CN107809702B - Signal output circuit - Google Patents
Signal output circuit Download PDFInfo
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- CN107809702B CN107809702B CN201710940417.XA CN201710940417A CN107809702B CN 107809702 B CN107809702 B CN 107809702B CN 201710940417 A CN201710940417 A CN 201710940417A CN 107809702 B CN107809702 B CN 107809702B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2420/00—Details of connection covered by H04R, not provided for in its groups
- H04R2420/03—Connection circuits to selectively connect loudspeakers or headphones to amplifiers
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Abstract
The invention discloses a signal output circuit, which comprises an audio processing chip, an audio output circuit, a power amplifier chip, a protection circuit and a power amplifier socket which are connected in sequence, wherein the audio processing chip is used for converting and outputting an obtained audio signal; the audio output circuit is used for inputting the audio output signal output by the audio processing chip to the power amplifier chip; the power amplifier chip is connected with a biasing circuit, the biasing circuit is used for carrying out differential processing on the audio output signal input into the power amplifier chip, the power amplifier chip carries out power amplification on the audio output signal after the differential processing and then outputs the audio output signal, and the audio output signal is transmitted to a playing unit accessed by the power amplifier socket through a protection circuit so as to drive the playing unit to play the audio signal; the protection circuit is used for eliminating static electricity and surge phenomena on the playing unit and the power amplifier chip. The signal output circuit provided by the invention solves the problem that the existing audio signal is unstable when being output.
Description
Technical Field
The invention relates to the technical field of electronic circuits, in particular to a signal output circuit.
Background
With the development of the times, the living standard of people is continuously improved, the use of chips is more and more frequent, the chip refers to a silicon chip containing an integrated circuit, the size of the chip is very small, the chip is often a part of a computer or other electronic equipment, the chip is also called a microcircuit, a microchip and an integrated circuit, the variety of the chip is very wide, and in audio playing equipment, an audio processing chip and an audio power amplifier for processing audio signals and amplifying and outputting the audio signals are particularly frequently used.
At present, an audio processing chip and an audio power amplifier are often used in combination to achieve receiving and output playing of an audio signal, wherein the audio processing chip is configured to receive an input analog signal or digital signal, process the input analog signal or digital signal and convert the processed signal into a digital signal or analog signal for output, input the output signal to the audio power amplifier, amplify the signal through the audio power amplifier, and finally output the audio signal at an output end of the audio power amplifier to control sound production of a speaker.
However, in practical applications of audio playing devices, the speaker device and the audio power amplifier at the output end are often damaged due to electrostatic interference, surge, and voltage drop. In addition, during the process of turning on or off the audio power amplifier, the audio transient signal may generate strange transient noise in the speaker, so that the audio signal of the existing audio playing device is not stable enough when being output due to the influence of static electricity and other factors.
Disclosure of Invention
Based on this, the present invention provides a signal output circuit, which solves the problem of instability of the conventional audio signal output.
The invention provides a signal output circuit, which has the following specific technical scheme:
a signal output circuit comprises an audio processing chip, an audio output circuit, a power amplifier chip, a protection circuit and a power amplifier socket which are connected in sequence,
the audio processing chip is used for converting the acquired audio signals and then outputting the converted audio signals;
the audio output circuit is used for inputting the audio output signal output by the audio processing chip to the power amplifier chip;
the power amplifier chip is also connected with a biasing circuit, the biasing circuit is used for carrying out differential processing on the audio output signal input into the power amplifier chip, the power amplifier chip carries out power amplification on the audio output signal after the differential processing and then outputs the audio output signal, and the audio output signal is transmitted to a playing unit accessed by the power amplifier socket after passing through the protection circuit so as to drive the playing unit to play the audio signal;
the protection circuit is used for eliminating static electricity and surge phenomena on the playing unit and the power amplifier chip.
