Sound card and power amplifier all-in-one machine circuit

Abstract

The utility model provides a sound card and power amplifier all-in-one machine circuit, which comprises a power supply module, a sound card module and a power amplifier module, the power supply module supplies power to the sound card module and the power amplifier module, the output end of the sound card module is connected with the input end of the power amplifier module, and the power amplifier module outputs power amplifier signals to a loudspeaker unit. The sound card module is provided with more than one signal input end, the power supply module further provides a constant current source for the signal input ends, the sound card module further comprises more than one signal output end and a signal interface connected with a computer, and the sound card module can receive audio signals output from the outside. And the received audio signal is processed and is output to the power amplifier module or output to a computer end for playing. The utility model has the beneficial effects that the system application convenience is improved, the cost advantage is great, the signal processing index is good, and the performance index is obviously improved by matching the anti-interference performance of the differential input circuit.

Description

Technical Field

[0001] The utility model relates to the technical field of audio signal processing, and particularly relates to a circuit of an integrated sound card and power amplifier. Background Art

[0002] A sound card, also called an audio card, is the most basic component in multimedia technology and is a kind of hardware for realizing the mutual conversion between sound waves and digital signals. The basic function of a sound card is to convert the original sound signals from a microphone, tape, or optical disc, and output them to sound devices such as headphones, speakers, amplifiers, recorders, or to make musical instruments emit wonderful sounds through the Musical Instrument Digital Interface (MIDI).

[0003] A power amplifier, abbreviated as PA, commonly known as an "amplifier", is the most basic device in an audio system. Its task is to amplify the weak electrical signals from a signal source to drive the speakers to emit sound.

[0004] In the prior art, a sound card and a power amplifier are different devices with different functions. If the audio signals of a computer are to be played, it is necessary to configure the corresponding sound card hardware structure before the computer leaves the factory or externally plug in a sound card. In addition, a power amplifier device is required for assistance. If good sound signals are needed, additional speakers often need to be purchased. Due to the large number of devices, the procurement cost is high, the occupied space is large, and installation and debugging are also required, and the operation is cumbersome. Therefore, it is necessary to optimize the design of the existing audio processing device. Content of the Utility Model

[0005] In order to solve the problem of high noise in the prior art, the utility model provides a circuit of an integrated sound card and power amplifier.

[0006] The circuit of the integrated sound card and power amplifier of the utility model includes a power supply module, a sound card module, and a power amplifier module. Among them, the power supply module supplies power to the sound card module and the power amplifier module. The output end of the sound card module is connected to the input end of the power amplifier module, and the power amplifier module outputs a power amplifier signal to the speaker unit.

[0007] The sound card module is provided with more than one signal input end, and the power supply module also provides a constant current source for the signal input end. The sound card module also includes more than one signal output end and a signal interface connected to a computer. The sound card module can receive externally output audio signals, process the received audio signals, and output them to the power amplifier module or output them to the computer side for playback.

[0008] Furthermore, the sound card module includes a main control circuit, a DA signal conversion circuit, an AD signal conversion circuit, a first operational amplifier circuit, a second operational amplifier circuit, and a constant current source power supply circuit. Among them, the main control circuit is respectively connected to the DA signal conversion circuit and the AD signal conversion circuit. The DA signal conversion circuit is used to convert digital signals into analog signals, and output several paths of analog signals to the first operational amplifier circuit through differential or single-ended output, and then output through the signal output terminal or signal interface. The input end of the AD signal conversion circuit is connected to the output ends of several second operational amplifier circuits. The input end of the second operational amplifier circuit is connected to the signal input end. The constant current source power supply circuit provides a stable constant current source for the signal input end.

[0009] Furthermore, the main control circuit includes a processor U5, a memory U7 and a clock module respectively connected to the processor U5. The clock module is used to control the sampling rates of the DA signal conversion circuit and the AD signal conversion circuit.

[0010] Furthermore, the AD signal conversion circuit includes a signal input module and an impedance conversion module connected to the output end of the signal input module. The output end of the impedance conversion module is divided into two differential signal branches. The first differential signal branch includes a differential conversion module and a reverse differential signal amplification module provided at the output end of the differential conversion module. The second differential signal branch includes a positive-phase differential signal amplification module. The sound card power amplifier integrated circuit further includes an AD chip and a parameter setting module. The input end of the AD chip is provided with more than one group of signal input pins. One group of signal input pins is respectively connected to the output ends of the reverse differential signal amplification module and the positive-phase differential signal amplification module. The parameter setting module is used to set the parameters of the AD chip.

[0011] Furthermore, the AD chip uses a CS5381 conversion chip.

[0012] Further, the DA signal conversion circuit includes a DA conversion module, an amplification and matching module, a filtering module, an operational amplifier module, a feedback adjustment module, a protection module, and a signal output interface. Among them, the DA conversion module is used to convert digital signals into analog signals. The DA conversion module includes more than one set of first output terminals and second output terminals. The first output terminal and the second output terminal cooperate to output a pair of differential signals. The first output terminal and the second output terminal are respectively connected to two input terminals of the amplification and matching module. Two output terminals of the amplification and matching module are respectively connected to the non-inverting input terminal and the inverting input terminal of the operational amplifier module through the filtering module. The output terminal of the operational amplifier module is respectively connected to the input terminal of the feedback adjustment module and the input terminal of the protection module. The output terminal of the feedback adjustment module is connected to one of the input terminals of the operational amplifier module. The output terminal of the protection module outputs the processed single-ended analog signal to the signal output interface.

