CN203423792U - Audio circuit and audio system - Google Patents
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- CN203423792U CN203423792U CN201320471161.XU CN201320471161U CN203423792U CN 203423792 U CN203423792 U CN 203423792U CN 201320471161 U CN201320471161 U CN 201320471161U CN 203423792 U CN203423792 U CN 203423792U
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Abstract
The utility model relates to an audio circuit and an audio system. The audio circuit comprises: a ramp signal generation module for generating a digital ramp voltage signal and a first control signal, wherein the voltage change of the digital ramp voltage signal over time satisfies a predetermined function relationship; a selection module for selecting and passing the digital ramp voltage signal according to the first control signal; a digital-to-analog converter for converting the digital ramp voltage signal into an analog ramp voltage signal; and an amplifying module for spending a predetermined time to smoothly rise the voltage of the analog ramp voltage signal to a first common-mode voltage. The ramp signal generation module is used to generate a second control signal after the predetermined time. The selection module is used to select and pass a digital audio signal according to the second control signal. The digital-to-analog converter is used to convert the digital audio signal into an analog audio signal. The amplifying module is used to amplify and output the analog audio signal. According to the utility model, the change of the output voltage of the amplifying module can be controlled accurately, so that the POP noise of the audio device can be eliminated.
Description
Technical Field
The utility model relates to an audio frequency field especially relates to an audio circuit and audio system.
Background
POP noise refers to noise similar to "POP" emitted by an audio device, and is a POP sound generated by momentary impact due to various operations after the audio device is powered on, powered off, or stabilized. As shown in fig. 1, which is a schematic diagram of an operating principle of an audio device in the prior art, a digital-to-analog converter 11 converts a digital audio signal into an analog audio signal, performs power amplification through a power amplifier 12, and inputs the analog audio signal into an audio playing device 14 through an ac coupling capacitor 13 to generate sound. The alternating current coupling capacitor 13 is used for blocking direct current and alternating current, namely blocking an audio direct current signal and passing the audio alternating current signal; the capacitance of the ac coupling capacitor 13 is usually over several tens of microfarads, and if the capacitance is too small, the audio signal is accordingly attenuated. When the power amplifier 12 is powered on or the input point a suddenly changes, the voltage at the output point B suddenly changes, and the voltage at the point C suddenly changes due to the ac coupling capacitor 13, so that POP noise is generated by the audio playing device.
SUMMERY OF THE UTILITY MODEL
The utility model provides an audio circuit and audio system for realize the output voltage's of accurate control amplifier module change, thereby eliminate audio equipment's POP noise.
The utility model provides an audio circuit, include:
the device comprises a ramp signal generation module, a first control module and a second control module, wherein the ramp signal generation module is used for generating a digital ramp voltage signal and a first control signal, and the change of the voltage of the digital ramp voltage signal along with time meets a preset functional relation;
the selection module is connected with the ramp signal generation module and used for selecting the digital ramp voltage signal to block the digital audio signal according to the first control signal;
the digital-to-analog converter is connected with the selection module and used for converting the digital ramp voltage signal into an analog ramp voltage signal;
the amplifying module is connected with the digital-to-analog converter and used for smoothly increasing the voltage of the analog ramp voltage signal to a first common-mode voltage in a preset time;
the ramp signal generating module is further used for generating a second control signal after the preset time;
the selection module is further used for selecting to pass through the digital audio signal and block the digital ramp voltage signal according to the second control signal;
the digital-to-analog converter is also used for converting the digital audio signal into an analog audio signal;
the amplifying module is also used for amplifying and outputting the analog audio signal.
The utility model also provides an audio system, include: audio circuit, alternating current coupling electric capacity and audio playback equipment, audio circuit includes aforementioned audio circuit.