The signal output circuit provided by the invention can realize the input of at least one audio signal of MIC signals, differential mode audio signals and common mode audio signals through the arranged audio processing chip, and the audio signal is output after being processed and converted, the output audio output signal can filter noise waves and isolate noise in the audio output circuit, the power supply circuit and the bias circuit are provided with matched capacitors and resistors, the noise can be isolated, the noise waves can be filtered, the decoupling and the like can be eliminated, the signals input to the power amplification chip have no noise interference, the power amplification chip can isolate noise in the output audio signal after power surge due to the arrangement of the protection circuit when the signals are output, the electrostatic interference is eliminated, and when the playing unit is connected to the power amplification socket, the damage to the playing unit and the power amplification chip caused by static electricity and power is avoided, meanwhile, the audio signal can be stably output, wherein the power amplifier chip adopts a differential input and differential output mode, so that the interference of noise is inhibited, and the problem of instability in the existing audio signal output process is solved.
In addition, the signal output circuit provided by the invention can also have the following additional technical characteristics:
furthermore, the signal output circuit further comprises a control circuit and a power supply circuit, wherein the control circuit and the power supply circuit are connected with the power amplifier chip, the control circuit is used for controlling the working state of the power amplifier chip, and the power supply circuit is used for supplying power to the power amplifier chip.
The power amplifier chip can be powered and the working state of the power amplifier chip can be controlled through the control circuit and the power supply circuit, and when the power amplifier chip is required to work, the level output to the power amplifier chip through the control circuit can be converted into a high level.
Furthermore, the audio processing chip comprises an MIC signal input group pin, an audio signal input group pin, and an audio signal output group pin;
the MIC signal input group pins comprise an MIC bias pin, an MIC signal input positive pin and an MIC signal input negative pin, the MIC signal input positive pin is connected with a first capacitor, and the MIC signal input negative pin is connected with a second capacitor;
the audio signal input group pins comprise a signal positive input pin and a signal negative input pin for differential input, a signal input pin for common mode input, and a left channel input pin and a right channel input pin for left and right channel signal input;
the audio signal output group pins comprise a left channel signal output pin and a right channel signal output pin;
the audio processing chip converts the differential signal input by the MIC signal input group pin or the audio signal input by the audio signal input group pin into the audio output signal, and the audio output signal is output by the audio signal output group pin.
Through the first capacitor and the second capacitor, direct current can be isolated when MIC signals are connected to MIC signal input group pins, multiple groups of different types of audio signal input can be acquired through the set audio processing chip, acquired analog audio signals can be converted into digital audio signals when any type of audio signal input is acquired, and then audio signal output is carried out through the audio signal output group pins.
Furthermore, the power amplifier chip comprises an enable pin, a bypass pin, an audio signal input positive pin, an audio signal input negative pin, an audio amplification signal output positive pin, a power supply pin, a ground pin and an audio amplification signal output negative pin, the enable pin is connected with the control circuit, the bypass pin and the audio signal input positive pin are connected with the bias circuit, the audio signal input negative pin is connected with the audio output circuit, the power supply pin is connected with the power supply circuit, the audio amplification signal output positive pin and the audio amplification signal output negative pin are connected with the protection circuit, and the ground pin is grounded.
Further, the audio output circuit comprises a left channel audio output circuit and a right channel audio output circuit;
the left channel audio output circuit comprises a first resistor and a third capacitor which are sequentially connected with the left channel signal output pin;
the right channel audio output circuit comprises a second resistor and a fourth capacitor which are sequentially connected with the right channel signal output pin;
the other ends of the third capacitor and the fourth capacitor are connected with the audio signal input negative pin.
The audio output circuit has the advantages that the feedback and current limiting effects can be achieved in the circuit through the arranged first resistor and the second resistor, the current of the audio output circuit can be adjusted through the resistance values of the first resistor and the second resistor, and the direct current signals in the audio output circuit can be isolated through the arranged third capacitor and the fourth capacitor so as to isolate noise.