[0013] Further, the DA signal conversion circuit further includes an AC voltage division and conversion module and a first DC isolation module. The AC voltage division and conversion module and the first DC isolation module are arranged at the input terminal of the amplification and matching module.

[0014] It further includes an adjustment module and a second DC isolation module. The adjustment module is arranged between the DA conversion module and the amplification and matching module. The second DC isolation module is arranged between the output terminal of the operational amplifier module and the input terminal of the protection module.

[0015] Further, the DA conversion module includes a DA chip U101 and peripheral devices. The DA chip U101 uses a CS4398 chip. Pins 3 - 6 of the DA chip U101 are connected to the main control for receiving signals from the main control. Pin 7 of the DA chip U101 is connected to one end of a capacitor C114, the positive electrode of a polarized capacitor C113, and a 3.3V power supply. The other end of the capacitor C114 and the negative electrode of the polarized capacitor C113 are grounded. A parameter adjustment resistor is connected in series to each of pins 9 - 12 of the DA chip U101. The other ends of the parameter adjustment resistors of pins 9 and 12 are connected to the 3.3V power supply, and the other ends of the parameter adjustment resistors of pins 10 - 11 are grounded. Pin 13 is a reset pin and is connected between a series-connected resistor R113 and a capacitor C121. The other end of the resistor R113 is connected to the 3.3V power supply and pin 14, and the other end of the capacitor C121 is grounded. Pin 15 is grounded through a parallel-connected capacitor C118 and a polarized capacitor C119. A capacitor C115 and a polarized capacitor C116 are connected in parallel between pin 16 and pin 17. Among them, pin 16 and pin 21 are grounded. Pin 17 and pin 22 are connected to the 5V power supply through a bead L111. In addition, pin 22 is also grounded through a parallel-connected capacitor C111 and a polarized capacitor C112. Pins 19 and 20 are the second differential signal output terminals. Pins 23 and 24 are the second differential signal output terminals. Pin 27 is connected to the 3.3V power supply and is connected to a grounded capacitor C106. Pin 26 is grounded through a polarized capacitor C109.

[0016] Further, the constant current source power supply circuit includes a constant current source power supply chip and a selection switch. Among them, the power input terminal of the constant current source power supply chip is connected to a power supply. The power output terminal of the constant current source power supply chip is connected to pin 2 of the selection switch. Pin 1 is connected to the signal input module, and pin 3 is grounded through a resistor.

[0017] Further, the power amplifier module includes a sound card interface connected to the sound card module, a forward amplification factor setting module connected to the output terminal of the sound card interface, an amplification module connected to the output terminal of the forward amplification factor setting module, and a speaker interface with its input terminal connected to the output terminal of the amplification module and its output terminal connected to a speaker.

[0018] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0019] Integrating a sound card module and a power amplifier module, it can realize signal acquisition, processing, and power amplification output, can be compatible with the input of various signals such as a computer, has multiple outputs, and can output an audio signal for driving a speaker to generate sound. It has a high degree of integration, is easy to use, has a low cost, and does not require improvement of devices such as a computer to support the processing and output of audio signals, making it very convenient to use;

[0020] By building a high-precision DA signal conversion circuit and an AD signal conversion circuit, it has a high sampling rate, low distortion, and a high degree of audio signal restoration.

[0021] By setting up a constant current source power supply circuit in the signal input module, it can adapt to various signal output devices such as sensors that require power supply or are passive without introducing additional noise. By setting a selection switch, it can achieve compatibility of different signals in one channel. Brief Description of the Drawings

[0022] In order to more clearly illustrate the solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is a schematic diagram of one usage scenario of the sound card power amplifier integrated circuit of the present invention;

[0024] Figure 2 It is a block diagram of the structural principle of the present invention;

[0025] Figure 3 It is a block diagram of the sound card module structure of the present invention;

[0026] Figure 4 It is a block diagram of the power amplifier module structure;

[0027] Figure 5 It is a circuit schematic diagram of an embodiment of the main control circuit;

[0028] Figure 6 It is a circuit schematic diagram of an embodiment of the clock module;

[0029] Figure 7 It is a circuit schematic diagram of the AD chip and its peripheral circuits;

[0030] Figure 8 It is a circuit schematic diagram of the signal input module;

[0031] Figure 9 It is a circuit schematic diagram of the constant current source power supply circuit;

[0032] Figure 10 It is a circuit schematic diagram of the impedance conversion module and two differential signal branches;

[0033] Figure 11 It is a circuit schematic diagram of the DA chip and its peripheral circuits;

[0034] Figure 12Schematic diagram of a circuit for an embodiment of an amplification matching module, a filtering module, an operational amplifier module, a feedback adjustment module, a protection module, and a signal output interface

[0035] Figure 13 Schematic diagram of a circuit for an embodiment of a power amplifier module. Specific implementation manners

[0036] Unless otherwise defined, all technical and scientific terms used in the present utility model have the same meaning as commonly understood by those skilled in the technical field to which the present utility model belongs; the terms used in the description of the present utility model are only for the purpose of describing specific embodiments and are not intended to limit the present utility model; the terms "including" and "having" and any variations thereof in the description and claims of the present utility model and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of the present utility model or the above drawings are used to distinguish different objects and not to describe a specific order.