In the audio circuit of the present invention, the ramp signal generating module generates a digital ramp voltage signal and a first control signal, wherein the voltage of the digital ramp voltage signal satisfies a predetermined functional relationship with respect to time; the selection module selects a digital ramp voltage signal to block the digital audio signal according to the first control signal; the digital-to-analog converter converts the digital ramp voltage signal into an analog ramp voltage signal; the amplifying module takes a preset time to smoothly increase the voltage of the analog ramp voltage signal to a first common-mode voltage; the ramp signal generating module generates a second control signal after a predetermined time; the selection module selects to pass through the digital audio signal and block the digital ramp voltage signal according to the second control signal; the digital-to-analog converter converts the digital audio signal into an analog audio signal; the amplifying module amplifies and outputs the analog audio signal. The audio circuit of the utility model can accurately control the output voltage of the amplifying module to change along with the change of the digital slope voltage signal, effectively avoid the voltage and signal mutation phenomenon in the audio circuit, and obviously eliminate the POP noise; the utility model discloses an audio circuit has still realized output voltage common mode and has established and export audio signal's difunctional multiplexing to circuit structure is simple, and the process controllability is strong.
Drawings
FIG. 1 is a schematic diagram of the operation of an audio device according to the prior art;
fig. 2 is a schematic structural diagram of an embodiment of the audio circuit of the present invention;
fig. 3 is a schematic diagram illustrating a shape of a digital ramp voltage signal in the audio circuit shown in fig. 2 according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a first structure of an amplifying module in the audio circuit shown in fig. 2 according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a second structure of the amplifying module in the audio circuit shown in fig. 2 according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an embodiment of the audio system of the present invention;
fig. 7 is a schematic flow chart of an embodiment of the method for eliminating POP noise according to the present invention.
Detailed Description
The invention is further described with reference to the drawings and the detailed description.
As shown in fig. 2, for the structural schematic diagram of the embodiment of the audio circuit of the present invention, the audio circuit may include: a ramp signal generating module 21, a selecting module 22, a digital-to-analog converter 11 and an amplifying module 23; the selection module 22 is connected to the ramp signal generation module 21, the digital-to-analog converter 11 is connected to the selection module 22, and the amplification module 23 is connected to the digital-to-analog converter 11.
The ramp signal generating module 21 is configured to generate a digital ramp voltage signal and a first control signal, where a change of a voltage of the digital ramp voltage signal with time satisfies a predetermined functional relationship; optionally, the voltage of the digital ramp voltage signal varies with time to satisfy a linear, exponential, or logarithmic relationship; fig. 3 is a schematic diagram of the shape of the digital ramp voltage signal in the audio circuit shown in fig. 2 according to the embodiment of the audio circuit of the present invention; the horizontal axis is time, the vertical axis is voltage, the time required for the voltage to rise from 0 to the first common mode voltage is T, and the rising time T is controllable; the selection module 22 is configured to select to block the digital audio signal by the digital ramp voltage signal according to the first control signal; the digital-to-analog converter 11 is configured to convert the digital ramp voltage signal into an analog ramp voltage signal; the amplifying module 23 is configured to take a predetermined time to smoothly increase the voltage of the analog ramp voltage signal to the first common mode voltage; alternatively, the predetermined time may be T, which is the time required for the voltage of the analog ramp voltage signal to rise from 0 to the first common mode voltage; the ramp signal generating module 21 is further configured to generate a second control signal after a predetermined time; the selection module 11 is further configured to select to pass through the digital audio signal and block the digital ramp voltage signal according to the second control signal; optionally, the digital audio signal is obtained by a digital signal processor through mixing processing and demodulation processing; the digital-to-analog converter 11 is also used for converting a digital audio signal into an analog audio signal; the amplifying module 23 is further configured to amplify and output the analog audio signal. The voltage of the analog ramp voltage signal is smoothly increased to the first common-mode voltage, which is a dc voltage, however, the amplifying module 23 amplifies the analog audio signal to output an ac voltage, i.e., an ac sine wave is superimposed on the dc voltage.
In the present invention, the ramp signal generating module 21 generates a digital ramp voltage signal and a first control signal, wherein the voltage of the digital ramp voltage signal satisfies a predetermined functional relationship with time; the selection module 22 selects to block the digital audio signal through the digital ramp voltage signal according to the first control signal; the digital-to-analog converter 11 converts the digital ramp voltage signal into an analog ramp voltage signal; the amplifying module 23 takes a predetermined time to smoothly increase the voltage of the analog ramp voltage signal to the first common mode voltage; the ramp signal generation module 21 generates a second control signal after a predetermined time; the selection module 22 selects to pass the digital audio signal and block the digital ramp voltage signal according to the second control signal; the digital-to-analog converter 11 converts the digital audio signal into an analog audio signal; the amplifying module 23 amplifies and outputs the analog audio signal. The utility model discloses an audio circuit passes through the digital slope voltage signal that slope signal production module 21 produced, and the shape and the time of rising of the output voltage of accurate control amplifier module 23 have effectively avoided the voltage and the signal sudden change phenomenon in the audio circuit, can obviously eliminate the POP noise. Furthermore, the utility model discloses an audio circuit has still realized output voltage common mode and has established and output audio signal's difunctional multiplexing to circuit structure is simple, and the process controllability is strong.