Further, the protection circuit comprises a signal output positive protection circuit and a signal output negative protection circuit;
the signal output positive protection circuit comprises a sixth resistor connected with the audio amplification signal output positive pin, a first double diode connected with the other end of the sixth resistor, a first electrostatic impedor and the power amplification socket, wherein one end of the first double diode is grounded, the other end of the first double diode is connected with the power supply pin, and the other end of the first electrostatic impedor is grounded;
the signal output negative protection circuit comprises a seventh resistor connected with the audio amplification signal output negative pin, a second double diode connected with the other end of the seventh resistor, a second electrostatic impedor and the power amplifier socket, wherein one end of the second double diode is grounded, the other end of the second double diode is connected with the power supply pin, the other end of the second electrostatic impedor is grounded, and the power amplifier socket is used for accommodating and connecting the power amplifier socket into the outside to be inserted into the playing unit.
The voltage clamping can be realized through the first double diode and the second double diode which are arranged, the voltage on the signal output positive protection circuit can be clamped between 0 and the voltage output by a power pin, the electrostatic discharge can be realized through the first electrostatic impeder and the second electrostatic impeder which are arranged, so that the electrostatic interference and the electrostatic breakdown of electronic elements are prevented, and the effect of protecting the electronic elements is realized.
Furthermore, the control circuit comprises a third resistor and a fourth resistor which are respectively connected with the enabling pin, the other end of the third resistor is grounded, the other end of the fourth resistor is connected with the control pin of the processing chip, and the power amplifier chip controls the working state of the power amplifier chip according to the level output by the control pin.
The third resistor and the fourth resistor are used in a combined mode to achieve the effect of voltage division, and the processing chip can control the working state of the power amplifier chip by controlling the level output by the control pin. When the level output by the control pin is high level, the level of the enable pin is also high level, at the moment, the power amplifier chip starts to work, and the audio signal of the audio output circuit is amplified and then transmitted to the playing unit to realize the playing of the audio. And when the level output by the control pin is low level, the power amplifier chip stops working.
Furthermore, the bias circuit comprises a fifth capacitor connected with the bypass pin, a sixth capacitor and a fifth resistor which are sequentially connected with the audio signal input positive pin, and the other ends of the fifth capacitor and the fifth resistor are grounded.
Clutter in the audio signal of filterable preceding stage input can be realized through the fifth electric capacity that sets up to the effect of current-limiting through the fifth resistance that sets up, can keep apart the effect of direct current through the sixth electric capacity that sets up, and biasing circuit and audio output circuit realize can the differential input in power amplifier chip.
Furthermore, the power supply circuit comprises a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor and a magnetic bead, which are respectively connected with the power supply pin, the other ends of the seventh capacitor, the eighth capacitor, the ninth capacitor and the tenth capacitor are grounded, and the other end of the magnetic bead is connected with a system power supply.
The magnetic bead through setting up can the filtering high frequency noise in the power, can play direct current filtering's effect through the seventh electric capacity that sets up and ninth electric capacity, can the high low frequency clutter of filtering when its cooperation is used simultaneously, and the decoupling can be realized to the combined use of eighth electric capacity and the ninth electric capacity through setting up, and it can be with getting rid of because partial circuit causes the voltage fluctuation that the power produced, avoids voltage fluctuation to make each partial circuit interfere with each other.
The signal output circuit provided by the invention can realize the input of at least one audio signal of MIC signals, differential mode audio signals and common mode audio signals through the audio processing chip, and output after processing and conversion, and the capacitor is connected before the MIC signal input group pin is connected with the MIC, the interference of direct current signals can be isolated, the noise of noise can be isolated because the capacitor and the resistor are arranged in the audio output circuit of the output audio output signal, the noise can be isolated and the noise can be isolated because the matched capacitor and the resistor are arranged in the power supply circuit and the bias circuit, the noise can be isolated, the noise and decoupling can be filtered, and the noise interference does not exist in the signals input to the power amplification chip, and the noise is isolated in the output audio signals after power amplification due to the resistor, the double diodes and the electrostatic impedor arranged in the protection circuit when the signals are output by the power amplification chip, the range of the output voltage is clamped, electrostatic interference is prevented, when the playing unit is connected to the power amplifier socket, damage to the playing unit and the power amplifier chip caused by static electricity and surge is avoided, and meanwhile, the audio signal can be stably output.