[0037] Referring to "embodiment" in the present utility model means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of the present utility model. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an exclusive, independent or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described in the present utility model may be combined with other embodiments.

[0038] In order to enable those skilled in the technical field to better understand the solution of the present utility model, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the drawings.

[0039] As Figure 1 shown, the sound card power amplifier integrated machine in this example can function in various scenarios. After processing various input signals in this example, it can either be output to the speaker sound generating unit to directly drive the speaker sound generating unit to generate sound, so that an additional audio system is not required, or it can be connected to a PC computer to output the processed audio signal to the PC computer and replace the sound card of the PC computer. Thus, there is no need to install an internal or external sound card device for the PC computer anymore.

[0040] As Figure 2 shown, the circuit of the sound card power amplifier integrated machine in this example includes a power supply module, a sound card module, and a power amplifier module. Among them, the power supply module supplies power to the sound card module and the power amplifier module, the output end of the sound card module is connected to the input end of the power amplifier module, and the power amplifier module outputs a power amplifier signal to the speaker unit.

[0041] The sound card module is provided with more than one signal input terminal, and the power supply module also provides a constant current source IEPE for the signal input terminal. The sound card module further includes more than one signal output terminal and a signal interface connected to a computer. The sound card module can receive an externally output audio signal, process the received audio signal, and output it to a power amplifier module or output it for playing on the computer side.

[0042] The functions of each module in this example are as follows:

[0043] Power supply module: It is powered by alternating current. Through a toroidal transformer and a rectifier circuit, it outputs the DC power signal required by the system.

[0044] Sound card module: Through the sound card system, it collects analog signals, performs high-precision AD conversion, transmits them to a dedicated SOC chip, and then transmits them to a PC computer through a USB module controller for signal acquisition and use. At the same time, it can receive data transmitted from the computer side, transmit it from the computer to the main control module through the USB control module, and then convert the digital signal into an analog signal through a high-precision DA module and output or transmit it to the power amplifier module for use.

[0045] Power amplifier module: It receives 3-way analog output signals transmitted by the sound card module, enters the power amplifier module, and amplifies the signals by 8 times through a power amplifier. At the same time, it can be converted to connect 8R / 4R speaker loads, and the maximum power can be 20W per single channel.

[0046] As Figure 3 shown, the sound card module includes a main control circuit, a DA signal conversion circuit, an AD signal conversion circuit, a first operational amplifier circuit, a second operational amplifier circuit, and a constant current source power supply circuit. Among them, the main control circuit is connected to the DA signal conversion circuit and the AD signal conversion circuit respectively through I2S and I2C buses. The DA signal conversion circuit is used to convert digital signals into analog signals, and output several paths of analog signals to the first operational amplifier circuit through differential or single-ended output, and then output them through the signal output terminal or the signal interface. The input terminal of the AD signal conversion circuit is connected to the output terminals of several second operational amplifier circuits, the input terminals of the second operational amplifier circuits are connected to the signal input terminal, and the constant current source power supply circuit provides a stable constant current source for the signal input terminal.

[0047] In this example, a total of four paths of analog input and four paths of analog output are set to meet the basic input and output requirements. Of course, more paths of input and output designs can also be supported.

[0048] As Figure 4As shown, the power amplifier module in this example includes a sound card interface connected to the sound card module, a forward amplification factor setting module connected to the output end of the sound card interface, an amplification module (mainly a power amplifier IC) connected to the output end of the forward amplification factor setting module, a speaker interface with its input end connected to the output end of the amplification module and its output end connected to the speaker. In this example, the audio signal is amplified 8 times and three power amplifier output signals for driving the speaker are output.

[0049] As Figure 5 and Figure 6 shown, the main control circuit in this example includes a processor U5, a memory U7 and a clock module respectively connected to the processor U5. The clock module is used to control the sampling rates of the DA signal conversion circuit and the AD signal conversion circuit. The clock module in this example includes a crystal oscillator X1 that provides a reference clock for the processor U5, and crystal oscillators X2 and X3 that provide reference clock signals for the channel selection and switching chip U6. By switching the channel selection and switching chip U6, the size of the chip sampling rate is controlled.

[0050] As Figures 7 - 10 shown, the AD signal conversion circuit in this example includes a signal input module and an impedance conversion module connected to the output end of the signal input module. The output end of the impedance conversion module is divided into two differential signal branches. The first differential signal branch includes a differential conversion module and an inverting differential signal amplification module provided at the output end of the differential conversion module. The second differential signal branch includes a non-inverting differential signal amplification module. The sound card power amplifier integrated circuit also includes an AD chip and a parameter setting module. The input end of the AD chip is provided with more than one set of signal input pins, and one set of signal input pins are respectively connected to the output ends of the inverting differential signal amplification module and the non-inverting differential signal amplification module. The parameter setting module is used to set the parameters of the AD chip.