Optionally, as shown in fig. 4, in order to illustrate a first structure of the amplifying module in the audio circuit shown in fig. 2 in the embodiment of the audio circuit of the present invention, the amplifying module 23 may include: a power amplifier 231, a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4; the power amplifier 231 is connected to the digital-to-analog converter 11, the first switch S1 is connected between the digital-to-analog converter 11 and the positive input terminal of the power amplifier 231, the second switch S2 is connected between the first common-mode voltage source 237 and the positive input terminal of the power amplifier 231, the third switch S3 is connected between the second common-mode voltage source 238 and the positive input terminal of the power amplifier 231, and the fourth switch S4 is connected between the digital-to-analog converter 11 and the negative input terminal of the power amplifier 231; the output of the power amplifier 231 is connected to the negative input of the power amplifier 231.
One of the functions of the power amplifier 231 is to amplify the analog ramp voltage signal; the first switch S1 is closed under the control of the first control signal and opened under the control of the second control signal, so that the analog ramp voltage signal is input to the power amplifier 231 from the positive input terminal of the power amplifier 231; the second switch S2 is opened under the control of the first control signal and closed under the control of the second control signal, so that the first common mode voltage is input to the power amplifier 231 from the positive input terminal of the power amplifier 231; the first common mode voltage is provided by a first common mode voltage source 237; the third switch S3 is opened under the control of the first control signal and closed under the control of the second control signal, so that the second common mode voltage is input to the power amplifier 231 from the positive input terminal of the power amplifier 231; the second common mode voltage is provided by a second common mode voltage source 238; the fourth switch S4 is opened under the control of the first control signal and closed under the control of the second control signal, so that the analog audio signal is input from the negative input terminal of the power amplifier 231 to the power amplifier 231; the second function of the power amplifier 231 is to amplify the analog audio signal; the output voltage of the power amplifier 231 is equal to the first common mode voltage, that is, the first common mode voltage is the common mode voltage of the power amplifier 231; the output voltage of the dac 11 is equal to the second common-mode voltage, which is the common-mode voltage of the dac 11. In the utility model, two common mode voltage sources are selected to be adopted, so that the numerical values of the first common mode voltage source and the second common mode voltage source are the same or different; alternatively, only one common-mode voltage source, i.e. either the first common-mode voltage source or the second common-mode voltage source, may be used, so that the common-mode voltage of the digital-to-analog converter 11 and the common-mode voltage of the power amplifier 231 are provided by the same common-mode voltage source and thus have the same value.
Optionally, referring to the schematic structural diagram shown in fig. 4 again, the amplifying module 23 may further include: a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4; the first resistor R1 is connected between the first switch S1 and the positive input terminal of the power amplifier 231; the second resistor R2 is connected between the output terminal of the power amplifier 231 and the negative input terminal of the power amplifier 231; the third resistor R3 is connected between the second common mode voltage source 238 and the third switch S3; the fourth resistor R4 is connected between the digital-to-analog converter 11 and the fourth switch S4.
The resistance value of the first resistor R1 is equal to that of the second resistor R2, and the resistance value of the third resistor R3 is equal to that of the fourth resistor R4; the ratio of the first resistor R1 to the third resistor R3 and the ratio of the second resistor R2 to the fourth resistor R4 set the gain of the analog audio signal.