Drawings
Fig. 1 is a schematic structural diagram of a signal output circuit according to an embodiment of the present invention.
Fig. 2 is a circuit diagram of a connection portion of the signal output circuit and the audio processing chip according to an embodiment of the invention.
Fig. 3 is a schematic circuit diagram of a connection portion between a signal output circuit and a power amplifier chip according to an embodiment of the present invention.
Fig. 4 is a circuit diagram of a connection portion between a signal output circuit and a protection circuit according to an embodiment of the invention.
Fig. 5 is a circuit diagram of a power supply circuit in a signal output circuit according to an embodiment of the invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.
In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1 to 5, a signal output circuit 10 according to an embodiment of the present invention includes an audio processing chip 20, an audio output circuit 30 connected to the audio processing chip 20, a power amplifier chip 40 connected to the audio output circuit 30, a control circuit 50 connected to the power amplifier chip 40, a bias circuit 60, a power supply circuit 70, and a protection circuit 80. When the audio processing chip 20 obtains an input signal, the audio processing chip 20 converts the input signal into an audio output signal, wherein the audio output signal is amplified by the power amplifier chip 40 and then output to a playing unit for playing an audio signal, wherein the playing unit may be a speaker or a sound.
In this embodiment, the audio processing chip 20 is a CODEC chip (CODEC), which is specifically a CODEC module in a RK618 chip on the rui-core micro platform, wherein the CODEC chip is mainly responsible for converting a digital signal into an analog signal (DAC) and converting an analog signal into a digital signal (ADC), and it can be understood that in other embodiments of the present invention, the audio processing chip 20 may also be other chips, which are not described herein again. In the present embodiment, the audio processing chip 20 includes 27 pins, which at least include MIC signal input group pins, audio signal input group pins, and audio signal output group pins.
The MIC signal input group pin comprises an MIC bias pin (MICBIAS1), an MIC signal input positive pin (MIC _1P) and an MIC signal input negative pin (MIC _1N), wherein the MIC bias pin (MICBIAS1) is used for providing bias voltage for an MIC (microphone), and the MIC signal input positive pin (MIC _1P) and the MIC signal input negative pin (MIC _1N) are used for receiving differential input MIC signals. At this time, the MIC signal is input to the audio processing chip 20 in a differential input manner, and is processed by the audio processing chip 20, and then the audio signal is output through the audio signal output group pin, where it is noted that a first capacitor C1 needs to be connected before the MIC signal input positive pin (MIC _1P) is connected to the MIC signal input positive pin (MIC _1P), and the first capacitor C1 is used for isolating the effect of a direct current when the MIC signal is connected to the MIC signal input positive pin (MIC _1P), where in this embodiment, a capacitance value of the first capacitor C1 is 100 nF. As described above, the negative MIC signal input pin (MIC _1N) is connected to a second capacitor C2 before receiving the MIC signal, and the second capacitor C2 has a capacitance of 100 nF.
Further, the audio signal input group pins include a signal positive input pin (IN1P) and a signal negative input pin (IN1N) for differential input, a signal input pin (LINE) for common mode input, and a left channel input pin (IN3L) and a right channel input pin (IN3R) for left and right channel signal input. When the audio processing chip 20 obtains any type of audio signal input, the audio processing chip 20 converts the obtained analog audio signal into a digital audio signal, and then outputs the audio signal through the audio signal output group pin.