[0051] By performing level conversion on the input single-ended signal through the impedance conversion module, and then processing the level-converted signal, and through inverting processing to convert it into a differential signal, in this example, by converting the single-ended signal into differential input, the anti-interference ability of the signal is improved, and the signal-to-noise ratio is improved. Through the combination of differential signals, common-mode interference can be effectively suppressed, noise can be filtered out, and the signal quality is further improved. Through the parameter setting module, parameters such as the sampling rate of the AD chip can be adjusted, and the accuracy of the entire analog-to-digital conversion circuit is improved.

[0052] The constant current source power supply circuit in this example is connected to the input end of the signal input module. By setting a constant current source power supply circuit in the signal input module, it can provide effective power supply for the free-field mic and other sensors without introducing additional noise. In addition, the utility model can adapt to various signal output devices such as sensors that require power supply or do not require a power supply. By setting a selection switch, compatibility of different signals in one channel can be achieved.

[0053] Preferably, a DC blocking module is respectively provided at the input end of the differential conversion module, the input ends of the reverse differential signal amplification module and the forward differential signal amplification module. By providing DC blocking modules at the input ends of each module in the two differential signal branches, unnecessary noise is further filtered out, thereby further improving the signal quality.

[0054] As Figures 7 - 10 shown, through the circuit design of the present invention, the accuracy of the entire circuit is further improved. This will be described in detail below in conjunction with a specific circuit.

[0055] As Figure 7 shown, the AD chip in this example preferably uses a CS5381 AD converter that supports differential input, has a high-pass filter for eliminating DC offset, a linear-phase anti-aliasing filter, and an overload detection function, can realize high-precision conversion of signals, and transmit the converted digital signals to the controller for signal acquisition and use.

[0056] The AD chip in this example can support the acquisition of two-way differential signals. Therefore, two AD chips are configured in total in this example, connected to a four-channel signal input module, and four impedance conversion modules are set for signal processing. Of course, this example also supports signal processing of 1 channel or more channels.

[0057] As Figure 8 shown, the signal input module in this example includes two input channels with the same structure. One of the input channels includes interface J301, first inductor L300, first capacitor C311, second capacitor C301, first resistor R301, and second resistor R302. Among them, the pin 2 of the first interface is grounded, the pin 1 is respectively connected to one end of the first capacitor C311 and the first inductor, the other end of the first capacitor C311 is grounded, the other end of the first inductor L300 outputs a signal through the series-connected second capacitor C301 and second resistor R302, one end of the second resistor R302 is grounded, and the other end is connected between the first resistor R301 and the signal output end.

[0058] The first capacitor C311 in this example is used for signal anti-interference, while the first inductor L300 and the first capacitor C301 are used to achieve a filtering effect, and the resistors R301 and R302 are used for current limiting and voltage limiting to achieve over-current and over-voltage protection.

[0059] As Figure 9As shown, the constant current source power supply circuit in this example also has two paths, which are respectively connected to the input ends of the signal input modules of the two paths. The first constant current source power supply circuit in this example includes a constant current source power supply chip U300 and a selection switch SW300. Among them, the power input end of the constant current source power supply chip U300 is connected to the 20M power supply, the power output end of the constant current source power supply chip U300 is connected to pin 2 of the selection switch SW300, pin 1 is connected to the signal input module, and pin 3 is grounded through a resistor.

[0060] The constant current source power supply chip U300 in this example is used to provide a constant current voltage for the signal source. Since the signal source includes devices that need to be powered and devices that do not need to be powered, such as various sensors including vibration sensors, microphones, etc., the selection switch SW300 is used to select the signal output of the devices that need to be powered or the devices that do not need to be powered.

[0061] Preferably, in this example, an indicator light D301 is also connected in series on pin 2 of the selection switch SW300 for visually obtaining the working state.

[0062] As Figure 10 shown, the number of branches of the impedance conversion module in this example is the same as the number of input channels of the signal input module. The first impedance conversion module includes an operational amplifier U303. The operational amplifier U303 includes an operational amplifier U303A. The non-inverting input pin 3 of the operational amplifier U303A is connected to the output end of the signal input module, the inverting input pin 2 is connected to the output pin 1 of the operational amplifier U303A. The negative power supply pin 4 of the operational amplifier U303A is respectively connected to the negative pole of the polarized capacitor C316, one end of the capacitor C315 and the negative power supply. The positive pole of the polarized capacitor C316 and the other end of the capacitor C315 are respectively grounded. The positive power supply pin 8 of the operational amplifier U303A is respectively connected to the positive pole of the polarized capacitor C320, one end of the capacitor C319 and the positive power supply. The negative pole of the polarized capacitor C320 and the other end of the capacitor C319 are respectively grounded.

[0063] The differential conversion module includes an operational amplifier U304. The operational amplifier U304 includes an operational amplifier U304A. The inverting input pin 2 of the operational amplifier U304A is connected to the output end of the impedance conversion module through a resistor R319 and is connected to the output pin 1 of the operational amplifier U304A through a resistor R316. The non-inverting input pin 3 of the operational amplifier U304A is connected to a reference voltage signal. The negative power supply of the operational amplifier U304A is grounded. The positive power supply pin 8 of the operational amplifier U304A is respectively connected to the positive pole of the polarized capacitor C324, one end of the capacitor C323 and the positive power supply. The negative pole of the polarized capacitor C324 and the other end of the capacitor C323 are respectively grounded.

