Power amplifier sensitivity switching circuit

Abstract

According to the power amplifier sensitivity switching circuit provided by the utility model, the sensitivity of an input signal is adjusted through the sensitivity switching module; a control signal of the sensitivity switching module is generated through a switching signal generator; when an input signal exceeds an amplitude range through an output signal voltage limit module, voltage limit control is carried out on the input signal; amplifying the adjusted input signal through a power amplification module; the sensitivity switching circuit can switch the sensitivity of audio input, provides fast convenience for operations such as bridging and parallel connection of the power amplifier, can suppress unstable output of the power amplifier caused by inconsistent sensitivity of the two channels while adopting the two-channel design, and has the advantages of simple structure and low cost compared with a sensitivity switching circuit composed of a pure power amplifier or a triode. By directly utilizing the mechanical characteristics of the relay, the switching sensitivity of the mechanical level is realized, and the stability and durability of the switching process are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power amplifier circuits, in particular to a power amplifier sensitivity switching circuit. Background Art

[0002] A power amplifier, commonly known as a power amplifier or amplifier, is a device used to amplify weak electrical signals from a pre-stage signal source and drive it to the post-stage speaker output to produce sound. Input sources of different sizes require different amplifier sensitivities to ensure the quality and performance of the sound. Currently common sensitivity switching circuits usually use op amps and triode devices. However, circuits constructed using op amps may increase the load resistance of the input signal, thereby reducing the gain and signal-to-noise ratio of the signal, and may also cause feedback problems, causing op amp misalignment or oscillation, thereby increasing the distortion and instability of the output signal. In contrast, the sensitivity switching circuit constructed using triodes uses a nonlinear feedback control method, which may cause the gain of the circuit to be unstable.

[0003] In summary, the problems existing in the prior art need to be solved urgently. Utility Model Content

[0004] The utility model provides a power amplifier sensitivity switching circuit, which is used to solve the defects in the prior art, realize the switching sensitivity at the mechanical level, and improve the stability and durability of the switching process.

[0005] The utility model provides a power amplifier sensitivity switching circuit, comprising:

[0006] A sensitivity switching module, wherein the sensitivity switching module is used to adjust the sensitivity of an input signal;

[0007] A switching signal generator, the switching signal generator is used to generate a control signal of the sensitivity switching module;

[0008] An output signal compression module, wherein the output signal compression module is used to apply compression control to the input signal when the input signal exceeds the amplitude range;

[0009] A power amplification module, wherein the power amplification module is used to amplify the adjusted input signal;

[0010] The switching signal generator is connected to the sensitivity switching module, the sensitivity switching module is connected to the output signal compression module, and the output signal compression module is connected to the power amplification module.

[0011] According to a power amplifier sensitivity switching circuit provided by the utility model, the sensitivity switching module includes a relay and a transistor, the switching signal generator is connected to the base of the transistor, the collector of the transistor is connected to the relay, and the emitter of the transistor is grounded.

[0012] According to a power amplifier sensitivity switching circuit provided by the utility model, the output signal voltage limiting module includes an optocoupler, a dual-channel operational amplifier and a first diode, the optocoupler is connected to the power amplifier module, the optocoupler is connected to the dual-channel operational amplifier, the anode of the first diode is connected to the dual-channel operational amplifier, and the first diode is connected to the dual-channel operational amplifier in parallel.

[0013] According to a power amplifier sensitivity switching circuit provided by the utility model, the sensitivity switching module further includes a second diode, and the second diode is connected in parallel with the relay.

[0014] According to a power amplifier sensitivity switching circuit provided by the utility model, the output signal voltage limiting module further includes a voltage dividing circuit, and the sensitivity switching module is connected to the dual-channel operational amplifier through the voltage dividing circuit.

[0015] According to a power amplifier sensitivity switching circuit provided by the utility model, an electrolytic capacitor is connected to the output end of the power amplifier module.

[0016] According to a power amplifier sensitivity switching circuit provided by the utility model, the sensitivity switching module includes a first audio input terminal and a second audio input terminal.