Further, the audio signal output group pins include a left channel signal output pin (LOUT) and a right channel signal output pin (ROUT), wherein the audio signal output group pins are connected to the audio output circuit 30, the audio output circuit 30 is connected to an audio signal input negative pin (IN-) of the power amplifier chip 40, wherein the audio output circuit 30 includes a left channel audio output circuit 31 and a right channel audio output circuit 32, wherein the left channel signal output pin (LOUT) is connected to the left channel audio output circuit 31, the left channel audio output circuit 31 includes a first resistor R1 and a third capacitor C3 sequentially connected to the left channel signal output pin (LOUT), and the other end of the third capacitor C3 is connected to the audio signal input negative pin (IN-) of the power amplifier chip 40. As above, the right channel signal output pin (ROUT) is connected to the right channel audio output circuit 32, the right channel audio output circuit 32 includes a second resistor R2 and a fourth capacitor C4 sequentially connected to the right channel signal output pin (ROUT), wherein the other end of the fourth capacitor C4 is connected to the audio signal input negative pin (IN-) of the power amplifier chip 40. The first resistor R1 and the second resistor R2 are used for playing a role in feedback and current limiting, and at this time, the current of the audio output circuit 30 can be adjusted by setting the resistance values of the first resistor R1 and the second resistor R2, in this embodiment, the resistance values of the first resistor R1 and the second resistor R2 are specifically 20K ohms. The third capacitor C3 and the fourth capacitor C4 are used to isolate the dc signal in the audio output circuit 30 to isolate noise.
Further, the power amplifier chip 40 is connected to the audio output circuit 30, the control circuit 50, the bias circuit 60, the power supply circuit 70 and the protection circuit 80, wherein the power amplifier chip 40 is a class D audio power amplifier, and its specific model is PT5305N, wherein the power amplifier chip 40 includes 8 pins, which are an enable pin (EN), a BYPASS pin (BYPASS), an audio signal input positive pin (IN +), an audio signal input negative pin (IN-), an audio amplified signal output positive pin (VO1), a power supply pin (VDD), a ground pin (GND) and an audio amplified signal output negative pin (VO2) IN sequence. The enable pin (EN) is connected to the control circuit 50, the control circuit 50 includes a third resistor R3 and a fourth resistor R4 connected to the enable pin (EN), respectively, further, the other end of the third resistor R3 is grounded, the other end of the fourth resistor R4 is connected to a control pin (SPK _ CON) of the processing chip, wherein the third resistor R3 and the fourth resistor R4 are combined to perform a voltage division function, in this embodiment, the resistance of the third resistor R3 is specifically 1M ohm, the resistance of the fourth resistor R4 is specifically 100K ohm, and the processing chip controls the operating state of the power amplifier chip 40 by controlling the level output from the control pin (SPK _ CON). Specifically, when the level output by the control pin (SPK _ CON) is a high level, the level of the enable pin (EN) is also a high level, and at this time, the power amplifier chip 40 starts to operate, and amplifies the audio signal of the audio output circuit 30 and transmits the amplified audio signal to the speaker to play the audio. When the level output by the control pin (SPK _ CON) is low, the level of the enable pin (EN) is also low, and at this time, the power amplifier chip 40 stops working.
Further, a BYPASS pin (BYPASS) is connected to the bias circuit 60, wherein the bias circuit 60 includes a fifth capacitor C5 connected to the BYPASS pin (BYPASS), and the other end of the fifth capacitor C5 is grounded, wherein the fifth capacitor C5 is a BYPASS capacitor for filtering noise in the audio signal input at the front stage, and wherein the capacitance value of the fifth capacitor C5 is 1 uF. Further, the audio signal input positive pin (IN +) is connected to the bias circuit 60, wherein the bias circuit 60 further includes a sixth capacitor C6 and a fifth resistor R5 sequentially connected to the audio signal input positive pin (IN +), and the other end of the fifth resistor R5 is grounded, wherein the fifth resistor R5 is used for current limiting, the sixth capacitor C6 is used for isolating direct current, IN this embodiment, the resistance of the fifth resistor R5 is specifically 1K ohm, and the capacitance of the sixth capacitor C6 is 220 nF. In the present embodiment, the differential input is implemented in the power amplifier chip 40 through the bias circuit 60 and the audio output circuit 30, and at this time, the amplified differential signal is output in the audio amplified signal output positive pin (VO1) and the audio amplified signal output negative pin (VO2) through the processing of the power amplifier chip 40.