[0064] Preferably, the number of input channels of the signal input module is an even number and is set in pairs. The second impedance conversion module shares the operational amplifier U303 with the first impedance conversion module. The operational amplifier U303 also includes the operational amplifier U303B. The second impedance conversion module uses the operational amplifier U303B. The inverting input pin 6 of the operational amplifier U303B is connected to the output pin 7 of the operational amplifier U303B. The non-inverting input pin 5 of the operational amplifier U303B is connected to the signal output end of the second signal input channel.

[0065] The differential conversion module of the second path shares the operational amplifier U304 with the differential conversion module of the first path. The operational amplifier U304 also includes the operational amplifier U304B. The second differential conversion module uses the operational amplifier U304B. The inverting input pin 6 of the operational amplifier U304B is connected to the output end of the impedance conversion module through the resistor R333 and is connected to the output pin 7 of the operational amplifier U304B through the resistor R331. The non-inverting input pin 5 of the operational amplifier U304B is connected to the reference voltage signal.

[0066] The reverse differential signal amplification module includes a follower amplifier U306A. The non-inverting input pin 3 of the follower amplifier U306A is connected to the output end of the differential conversion module. The output pin 1 of the follower amplifier U306A is connected in series with a resistor R320. The inverting input pin 2 of the follower amplifier U306A is respectively connected to one end of a resistor R315 and one end of a capacitor C314. The other end of the resistor R315 and the other end of the capacitor C314 are respectively connected to both ends of the resistor R320.

[0067] The forward differential signal amplification module includes a follower amplifier U306B. The non-inverting input pin 5 of the follower amplifier U306B is connected to the output end of the differential conversion module. The output pin 7 of the follower amplifier U306B is connected in series with a resistor R326. The inverting input pin 6 of the follower amplifier U306B is respectively connected to one end of a resistor R323 and one end of a capacitor C327. The other end of the resistor R323 and the other end of the capacitor C327 are respectively connected to both ends of the resistor R326.

[0068] In this example, the DC blocking module is a polar capacitor or a filter capacitor. The negative pole of the polar capacitor is connected to the signal input end, and the positive pole of the polar capacitor outputs the signal after DC blocking processing.

[0069] The working principle of this example is:

[0070] The input signal is converted to a suitable level through an impedance conversion module and then divided into two paths. One path is a reverse differential signal, and the other path is a positive-phase differential signal. After the reverse differential signal undergoes a DC-blocking process through the polar capacitor C317, the first-stage filtering of the signal is performed, and then it is sent to a differential conversion module for inverting signal conversion. After conversion, a DC-blocking process is performed through the polar capacitor C318, and the second-stage filtering of the signal is carried out. Then, a reference voltage conversion is performed through the resistors R317 and R322, and the output is given to the follower amplifier U306A at the subsequent stage, amplified by an appropriate multiple, and then output. The resistors R315 and the capacitor C314 are used for phase matching, and the resistors R320 and R326 arranged after the follower amplifier U306A and the follower amplifier U306B can effectively suppress oscillations.

[0071] The differential signal processed by the circuit of the present utility model finally undergoes filtering by the capacitor C325, multi-layer noise filtering, and differential processing, and then is sent to a high-precision AD chip, thereby realizing the high-precision and low-noise AD signal conversion of the present utility model. Through the cooperation of the AD chip of the present utility model and other circuits, the present utility model can achieve signal processing with a high dynamic range greater than 120 dB, low distortion, and a sampling rate as high as 192 kHz.

[0072] As Figure 11 and Figure 12 As shown, the DA signal conversion circuit of the present utility model includes a DA conversion module, an amplification and matching module, a filtering module, an operational amplifier module, a feedback adjustment module, a protection module, and a signal output interface. Among them, the DA conversion module is used to convert a digital signal into an analog signal. The DA conversion module includes more than one set of first output terminals and second output terminals. The first output terminal and the second output terminal cooperate to output a pair of differential signals. The first output terminal and the second output terminal are respectively connected to the two input terminals of the amplification and matching module. The two output terminals of the amplification and matching module are respectively connected to the non-inverting input terminal and the inverting input terminal of the operational amplifier module through the filtering module. The output terminal of the operational amplifier module is respectively connected to the input terminal of the feedback adjustment module and the input terminal of the protection module. The output terminal of the feedback adjustment module is connected to one of the input terminals of the operational amplifier module. The output terminal of the protection module outputs the processed single-ended analog signal to the signal output interface.

[0073] Through the cooperation of each module at the subsequent stage of the DA conversion module in this example, an audio signal with high indicators, low distortion, and low noise can be output. By selecting a high-precision conversion chip and building parameter-setting resistors around the high-precision conversion chip, the present utility model can set the signal reduction degree and the signal processing precision, meet the reduction degree requirements of the present utility model, and can highly restore the signal.

[0074] Preferably, as another embodiment of the present utility model, this example further includes an AC voltage division conversion module and a first DC blocking module, and the AC voltage division conversion module and the first DC blocking module are arranged at the input end of the amplification and matching module. Further, an adjustment module and a second DC blocking module are further included, the adjustment module is arranged between the DA conversion module and the amplification and matching module, and the second DC blocking module is arranged between the output end of the operational amplifier module and the input end of the protection module.