[0017] The power amplifier sensitivity switching circuit provided by the utility model can switch the sensitivity of audio input, and provides extremely fast convenience for bridge connection, parallel connection and other operations of the power amplifier. Moreover, while adopting a dual-channel design, it can suppress the instability of the power amplifier output caused by the inconsistent sensitivity of the dual channels. Compared with the sensitivity switching circuit composed of pure power amplifiers or triodes, it directly utilizes the mechanical characteristics of the relay to realize the switching sensitivity at the mechanical level, and improves the stability and durability of the switching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a module schematic diagram of the power amplifier sensitivity switching circuit provided by the utility model;

[0020] Figure 2 The utility model provides a circuit diagram of a power amplifier sensitivity switching circuit. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be described clearly and completely in conjunction with the drawings in the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0022] In order to solve the problems in the prior art, the utility model proposes a power amplifier sensitivity switching circuit. The power amplifier sensitivity switching circuit is described below. Figure 1 As shown, including but not limited to the following:

[0023] The utility model provides a power amplifier sensitivity switching circuit, comprising:

[0024] A sensitivity switching module, wherein the sensitivity switching module is used to adjust the sensitivity of an input signal.

[0025] The sensitivity switching module consists of relay S1, transistor Q1 and surrounding devices. The sensitivity switching signal MCU_SENSE is connected to the base of transistor Q1 through resistor R13. The collector of transistor Q1 is connected to pin 10 of relay S1, the emitter is grounded, and a resistor R14 is connected in parallel with the base. Pin 1 of relay S1 passes through one end of resistor R12, and the other end of resistor R12 is connected to a positive voltage of +15V. Pin 10 of relay S1 is connected to the anode of diode D2, and the cathode of diode D2 is connected to pin 1 of relay S1.

[0026] A switching signal generator, wherein the switching signal generator is used to generate a control signal for the sensitivity switching module.

[0027] The output signal compression module is used to apply compression control to the input signal when the input signal exceeds the amplitude range.

[0028] In order to process two signals, the output signal compression module includes an output signal compression module 1 and an output signal compression module 2. Figure 2, wherein the output signal voltage limiting module 1 includes an optocoupler U1, a dual-channel operational amplifier U57, a diode D1 and other surrounding components. After the output signal passes through the voltage divider circuit composed of resistors R4 and R3, it is connected to the 6-pin reverse input terminal of the dual-channel operational amplifier U57B. The 5-pin in-phase input terminal of the dual-channel operational amplifier U57B is grounded, and the 7-pin is connected to the anode of the diode D1. Resistors R1 and R2 are connected in series, wherein one end of R1 is connected to capacitor C2, the other end of C2 is connected to R2, the end of C2 connected to R1 is connected to the 6-pin of the dual-channel operational amplifier U57B, and the end of C2 connected to R2 is connected to the 7-pin of the dual-channel operational amplifier U57B. The cathode of the diode D1 is connected to one end of the resistor R7, and the other end of R7 is connected in series with R11 and connected to the 3-pin of the dual-channel operational amplifier U57A. One end of the capacitor C6 is grounded, and the other end is connected to the 3-pin of the dual-channel operational amplifier U57A. Pin 4 of the optocoupler U1 (the anode of the internal photodiode) is connected to pin 1 of the dual op amp U57A, pin 1 of the optocoupler U1 (the cathode of the internal photodiode) is grounded, pin 2 of the optocoupler U1 is connected to pin 6 of the op amp U25B, pin 3 of the optocoupler U1 is connected to pin 7 of the op amp U25B, and after capacitor C5 and resistor R10 are connected in parallel, one end is connected to pin 6 of the op amp U25B, and the other end is connected to pin 7 of the op amp U25B.

[0029] Similarly, the circuit principle of the output signal compression module 2 is exactly the same as that of the output signal compression module 1.

[0030] A power amplification module, wherein the power amplification module is used to amplify the adjusted input signal.