Optionally, as shown in fig. 5, in order to provide a second schematic structural diagram of the amplifying module in the audio circuit shown in fig. 2 in the embodiment of the audio circuit of the present invention, the amplifying module 23 may include: a unity gain amplifier 232, a first switch S1, a second switch S2, a power amplifier 231, a third switch S3, and a fourth switch S4; the unity gain amplifier 232 is connected to the digital-to-analog converter 11, the first switch S1 is connected between the digital-to-analog converter 11 and the positive input terminal of the unity gain amplifier 232, the second switch S2 is connected between the first common mode voltage source 237 and the positive input terminal of the unity gain amplifier 232, the power amplifier 231 is connected to the digital-to-analog converter 11, the third switch S3 is connected between the second common mode voltage source 238 and the positive input terminal of the power amplifier 231, and the fourth switch S4 is connected between the digital-to-analog converter 11 and the negative input terminal of the power amplifier 231, wherein the output terminal of the unity gain amplifier 232 is connected to the negative input terminal of the unity gain amplifier 232 and the positive input terminal of the power amplifier 231, and the output terminal of the power amplifier 231 is.
The unity gain amplifier 232 is configured to amplify the analog ramp voltage signal; the first switch S1 is closed under the control of the first control signal and opened under the control of the second control signal, so that the analog ramp voltage signal is input to the unity gain amplifier 232 from the positive input terminal of the unity gain amplifier 232; the second switch S2 is opened under the control of the first control signal and closed under the control of the second control signal, so that the first common mode voltage is input to the unity gain amplifier 232 from the positive input terminal of the unity gain amplifier 232; the power amplifier 231 is used to amplify the analog audio signal; the third switch S3 is opened under the control of the first control signal and closed under the control of the second control signal, so that the second common mode voltage is input to the power amplifier 231 from the positive input terminal of the power amplifier 231; the second common mode voltage is provided by a second common mode voltage source 238; the fourth switch S4 is opened under the control of the first control signal and closed under the control of the second control signal so that the analog audio signal is input from the negative input terminal of the power amplifier 231 to the power amplifier 231.
In the present invention, the digital audio signal and the digital ramp voltage signal are converted into analog signals through the digital-to-analog converter 11 after being selected by the selection module 22. The unity gain amplifier 232 here functions as a unity gain amplifier circuit whose output voltage varies following the voltage at the positive input terminal; when the first switch S1 is turned off and the second switch S2 is turned on, the output voltage of the unity gain amplifier 232 is the first common mode voltage; when the first switch S1 is closed and the second switch S2 is open, the output voltage of the unity gain amplifier 232 is equal to the output voltage of the digital-to-analog converter 11. When the third switch S3 and the fourth switch S4 are closed, the common mode voltage of the output voltage of the power amplifier 231 is determined by the output voltage of the unit gain amplifier 232, and the analog audio signal output by the digital-to-analog converter 11 is output through the power amplifier 231. When the third switch S3 and the fourth switch S4 are turned off, the power amplifier 231 functions as a unity gain amplifier circuit, and the output voltage follows the voltage variation at its positive input terminal, that is, the output voltage variation of the unity gain amplifier 232, that is, the variation of the analog ramp voltage signal, that is, the variation of the digital ramp voltage signal. The selection module 22, in cooperation with the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4, can realize that the output voltage of the power amplifier 231 smoothly rises to the first common mode voltage first following the digital ramp voltage signal, and then amplifies the audio signal, thereby eliminating POP noise of the audio device.
Optionally, referring to the schematic structural diagram shown in fig. 5 again, the amplifying module 23 may further include: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6; the first resistor R1 is connected between the output terminal of the unity gain amplifier 232 and the positive input terminal of the power amplifier 231; the second resistor R2 is connected between the output terminal of the power amplifier 231 and the negative input terminal of the power amplifier 231; the third resistor R3 is connected between the second common mode voltage source 238 and the third switch S3; the fourth resistor R4 is connected between the digital-to-analog converter 11 and the fourth switch S4; a fifth resistor R5 is connected between the output of the unity gain amplifier 232 and the negative input of the unity gain amplifier 232; a sixth resistor R6 is connected between the negative input terminal of the unity gain amplifier 232 and the common ground terminal VSS.
The resistance value of the first resistor R1 is equal to that of the second resistor R2, and the resistance value of the third resistor R3 is equal to that of the fourth resistor R4; the ratio of the first resistor R1 to the third resistor R3 and the ratio of the second resistor R2 to the fourth resistor R4 set the gain of the analog audio signal; the ratio of the fifth resistor R5 and the sixth resistor R6 sets the gain of the analog ramp voltage signal.
