodiment, the resonant frequency Relative to It becomes smaller, and f2 is in the low frequency range, so that the compensation of the audio signal in the low frequency range can be realized.

When the electronic switch 240 receives the second level signal, the electronic switch 240 turns on the electrical connection between the third capacitor C3 and the pull-down resistor R3, and cuts off the electrical connection between the second capacitor C2 and the third capacitor C3. . Therefore, the AC path of the portion of the frequency selector A2 is a pull-down resistor R3 connected in parallel with the frequency selective resistor R2 and then connected in series with the first capacitor C1 to constitute a second compensation circuit 245. The total impedance of the pull-down resistor R3 in parallel with the frequency selective resistor R2 and in series with the first capacitor C1 is Z3. The gain of operational amplifier A1 is A=Uo/Ui=(R1+Z3)/Z3=1+R1/Z3. The impedance of the frequency selective resistor R2 in parallel with the pull-down resistor R3 is Rz. When the series resonant circuit composed of the frequency selective resistor R2, the pull-down resistor R3, and the first capacitor C1 oscillates, that is, the resonant frequency The total impedance Z3 is the smallest, that is, Z3=Rz, and the gain A=1+R1/Z1=1+R1/Rz is the largest. In this embodiment, since the impedance Rz of the frequency selective resistor R2 and the pull-down resistor R3 is less than R2, the resonant frequency Relative to When it becomes larger, f3 is in the high frequency range, so that the compensation of the audio signal in the high frequency range can be realized.

In other embodiments, the first capacitor C1 is a tunable capacitor, and the frequency selective resistor R2 is a variable resistor. By adjusting the capacitance value of the first capacitor C1 or the resistance value of the frequency selective resistor R2, the pair of different high frequency frequencies can be realized. And the distortion compensation of the audio signals of different low frequency frequencies, thus meeting different needs.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and those skilled in the art who are familiar with the art of the present invention should be included in the following claims.

200‧‧‧Audio compensation device

10‧‧‧Signal source

20‧‧‧Detection Control Unit

30‧‧‧Audio amplification unit

40‧‧‧Power amplification unit

50‧‧‧Speakers

Claims (9)

An audio compensation device for receiving an audio signal from a signal source, wherein the audio compensation device comprises a detection control unit and a compensation unit, wherein the detection control unit is configured to detect the frequency of the audio signal, The first level signal is generated when the frequency of the audio signal is in the first frequency range, and the second level signal is generated when the frequency of the audio signal is in the second frequency range, the compensation unit includes an electronic switch, a first compensation circuit, and a second a compensation circuit, wherein the electronic switch selects a first compensation circuit to compensate for a first frequency range portion of the audio signal according to the first level signal switching, and the electronic switch further switches the second compensation circuit to the audio according to the second level signal switching The second frequency range portion of the signal is compensated; the compensation unit includes an operational amplifier, a frequency selector, a feedback resistor, a frequency selective resistor, a pull-down resistor, a pull-up resistor, a first capacitor, a second capacitor, and a third capacitor, and the operational amplifier The non-inverting input is connected to the signal source, and the feedback resistor is connected to the inverting input terminal of the operational amplifier and its output The non-inverting input of the frequency selector is connected to the reference voltage by a pull-up resistor, and the inverting input end of the frequency selector is connected to the output end thereof, and the non-inverting input end of the frequency selector is further provided by the third capacitor and the electronic The switch and the pull-down resistor are grounded. The second capacitor is connected between the electronic switch and the inverting input terminal of the operational amplifier. One end of the first capacitor is connected between the third capacitor and the electronic switch, and the other end is connected to the inverting of the operational amplifier. At the input end, one end of the frequency selective resistor is connected between the third capacitor and the electronic switch, and the other end is connected to the inverting input terminal of the frequency selector. The audio compensation device of claim 1, wherein the first frequency range comprises a low frequency range, and the second frequency range comprises a high frequency range The first compensation circuit includes a first compensation circuit, and the second compensation circuit includes a second compensation circuit. The audio compensation device of claim 1, wherein the compensation unit further comprises a third compensation circuit that does not perform a switching selection action when the electronic switch does not receive the first level signal or the second level signal, The third compensation circuit compensates the audio signal. The audio compensation device of claim 1, wherein the detection control unit is preset with a high reference frequency, a high reference frequency, a low reference frequency, and a low reference frequency, and the detection control unit is configured to use an audio signal. The frequency is operated with a low reference frequency to obtain a low operating frequency, and when the low operating frequency is greater than zero and less than the low reference frequency, the detecting control unit outputs the first level signal; the detecting control unit is further configured to The frequency of the audio signal is calculated with a high reference frequency to obtain a high operating frequency, and when the high operating frequency is greater than zero and less than the high reference frequency, the detecting control unit outputs the second level signal. The audio compensation device of claim 4, wherein the detection control unit comprises a detection chip, wherein the detection chip is preset with a high reference frequency, a high reference frequency, a low reference frequency, and a low reference frequency. The detecting chip includes a signal input end and a control end, and the signal input end is connected to the signal source, and the control end is connected to the electronic switch, wherein the detecting chip is used for subtracting the frequency of the audio signal from the low reference frequency, and The control terminal outputs a first level signal, and the detection chip is used for subtracting the frequency of the audio signal from the high reference frequency, and outputting the second level signal by the control terminal. The audio compensation device of claim 1, wherein the electronic switch separates between the pull-down resistor and the third capacitor when the first level signal and the second level signal are not received. Electrical connection and second capacitance An electrical connection with the third capacitor. The audio compensation device of claim 1, wherein the electronic switch cuts off the electrical connection between the pull-down resistor and the third capacitor when receiving the first level signal, and turns on the second capacitor and the third Electrical connection between capacitors. The audio compensation device of claim 1, wherein the electronic switch cuts off the electrical connection between the second capacitor and the third capacitor when receiving the second level signal, and turns on the pull-down resistor and the third Electrical connection between capacitors. The audio compensation device of claim 1, wherein the first capacitor is a tunable capacitor, and the frequency selective resistor is a variable resistor.