[0031] The switching signal generator is connected to the sensitivity switching module, the sensitivity switching module is connected to the output signal compression module, and the output signal compression module is connected to the power amplification module.

[0032] According to a power amplifier sensitivity switching circuit provided by the utility model, the sensitivity switching module includes a relay and a transistor, the switching signal generator is connected to the base of the transistor, the collector of the transistor is connected to the relay, and the emitter of the transistor is grounded.

[0033] According to a power amplifier sensitivity switching circuit provided by the utility model, the output signal voltage limiting module includes an optocoupler, a dual-channel operational amplifier and a first diode, the optocoupler is connected to the power amplifier module, the optocoupler is connected to the dual-channel operational amplifier, the anode of the first diode is connected to the dual-channel operational amplifier, and the first diode is connected to the dual-channel operational amplifier in parallel.

[0034] According to a power amplifier sensitivity switching circuit provided by the utility model, the sensitivity switching module further includes a second diode, and the second diode is connected in parallel with the relay.

[0035] According to a power amplifier sensitivity switching circuit provided by the utility model, the output signal voltage limiting module further includes a voltage dividing circuit, and the sensitivity switching module is connected to the dual-channel operational amplifier through the voltage dividing circuit.

[0036] According to a power amplifier sensitivity switching circuit provided by the utility model, an electrolytic capacitor is connected to the output end of the power amplifier module.

[0037] According to a power amplifier sensitivity switching circuit provided by the utility model, the sensitivity switching module includes a first audio input terminal and a second audio input terminal.

[0038] Reference Figure 2 , combined with the above embodiments, the working principle of the utility model is further explained:

[0039] In the specific circuit, after resistors R9 and R8 are connected in parallel, one end is connected to pin 3 of relay S1, and the other end is connected to resistor R5, and the input audio signal I NPUT1 is introduced. The other end of resistor R5 is connected to resistor R6, and the other end of resistor R6 is connected to pin 6 of op amp U25B, pin 5 of U25B is grounded, pin 7 of U25B is connected to the negative electrode of electrolytic capacitor C1, and the positive electrode of electrolytic capacitor C1 is connected to the output signal OUT1.

[0040] Similarly, for the second channel, after resistors R19 and R17 are connected in parallel, one end is connected to the 8th pin of relay S1, and the other end is connected to resistor R21, and the input audio signal I NPUT2 is introduced. The other end of resistor R21 is connected to resistor R22, and the other end of resistor R22 is connected to pin 3 of op amp U25A, and pin 3 of U25B is grounded. One end of capacitor C10 pulls up another group of positive voltage +15VA and connects to pin 8 of U25B, one end of capacitor C11 pulls down negative voltage -15VA and connects to pin 4 of U25B, and pin 1 of U25B is connected to the negative electrode of electrolytic capacitor C8, and the positive electrode of electrolytic capacitor C8 is connected to the output signal OUT2.

[0041] The sensitivity switching module consists of relay S1, transistor Q1 and surrounding devices. The sensitivity switching model MCU_SENSE is connected to the base of transistor Q1 through resistor R13. The collector of transistor Q1 is connected to pin 10 of relay S1, the emitter is grounded, and a resistor R14 is connected in parallel with the base. Pin 1 of relay S1 passes through one end of resistor R12, and the other end of resistor R12 is connected to a positive voltage of +15V. Pin 10 of relay S1 is connected to the anode of diode D2, and the cathode of diode D2 is connected to pin 1 of relay S1.