As shown in fig. 6, for the structural schematic diagram of the embodiment of the audio system of the present invention, the audio system may include: the audio circuit 20, the alternating current coupling capacitor 13 and the audio playing device 14; the ac coupling capacitor 13 is connected to the audio circuit 20 and the audio playback device 14, respectively.
The audio circuit 20 includes the audio circuit shown in fig. 2, which is not described herein again; the alternating current coupling capacitor 13 is used for blocking a direct current signal in the audio signal and passing an alternating current signal in the audio signal; the audio playing device 14 is used for converting the alternating current signal into sound; the audio playback device includes a speaker.
As shown in fig. 7, which is a flow chart of an embodiment of the method for eliminating POP noise of the present invention, the method may be performed by the circuit shown in fig. 2, and the method may include the following steps:
step 71, the ramp signal generating module generates a digital ramp voltage signal and a first control signal, wherein the voltage of the digital ramp voltage signal changes along with time to meet a predetermined functional relationship;
optionally, the voltage of the digital ramp voltage signal varies with time in a linear, exponential, or logarithmic relationship.
step 73, the digital-to-analog converter converts the digital ramp voltage signal into an analog ramp voltage signal;
step 77, converting the digital audio signal into an analog audio signal by the digital-to-analog converter;
and step 78, the amplifying module amplifies and outputs the analog audio signal.
Optionally, in an example, referring to the circuit schematic shown in fig. 4, the amplifying module may include: the power amplifier is connected with the digital-to-analog converter, the first switch is connected between the digital-to-analog converter and the positive input end of the power amplifier, the second switch is connected between the first common-mode voltage source and the positive input end of the power amplifier, the third switch is connected between the second common-mode voltage source and the positive input end of the power amplifier, and the fourth switch is connected between the digital-to-analog converter and the negative input end of the power amplifier;
Optionally, the amplifying module may further include, on the basis of including the power amplifier, the first switch, the second switch, the third switch, and the fourth switch: the power amplifier comprises a first resistor, a second resistor, a third resistor and a fourth resistor, wherein the first resistor is connected between a first switch and the positive input end of the power amplifier, the second resistor is connected between the output end of the power amplifier and the negative input end of the power amplifier, the third resistor is connected between a second common-mode voltage source and a third switch, and the fourth resistor is connected between the digital-to-analog converter and a fourth switch;
the resistance value of the first resistor is equal to that of the second resistor, and the resistance value of the third resistor is equal to that of the fourth resistor; the ratio of the first resistor to the third resistor and the ratio of the second resistor to the fourth resistor set the gain of the analog audio signal.
Alternatively, in another example, referring to the circuit schematic shown in fig. 5, the amplifying module may include: the unit gain amplifier is connected with the digital-to-analog converter, the first switch is connected between the digital-to-analog converter and the positive input end of the unit gain amplifier, the second switch is connected between a first common-mode voltage source and the positive input end of the unit gain amplifier, the power amplifier is connected with the digital-to-analog converter, the third switch is connected between a second common-mode voltage source and the positive input end of the power amplifier, the fourth switch is connected between the digital-to-analog converter and the negative input end of the power amplifier, the output end of the unit gain amplifier is connected with the negative input end of the unit gain amplifier and the positive input end of the power amplifier, and the output end of the power amplifier is connected with the negative input end of the power amplifier;
Optionally, the amplifying module may further include, on the basis of including a unity gain amplifier, a first switch, a second switch, a power amplifier, a third switch, and a fourth switch: the first resistor is connected between the output end of the unity gain amplifier and the positive input end of the power amplifier, the second resistor is connected between the output end of the power amplifier and the negative input end of the power amplifier, the third resistor is connected between a second common-mode voltage source and a third switch, the fourth resistor is connected between the digital-to-analog converter and a fourth switch, the fifth resistor is connected between the output end of the unity gain amplifier and the negative input end of the unity gain amplifier, and the sixth resistor is connected between the negative input end of the unity gain amplifier and the common ground;
the resistance value of the first resistor is equal to that of the second resistor, and the resistance value of the third resistor is equal to that of the fourth resistor; the ratio of the first resistor to the third resistor and the ratio of the second resistor to the fourth resistor set the gain of the analog audio signal; the ratio of the fifth resistor to the sixth resistor sets the gain of the analog ramp voltage signal.