Further, the power supply pin (VDD) is connected to the power supply circuit 70, wherein the power supply circuit 70 includes a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10 and a magnetic bead FB, which are respectively connected to the power supply pin (VDD), wherein the other ends of the seventh capacitor C7, the eighth capacitor C8, the ninth capacitor C9 and the tenth capacitor C10 are grounded, and the other end of the magnetic bead FB is connected to a system power supply (VSYS), wherein the system power supply (VSYS) provides a stable 5V power supply. The magnetic bead FB is a ferrite magnetic bead FB and is used for filtering high-frequency noise in the power supply. The resistances of the seventh capacitor C7, the eighth capacitor C8, the ninth capacitor C9 and the tenth capacitor C10 are 10uF, 100nF and 100nF respectively, the seventh capacitor C7 and the ninth capacitor C9 are combined together to perform a direct current filtering function, and simultaneously, high and low frequency noise waves can be filtered, and the eighth capacitor C8 and the ninth capacitor C9 are combined together to perform decoupling, so that voltage fluctuation caused by a part of circuits by a power supply is removed, and the voltage fluctuation is prevented from causing mutual interference of the parts of circuits. At this time, the power supply circuit 70 stably outputs the system power supply (VSYS) to the power pin (VDD) of the power amplifier chip 40, so as to provide stable 5V power supply for the power amplifier chip 40. Further, the ground pin (GND) is connected to ground.
Further, the audio amplification signal output positive pin (VO1) and the audio amplification signal output negative pin (VO2) are connected to a protection circuit 80, wherein the protection circuit 80 includes a signal output positive protection circuit 81 and a signal output negative protection circuit 82, wherein the audio amplification signal output positive pin (VO1) is connected to the signal output positive protection circuit 81, the audio amplification signal output negative pin (VO2) is connected to the signal output negative protection circuit 82, wherein the signal output positive protection circuit 81 includes a sixth resistor R6 connected to the audio amplification signal output positive pin (VO1), a first double diode D1 connected to the other end of the sixth resistor R6, a first electrostatic impedance ESD1, and a power amplifier socket 90, wherein the resistance of the sixth resistor R6 is 0 ohm, and is used for isolating noise and reducing interference. In this embodiment, the first dual diode D1 is specifically BAT54S type dual diode, and two inverse parallel diodes are packaged in the first dual diode D1, wherein an anode of one diode of the first dual diode D1 is grounded, and a cathode of the other diode is connected to a power supply pin (VDD), wherein the first dual diode D1 is used for voltage clamping, and is used for clamping the voltage on the signal output positive protection circuit 81 between 0V and 5V. The other end of the first electrostatic impeder ESD1 is grounded, in this embodiment, the first electrostatic impeder ESD1 is specifically a bidirectional zener diode, which is used for electrostatic discharge to prevent electrostatic interference and electrostatic breakdown of electronic components, so as to protect the electronic components, at this time, the first diode pair D1 and the first electrostatic impeder ESD1 arranged in the signal output positive protection circuit 81 can prevent electrostatic and surge phenomena at the power amplifier socket 90, so as to prevent damage to the speaker and the power amplifier chip 40 due to electrostatic and surge when the speaker is connected to the power amplifier socket 90.
Further, as mentioned above, the signal output negative protection circuit 82 includes a seventh resistor R7 connected to the audio amplification signal output negative pin (VO2), a second double diode D2 connected to the other end of the seventh resistor R7, a second electrostatic impeder ESD2, and a power amplifier socket 90, wherein the seventh resistor R7 has a resistance of 0 ohm, the second double diode D2 is a BAT54S type double diode, a positive pin of one diode of the second double diode D2 is grounded, and a negative electrode of the other diode is connected to the power supply pin (VDD). With the other end of the second electrostatic impeder ESD2 grounded.
Further, the power amplifier socket 90 is used for accommodating and accessing an externally inserted speaker plug, and when the speaker is accessed to the power amplifier socket 90, the audio signal amplified by the power amplifier chip 40 is transmitted to the speaker in a differential signal manner, so as to drive the speaker to play the audio signal. The power amplifier socket 90 is welded on the printed circuit board, and the first fixing pin 3 and the second fixing pin 4 of the power amplifier socket 90 are respectively fixed on the printed circuit board and connected with the ground on the printed circuit board. The power amplifier socket 90 includes two output terminals, which are connected to the speaker plug, and the two output terminals respectively obtain the audio signals inputted in the differential mode.