[0075] The present utility model accurately matches the amplification factor of the differential signal through the amplification and matching module, and then conveys it to the operational amplifier module for processing the conversion of the differential signal into a single-ended signal. Before processing, through triple processing of the filtering module, the first DC blocking module and the second DC blocking signal, the noise of the signal is effectively reduced. In addition, the differential signal is converted into an analog signal of one times, realizing a one-to-one restoration of the analog signal, with relatively low distortion rate and noise. In addition, through the protection module and filtering at the back end, the safety of the circuit and the quality of the output signal are improved.

[0076] As Figure 11 shown, the DA conversion module in this example includes a DA chip U101 and peripheral devices. The DA chip U101 uses a CS4398 chip. The pins 3-6 of the DA chip U101 are connected to the main control for receiving the signal of the main control. The pin 7 of the DA chip U101 is respectively connected to one end of a capacitor C114, the positive electrode of a polarized capacitor C113 and a 3.3V power supply. The other end of the capacitor C114 and the negative electrode of the polarized capacitor C113 are grounded. A parameter adjustment resistor is connected in series to each of the pins 9-12 of the DA chip U101. The other ends of the parameter adjustment resistors of pins 9 and 12 are connected to the 3.3V power supply, and the other ends of the parameter adjustment resistors of pins 10-11 are grounded. The pin 13 is a reset pin and is connected between a series-connected resistor R113 and a capacitor C121. The other end of the resistor R113 is respectively connected to the 3.3V power supply and pin 14, and the other end of the capacitor C121 is grounded. The pin 15 is grounded through a parallel-connected capacitor C118 and a polarized capacitor C119. A capacitor C115 and a polarized capacitor C116 are connected in parallel between the pin 16 and the pin 17. Among them, the pin 16 and the pin 21 are grounded. The pin 17 and the pin 22 are connected to the 5V power supply through a bead L111. In addition, the pin 22 is also grounded through a parallel-connected capacitor C111 and a polarized capacitor C112. The pins 19 and 20 are the second differential signal output ends, the pins 23 and 24 are the second differential signal output ends, the pin 27 is connected to the 3.3V power supply and is connected to a grounded capacitor C106, and the pin 26 is grounded through a polarized capacitor C109.

[0077] In this example, a high-precision DA conversion chip is selected, which can provide clear audio conversion, achieve a dynamic range of 120 dB and a total harmonic distortion plus noise of 0.0005%. In addition, the CS4398 chip supports 24-bit conversion, and the sampling frequency can be as high as 192 kHz. In addition, in this example, by setting parameter-setting resistors around the DA conversion chip and setting different resistors, different precisions and sampling rates are adapted, so that the entire circuit of the present utility model can be better adapted.

[0078] As Figure 12 shown, the DA conversion chip in this example can output two groups of differential signals. Therefore, in this example, two signal processing branches are built to process the two groups of differential signals output by the DA conversion chip. A total of two DA conversion chips are required for the four processing branches in this example.

[0079] The structures of the first signal processing branch and the second signal processing branch are the same. In this example, one of the branches is used to illustrate the present utility model in detail.

[0080] The adjustment module in this example includes two resistors R118 and R112 connected in series on the differential line, which are used for impedance matching at the signal input end. The resistance value is adjusted according to the actual situation.

[0081] The amplification and matching module in this example includes a first resistor R119, a second resistor R120, a third resistor R123, and a fourth resistor R124. Among them, the first resistor R119 and the second resistor R120 are connected in series on the first differential signal line, and the third resistor R123 and the fourth resistor R124 are connected in series on the second differential signal line. It is used to set the amplification factor of the subsequent operational amplifier module. In this example, through operational amplifier processing, the differential signal is converted into an analog signal with a factor of 1, so as to achieve equal-proportion restoration of the signal.

[0082] Similarly, the filtering module in this example includes two branches. The output end of the first branch is connected between the first resistor and the second resistor, and the output end of the second branch is connected between the third resistor and the fourth resistor. The filtering module in this example is filtering capacitors C117 and C128, and the circuit is simple and effective. Of course, in this example, it can also be set as multiple parallel capacitors, or a Π-type filter and other structures.

[0083] The AC voltage dividing and converting module in this example is arranged at the output end of the filtering module. The AC voltage dividing and converting module includes more than one resistor R127 and R128 connected in series. The first DC blocking module uses a first polar capacitor C129. One end of the series-connected resistors R127 and R128 is connected to the input end of the amplification and matching module, and the other end is connected to the positive electrode of the first polar capacitor C129. The negative electrode of the first polar capacitor C129 is grounded. Through the filtering module, AC voltage division, and then through the processing of the first DC blocking module, the DC can be isolated, the AC signal can be converted into a suitable signal intensity, sent to the operational amplifier module, the noise can be reduced, and the signal accuracy at the input end of the operational amplifier module can be improved. In addition, in this example, a polar capacitor C124 is also arranged at the output end of the operational amplifier module as the second DC blocking module to further isolate the DC signal from the signal.