In the present invention, when the audio circuit works, the ramp signal generating module outputs the first control signal, and the output voltage common mode establishing process of the amplifying module, i.e. the process from step 71 to step 74, is entered; after a predetermined time, the ramp signal generating module outputs the second control signal to enter the audio signal output process, i.e., the process from step 75 to step 78. The specific process comprises the following steps: 1) the common mode establishing process of the output voltage of the amplifying module; in the process, according to a first control signal, a selection module selects a digital ramp voltage signal generated by a ramp signal generation module, the digital ramp voltage signal is converted into an analog ramp voltage signal through a digital-to-analog converter, a second switch, a third switch and a fourth switch are disconnected, a first switch is closed, an output signal of the digital-to-analog converter is sent to a positive input end of a unit gain amplifier, the output voltage of the unit gain amplifier changes along with the voltage of the positive input end of the unit gain amplifier, the output of the unit gain amplifier is connected to the positive input end of a power amplifier, the output voltage of the power amplifier changes along with the voltage of the positive input end of the power amplifier, namely the output voltage of an amplification module changes along with the shape of the digital ramp voltage; 2) an audio signal output process; in the process, according to the second control signal, the selection module selects to pass through the digital audio signal and convert the digital audio signal into an analog audio signal through the digital-to-analog converter, the second switch, the third switch and the fourth switch are closed, the first switch is opened, the output voltage of the unit gain amplifier is the first common-mode voltage, the output common-mode voltage of the power amplifier is equal to the first common-mode voltage, and the digital-to-analog converter outputs the analog audio signal and outputs the analog audio signal through the power amplifier in an inverted amplification mode. Through the process, the output voltage of the amplifying module can be accurately controlled to change along with the change of the digital ramp voltage signal, and the POP noise can be obviously eliminated. And simultaneously, the utility model discloses output voltage common mode has still been realized and has been established and output audio signal's difunctional multiplexing to circuit structure is simple, and the process controllability is strong.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present invention.
Claims (6)
1. An audio circuit, comprising:
the device comprises a ramp signal generation module, a first control module and a second control module, wherein the ramp signal generation module is used for generating a digital ramp voltage signal and a first control signal, and the change of the voltage of the digital ramp voltage signal along with time meets a preset functional relation;
the selection module is connected with the ramp signal generation module and used for selecting the digital ramp voltage signal to block the digital audio signal according to the first control signal;
the digital-to-analog converter is connected with the selection module and used for converting the digital ramp voltage signal into an analog ramp voltage signal;
the amplifying module is connected with the digital-to-analog converter and used for smoothly increasing the voltage of the analog ramp voltage signal to a first common-mode voltage in a preset time;
the ramp signal generating module is further used for generating a second control signal after the preset time;
the selection module is further used for selecting to pass through the digital audio signal and block the digital ramp voltage signal according to the second control signal;
the digital-to-analog converter is also used for converting the digital audio signal into an analog audio signal;
the amplifying module is also used for amplifying and outputting the analog audio signal.
2. The audio circuit of claim 1, wherein the amplification module comprises:
the power amplifier is connected with the digital-to-analog converter;
a first switch, connected between the digital-to-analog converter and the positive input terminal of the power amplifier, and being closed under the control of the first control signal and opened under the control of the second control signal;
a second switch connected between a first common-mode voltage source and the positive input terminal of the power amplifier, and opened under the control of the first control signal and closed under the control of the second control signal;
a third switch connected between a second common-mode voltage source and the positive input terminal of the power amplifier, and opened under the control of the first control signal and closed under the control of the second control signal;
the fourth switch is connected between the digital-to-analog converter and the negative input end of the power amplifier, is opened under the control of the first control signal and is closed under the control of the second control signal;
wherein,
and the output end of the power amplifier is connected with the negative input end of the power amplifier.
3. The audio circuit of claim 2, wherein the amplification module further comprises:
a first resistor connected between the first switch and a positive input of the power amplifier;
the second resistor is connected between the output end of the power amplifier and the negative input end of the power amplifier;
a third resistor connected between the second common mode voltage source and the third switch;
a fourth resistor connected between the digital-to-analog converter and the fourth switch;
wherein,
the resistance value of the first resistor is equal to that of the second resistor, and the resistance value of the third resistor is equal to that of the fourth resistor;
the ratio of the first resistance to the third resistance and the ratio of the second resistance to the fourth resistance set the gain of the analog audio signal.