Wherein, when the user needs to play the power amplifier, a speaker plug is inserted into the power amplifier socket 90, the user selects the audio signal or MIC signal to be played, the audio processing chip 20 obtains the audio signal or MIC signal, the audio signal is converted and output by the audio signal output group pin, the audio signal output group pin outputs the audio signals of the left and right channels, wherein the audio signals of the left and right channels are input into the audio signal input negative pin (IN-) of the power amplifier chip 40 through the audio output circuit 30, the power amplifier chip 40 is simultaneously connected with the bias circuit 60 to the audio signal input positive pin (IN +) to form a differential signal and input into the power amplifier chip 40, the power amplifier chip 40 amplifies the power of the differential signal and outputs the amplified signal, wherein the working state of the power amplifier chip 40 is realized by the high-low state of the level of the enable pin (EN) controlled by the processing chip, when the level of the enable pin (EN) of the power amplifier chip 40 is a high level, the power amplifier chip 40 starts to operate and outputs an audio signal to the power amplifier socket 90, so as to drive a speaker connected to the power amplifier socket 90 to play the audio signal.
The signal output circuit 10 provided by the invention can realize the input of at least one audio signal of MIC signal, differential mode audio signal and common mode audio signal through the audio processing chip 20, and output after processing and conversion, and the capacitor is connected before the MIC signal input group pin is connected to the MIC, the interference of direct current signal can be isolated, the noise of noise can be isolated because the capacitor and the resistor are arranged in the audio output circuit 30, the noise can be isolated, noise and decoupling can be isolated because the matched capacitor and resistor are arranged in the power supply circuit 50 and the bias circuit 60, so that the signal input to the power amplification chip 40 has no noise interference, and the noise is isolated in the output audio signal after power amplification by the power amplification chip 40 because of the resistor, the double diode and the electrostatic impedor arranged in the protection circuit 80 when the signal is output, and the range of the output voltage is clamped and the interference of static electricity is prevented, so that when the loudspeaker is connected to the power amplifier socket 90, the damage to the loudspeaker 90 and the power amplifier chip 40 caused by static electricity and surge is avoided, meanwhile, the audio signal can be stably output, and the problem of instability in the existing audio signal output process is solved.
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, implementation may be in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (8)
1. A signal output circuit is characterized by comprising an audio processing chip, an audio output circuit, a power amplifier chip, a protection circuit and a power amplifier socket which are connected in sequence, wherein,
the audio processing chip is used for converting the acquired audio signals and then outputting the converted audio signals;
the audio output circuit is used for inputting the audio output signal output by the audio processing chip to the power amplifier chip;
the power amplifier chip is also connected with a biasing circuit, the biasing circuit is used for carrying out differential processing on the audio output signal input into the power amplifier chip, the power amplifier chip carries out power amplification on the audio output signal after the differential processing and then outputs the audio output signal, and the audio output signal is transmitted to a playing unit accessed by the power amplifier socket after passing through the protection circuit so as to drive the playing unit to play the audio signal;
the protection circuit is used for eliminating static electricity and surge phenomena on the playing unit and the power amplifier chip;
the signal output circuit further comprises a control circuit, the control circuit is used for controlling the working state of the power amplifier chip, the control circuit, the bias circuit and the audio output circuit are all electrically connected with the input end of the power amplifier chip, and the output end of the power amplifier chip is electrically connected with the protection circuit;
the control circuit comprises a third resistor and a fourth resistor which are respectively connected with the power amplifier chip, the other end of the third resistor is grounded, the other end of the fourth resistor is connected with a control pin of the power amplifier chip, and the power amplifier chip controls the working state of the power amplifier chip according to the level output by the control pin.
2. The signal output circuit of claim 1, further comprising a power supply circuit connected to the power amplifier chip, wherein the power supply circuit is configured to supply power to the power amplifier chip.