[0084] The operational amplifier module in this example uses an operational amplifier U100. The operational amplifier U100 includes operational amplifiers U100A and U100B. The first signal processing branch and the second signal processing branch in this example share an operational amplifier. Among them, the first signal processing branch uses operational amplifier U100A, and the second signal processing branch uses operational amplifier U100B. The feedback adjustment module includes a fifth resistor R112 and a first capacitor C120. One end of the fifth resistor R112 and the first capacitor C120 is connected to the output end of the operational amplifier module U100B. The other end of the fifth resistor R112 is connected between the first resistor R119 and the second resistor R120. The first capacitor C120 is connected to the output end of the second resistor R112. The first capacitor C120 in this example is used to adjust the phase of the operational amplifier U100B and suppress high-frequency oscillation. The second resistor R112 in this example serves as a feedback resistor and cooperates with the previous-stage amplification and matching resistor to enable the operational amplifier U100B to control the output of a reasonable amplification factor.

[0085] As Figure 12 shown, the protection module in this example includes an overcurrent protection unit, an interference suppression unit, and a filtering unit. Among them, the overcurrent protection unit is used to perform overcurrent protection on the circuit. The interference suppression unit is used to suppress high-frequency noise, spike interference, and electromagnetic interference on the signal line. The filtering unit is used to filter the signal. The overcurrent protection unit in this example can use devices such as resistors and switching tubes. The interference suppression unit in this example uses a magnetic bead L102 and can also use devices such as electrostatic tubes. The filtering unit in this example uses a filtering capacitor C105. After the output signal is processed by the protection module in this example, a highly restored analog signal is output to the output interface J101.

[0086] Compared with the prior art, the utility model selects a high-precision processing chip and builds a signal processing circuit at the rear stage. Although simple resistors, capacitors, etc. are used for building, the structure is simple and reliable, the cost is low, and various indicators such as the noise, distortion degree, and signal-to-noise ratio of the signal are good, meeting the decoding requirements of various audio signals.

[0087] As Figure 13 shown, in this example, a total of 4 power amplifier modules with the same structure are set up, which are respectively used to connect four speakers to achieve a stereo effect. Taking one of the channels as an example for illustration, J101 in this example is a sound card interface connected to the sound card module and is used to connect to the sound card output interface. The speaker interface J106 in this example is used to connect to the speaker unit. The interface J105 is used to connect to the input signal and can be compatible with the signals of other models.

[0088] The amplification module in this example uses a low-distortion audio amplifier LM1875 and is powered by dual power supplies. It can achieve 8-fold signal amplification, with a speaker load of 8R / 4R, and the maximum power can be 20W for a single channel.

[0089] In this example, the amplification multiple of the instrumentation amplifier U101 is determined by the ratio of the resistor R324 and the resistor 104. After the signal is amplified, through filtering and other processing by resistor-capacitor components, it is output to the speaker through the speaker interface J106 to make the speaker emit sound.

[0090] From the above solution, it can be seen that the utility model integrates a sound card module and a power amplifier module, can realize signal acquisition, processing, and power amplification output, can be compatible with the input of various signals such as a computer, has multiple outputs, and can output audio signals for driving speakers to generate sound. It has high integration, is convenient to use, has a low cost, and does not require improvement of devices such as a computer to support the processing and output of audio signals, making it very convenient to use.

[0091] Aiming at the problem that the prior art cannot meet the test requirements of high-precision signals, the utility model adopts high-standard AD and DA modules, and builds a high-precision DA signal conversion circuit and an AD signal conversion circuit. It has a high sampling rate, low distortion degree, and a high degree of audio signal restoration. Indicators such as the signal-to-noise ratio, distortion, and dynamic range are all good. With the anti-interference performance of the differential input circuit, the performance indicators are significantly improved. In the market, a sound card and a power amplifier are usually two separate devices, while the utility model combines the power amplifier and the sound card into a complete system, improving the convenience of system application and having a large cost advantage. At the same time, an IEPE power supply is integrated internally, increasing the high integration of the system.

[0092] The above-mentioned specific implementation manners are the preferred implementation manners of the utility model, and do not limit the specific implementation scope of the utility model. The scope of the utility model includes but is not limited to this specific implementation manner. All equivalent changes made in accordance with the utility model are within the protection scope of the utility model.

Claims

1. A circuit of a sound card power amplifier integrated machine, characterized in that: It includes a power supply module, a sound card module and a power amplifier module. Among them, the power supply module supplies power to the sound card module and the power amplifier module. The output end of the sound card module is connected to the input end of the power amplifier module. The power amplifier module outputs a power amplifier signal to the speaker unit. The sound card module is provided with more than one signal input end. Moreover, the power supply module also provides a constant current source for the signal input end. The sound card module further includes more than one signal output end and a signal interface connected to a computer. The sound card module can receive an externally output audio signal, process the received audio signal, and output it to the power amplifier module or output it for playing on the computer side.

2. The integrated circuit of sound card power amplifier according to claim 1, characterized in that: The sound card module includes a main control circuit, a DA signal conversion circuit, an AD signal conversion circuit, a first operational amplifier circuit, a second operational amplifier circuit, and a constant current source power supply circuit. Among them, the main control circuit is respectively connected to the DA signal conversion circuit and the AD signal conversion circuit. The DA signal conversion circuit is used to convert a digital signal into an analog signal, and output several paths of analog signals to the first operational amplifier circuit through differential or single-ended output, and then output through the signal output end or the signal interface. The input end of the AD signal conversion circuit is connected to the output ends of several second operational amplifier circuits. The input end of the second operational amplifier circuit is connected to the signal input end. The constant current source power supply circuit provides a stable constant current source for the signal input end.