4. The audio circuit of claim 1, wherein the amplification module comprises:
the unit gain amplifier is connected with the digital-to-analog converter and used for amplifying the analog ramp voltage signal;
a first switch connected between the digital-to-analog converter and the positive input terminal of the unity gain amplifier, and being closed under the control of the first control signal and opened under the control of the second control signal;
a second switch connected between a first common-mode voltage source and the positive input terminal of the unity gain amplifier, and opened under the control of the first control signal and closed under the control of the second control signal;
the power amplifier is connected with the digital-to-analog converter and used for amplifying the analog audio signal;
a third switch connected between a second common-mode voltage source and the positive input terminal of the power amplifier, and opened under the control of the first control signal and closed under the control of the second control signal;
the fourth switch is connected between the digital-to-analog converter and the negative input end of the power amplifier, is opened under the control of the first control signal and is closed under the control of the second control signal;
the output end of the unity gain amplifier is connected with the negative input end of the unity gain amplifier and the positive input end of the power amplifier, and the output end of the power amplifier is connected with the negative input end of the power amplifier.
5. The audio circuit of claim 4, wherein the amplification module further comprises:
a first resistor connected between the output terminal of the unity gain amplifier and the positive input terminal of the power amplifier;
the second resistor is connected between the output end of the power amplifier and the negative input end of the power amplifier;
a third resistor connected between the second common mode voltage source and the third switch;
a fourth resistor connected between the digital-to-analog converter and the fourth switch;
a fifth resistor connected between the output terminal of the unity gain amplifier and the negative input terminal of the unity gain amplifier;
a sixth resistor connected between the negative input terminal of the unity gain amplifier and a common ground;
wherein,
the resistance value of the first resistor is equal to that of the second resistor, and the resistance value of the third resistor is equal to that of the fourth resistor;
the ratio of the first resistor to the third resistor and the ratio of the second resistor to the fourth resistor set the gain of the analog audio signal;
the ratio of the fifth resistor to the sixth resistor sets the gain of the analog ramp voltage signal.
6. An audio system, comprising: audio circuit, AC coupling capacitor and audio playback device, characterized in that the audio circuit comprises the audio circuit of any of claims 1 to 5.
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| CN201320471161.XU CN203423792U (en) | 2013-08-02 | 2013-08-02 | Audio circuit and audio system |
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| CN201320471161.XU CN203423792U (en) | 2013-08-02 | 2013-08-02 | Audio circuit and audio system |
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| CN (1) | CN203423792U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103402157A (en) * | 2013-08-02 | 2013-11-20 | 北京昆腾微电子有限公司 | Audio-frequency circuit and method for eliminating POP noises |
-
2013
- 2013-08-02 CN CN201320471161.XU patent/CN203423792U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103402157A (en) * | 2013-08-02 | 2013-11-20 | 北京昆腾微电子有限公司 | Audio-frequency circuit and method for eliminating POP noises |
| CN103402157B (en) * | 2013-08-02 | 2016-09-28 | 昆腾微电子股份有限公司 | Voicefrequency circuit, audio system and the method eliminating POP noise |
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Owner name: KUNTENG MICROELECTRONIC CO., LTD. Free format text: FORMER NAME: BEIJING KUNTENG MICRO-ELECTRONICS INC. Owner name: BEIJING KUNTENG MICRO-ELECTRONICS INC. Free format text: FORMER NAME: KT MICRO, INC. |
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Address after: 100195 Haidian District, North Hollywood Road, No. 23, North Park, Central Park, building No. 4, No. Patentee after: KT MICRO, Inc. Address before: 100195 Haidian District, North Hollywood Road, No. 23, North Park, Central Park, building No. 4, No. Patentee before: Beijing Kunteng electronic Limited by Share Ltd. Address after: 100195 Haidian District, North Hollywood Road, No. 23, North Park, Central Park, building No. 4, No. Patentee after: Beijing Kunteng electronic Limited by Share Ltd. Address before: 100195 Haidian District, North Hollywood Road, No. 23, North Park, Central Park, building No. 4, No. Patentee before: KT MICRO Inc. (BEIJING) |
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