3. The signal output circuit of claim 2, wherein the audio processing chip comprises a MIC signal input group pin, an audio signal input group pin, and an audio signal output group pin;
the MIC signal input group pins comprise an MIC bias pin, an MIC signal input positive pin and an MIC signal input negative pin, the MIC signal input positive pin is connected with a first capacitor, and the MIC signal input negative pin is connected with a second capacitor;
the audio signal input group pins comprise a signal positive input pin and a signal negative input pin for differential input, a signal input pin for common mode input, and a left channel input pin and a right channel input pin for left and right channel signal input;
the audio signal output group pins comprise a left channel signal output pin and a right channel signal output pin;
the audio processing chip converts the differential signal input by the MIC signal input group pin or the audio signal input by the audio signal input group pin into the audio output signal, and the audio output signal is output by the audio signal output group pin.
4. The signal output circuit of claim 3, wherein the power amplifier chip comprises an enable pin, a bypass pin, a positive audio signal input pin, a negative audio signal input pin, a positive audio amplified signal output pin, a power supply pin, a ground pin, and a negative audio amplified signal output pin, the enable pin is connected to the control circuit, the bypass pin and the positive audio signal input pin are connected to the bias circuit, the negative audio signal input pin is connected to the audio output circuit, the power supply pin is connected to the power supply circuit, the positive audio amplified signal output pin and the negative audio amplified signal output pin are connected to the protection circuit, and the ground pin is grounded.
5. The signal output circuit of claim 4, wherein the audio output circuit comprises a left channel audio output circuit and a right channel audio output circuit;
the left channel audio output circuit comprises a first resistor and a third capacitor which are sequentially connected with the left channel signal output pin;
the right channel audio output circuit comprises a second resistor and a fourth capacitor which are sequentially connected with the right channel signal output pin;
the other ends of the third capacitor and the fourth capacitor are connected with the audio signal input negative pin.
6. The signal output circuit of claim 4, wherein the protection circuit comprises a signal output positive protection circuit and a signal output negative protection circuit;
the signal output positive protection circuit comprises a sixth resistor connected with the audio amplification signal output positive pin, a first double diode connected with the other end of the sixth resistor, a first electrostatic impedor and the power amplification socket, wherein one end of the first double diode is grounded, the other end of the first double diode is connected with the power supply pin, and the other end of the first electrostatic impedor is grounded;
the signal output negative protection circuit comprises a seventh resistor connected with the audio amplification signal output negative pin, a second double diode connected with the other end of the seventh resistor, a second electrostatic impedor and the power amplifier socket, wherein one end of the second double diode is grounded, the other end of the second double diode is connected with the power supply pin, the other end of the second electrostatic impedor is grounded, and the power amplifier socket is used for accommodating and connecting the power amplifier socket into the outside to be inserted into the playing unit.
7. The signal output circuit according to claim 4, wherein the bias circuit includes a fifth capacitor connected to the bypass pin, a sixth capacitor and a fifth resistor connected to the audio signal input positive pin in this order, and the other ends of the fifth capacitor and the fifth resistor are grounded.
8. The signal output circuit of claim 4, wherein the power supply circuit comprises a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor and a magnetic bead, which are respectively connected to the power supply pin, wherein the other ends of the seventh capacitor, the eighth capacitor, the ninth capacitor and the tenth capacitor are grounded, and the other end of the magnetic bead is connected to a system power supply.
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| CN201710940417.XA CN107809702B (en) | 2017-09-30 | 2017-09-30 | Signal output circuit |
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| CN201710940417.XA CN107809702B (en) | 2017-09-30 | 2017-09-30 | Signal output circuit |
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| CN107809702B true CN107809702B (en) | 2020-06-26 |
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| CN110324759B (en) * | 2019-06-12 | 2024-06-04 | 深圳市金锐显数码科技有限公司 | Voice sound pickup circuit and device |
| CN112153182B (en) | 2019-06-28 | 2022-04-19 | 西安中兴新软件有限责任公司 | Audio circuit and mobile terminal with same |
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