3. The integrated circuit of sound card and power amplifier according to claim 2, characterized in that: The main control circuit includes a processor U5, a memory U7 and a clock module respectively connected to the processor U5. The clock module is used to control the sampling rate of the DA signal conversion circuit and the AD signal conversion circuit.

4. The integrated circuit of sound card and power amplifier according to claim 2, wherein: The AD signal conversion circuit includes a signal input module, an impedance conversion module connected to the output end of the signal input module. The output end of the impedance conversion module is divided into two differential signal branches. The first differential signal branch includes a differential conversion module and an inverting differential signal amplification module provided at the output end of the differential conversion module. The second differential signal branch includes a non-inverting differential signal amplification module. The sound card power amplifier integrated circuit further includes an AD chip and a parameter setting module. The input end of the AD chip is provided with more than one group of signal input pins. One group of signal input pins is respectively connected to the output ends of the inverting differential signal amplification module and the non-inverting differential signal amplification module. The parameter setting module is used to set the parameters of the AD chip.

5. The integrated circuit of sound card and power amplifier according to claim 4, characterized in that: The AD chip adopts a CS5381 conversion chip.

6. The integrated sound card power amplifier circuit according to claim 2, wherein: The DA signal conversion circuit includes a DA conversion module, an amplification and matching module, a filtering module, an operational amplifier module, a feedback adjustment module, a protection module, and a signal output interface. Among them, the DA conversion module is used to convert digital signals into analog signals. The DA conversion module includes more than one set of first output terminals and second output terminals. The first output terminals and the second output terminals cooperate to output a pair of differential signals. The first output terminals and the second output terminals are respectively connected to two input terminals of the amplification and matching module. Two output terminals of the amplification and matching module are respectively connected to the non-inverting input terminal and the inverting input terminal of the operational amplifier module through the filtering module. The output terminal of the operational amplifier module is respectively connected to the input terminal of the feedback adjustment module and the input terminal of the protection module. The output terminal of the feedback adjustment module is connected to one of the input terminals of the operational amplifier module. The output terminal of the protection module outputs the processed single-ended analog signal to the signal output interface.

7. The integrated circuit of sound card and power amplifier according to claim 6, wherein: The DA signal conversion circuit further includes an AC voltage division and conversion module and a first DC blocking module. The AC voltage division and conversion module and the first DC blocking module are arranged at the input terminal of the amplification and matching module. It further includes an adjustment module and a second DC blocking module. The adjustment module is arranged between the DA conversion module and the amplification and matching module. The second DC blocking module is arranged between the output terminal of the operational amplifier module and the input terminal of the protection module.

8. The integrated circuit of sound card and power amplifier according to claim 6, characterized in that: The DA conversion module includes a DA chip U101 and peripheral devices. The DA chip U101 uses a CS4398 chip. Pins 3-6 of the DA chip U101 are connected to the main control for receiving signals from the main control. Pin 7 of the DA chip U101 is respectively connected to one end of a capacitor C114, the positive electrode of a polarized capacitor C113, and a 3.3V power supply. The other end of the capacitor C114 and the negative electrode of the polarized capacitor C113 are grounded. A parameter adjustment resistor is connected in series to each of pins 9-12 of the DA chip U101. The other ends of the parameter adjustment resistors of pins 9 and 12 are connected to the 3.3V power supply. The other ends of the parameter adjustment resistors of pins 10-11 are grounded. Pin 13 is a reset pin and is connected between a series-connected resistor R113 and a capacitor C121. The other end of the resistor R113 is respectively connected to the 3.3V power supply and pin 14. The other end of the capacitor C121 is grounded. Pin 15 is grounded through a parallel-connected capacitor C118 and a polarized capacitor C119. A capacitor C115 and a polarized capacitor C116 are connected in parallel between pin 16 and pin 17. Among them, pins 16 and 21 are grounded. Pins 17 and 22 are connected to the 5V power supply through a bead L111. In addition, pin 22 is also grounded through a parallel-connected capacitor C111 and a polarized capacitor C112. Pins 19 and 20 are the second differential signal output terminals. Pins 23 and 24 are the second differential signal output terminals. Pin 27 is connected to the 3.3V power supply and is connected to a grounded capacitor C106. Pin 26 is grounded through a polarized capacitor C109.

9. The integrated circuit of the sound card power amplifier according to claim 2, wherein: The constant current source power supply circuit includes a constant current source power supply chip and a selection switch. Among them, the power input terminal of the constant current source power supply chip is connected to a power supply, the power output terminal of the constant current source power supply chip is connected to pin 2 of the selection switch, pin 1 is connected to a signal input module, and pin 3 is grounded through a resistor.

10. The integrated circuit of sound card power amplifier according to claim 1, characterized in that: The power amplifier module includes a sound card interface connected to the sound card module, a forward amplification factor setting module connected to the output terminal of the sound card interface, an amplification module connected to the output terminal of the forward amplification factor setting module, a speaker interface with its input terminal connected to the output terminal of the amplification module and its output terminal connected to a speaker.

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