[0042] The output signal voltage limiting module 1 includes an optocoupler U1, a dual-channel operational amplifier U57, a diode D1, and other surrounding components. After the output signal passes through the voltage divider circuit composed of resistors R4 and R3, it is connected to the 6-pin reverse input terminal of the dual-channel operational amplifier U57B. The 5-pin non-inverting input terminal of the dual-channel operational amplifier U57B is grounded, and the 7-pin is connected to the anode of the diode D1. Resistors R1 and R2 are connected in series, wherein one end of R1 is connected to capacitor C2, the other end of C2 is connected to R2, the end of C2 connected to R1 is connected to the 6-pin of the dual-channel operational amplifier U57B, and the end of C2 connected to R2 is connected to the 7-pin of the dual-channel operational amplifier U57B. The cathode of the diode D1 is connected to one end of the resistor R7, and the other end of R7 is connected in series with R11 and connected to the 3-pin of the dual-channel operational amplifier U57A. One end of the capacitor C6 is grounded, and the other end is connected to the 3-pin of the dual-channel operational amplifier U57A. Pin 4 of the optocoupler U1 (the anode of the internal photodiode) is connected to pin 1 of the dual op amp U57A, pin 1 of the optocoupler U1 (the cathode of the internal photodiode) is grounded, pin 2 of the optocoupler U1 is connected to pin 6 of the op amp U25B, pin 3 of the optocoupler U1 is connected to pin 7 of the op amp U25B, and after capacitor C5 and resistor R10 are connected in parallel, one end is connected to pin 6 of the op amp U25B, and the other end is connected to pin 7 of the op amp U25B.

[0043] The user can switch the MCU_SENSE signal generated by the signal generator by selecting different sensitivities. When the level of the switching signal is high, the transistor Q1 is controlled to be turned on, thereby attracting the relay S1; when the level of the switching signal is low, the transistor Q1 is turned off, thereby disconnecting the relay S1. In order to accelerate the process of the transistor Q1 from being turned on to being turned off, a resistor R14 is connected in parallel with the base and the emitter. When the base voltage drops, the resistor R14 can quickly discharge the charge stored in the base. In addition, when the relay S1 is disconnected, a reverse electromotive force is generated, and a low-impedance path is provided through the reverse-connected diode D2 to protect the transistor Q1 from the impact of the reverse voltage and extend the service life of the relay contacts.

[0044] When the user selects 1V sensitivity, MCU_SENSE outputs a low level and relay S1 is disconnected. After passing through resistor R5, the input signal I NPUT1 is coupled to the negative feedback amplifier circuit and output to the power amplifier module after filtering. At the same time, after being processed by the sampling circuit and the voltage divider circuit, the current signal is detected by the optocoupler U1. When the photodiode inside the optocoupler U1 is activated, the voltage of the output signal OUT1 is pulled down and gradually returns to the normal range. The processing principle of the input signal I NPUT2 is similar to that of I NPUT1.

[0045] When the user selects 2V sensitivity, MCU_SENSE outputs a high level and closes relay S1. At this time, the input signal is divided into a suitable amplitude and input to the back-end for processing, and the above voltage limit detection is repeated.

[0046] The utility model describes a dual-channel power amplifier sensitivity switching circuit based on relays, which can adjust the sensitivity of two channels at the same time. This innovation provides a convenient way to enable the power amplifier to be bridged, paralleled, etc., thereby effectively suppressing the problem of unstable power amplifier output caused by inconsistent sensitivity of the two channels.

[0047] The design also adopts a transition buffer design to ensure the continuity and integrity of the audio signal when switching sensitivity, effectively avoiding the generation of noise and distortion, thereby improving sound quality.

[0048] Compared with pure power amplifier or triode-based sensitivity switching circuit, this design directly utilizes the mechanical characteristics of the relay to achieve mechanical sensitivity switching, improving the stability and durability of the switching process. The relay has a long life and is suitable for occasions that require long-term and frequent switching.

[0049] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A power amplifier sensitivity switching circuit, characterized in that: include: A sensitivity switching module, wherein the sensitivity switching module is used to adjust the sensitivity of an input signal; A switching signal generator, the switching signal generator is used to generate a control signal of the sensitivity switching module; An output signal compression module, wherein the output signal compression module is used to apply compression control to the input signal when the input signal exceeds the amplitude range; A power amplification module, wherein the power amplification module is used to amplify the adjusted input signal; The switching signal generator is connected to the sensitivity switching module, the sensitivity switching module is connected to the output signal compression module, and the output signal compression module is connected to the power amplification module.

2. The power amplifier sensitivity switching circuit according to claim 1, characterized in that: The sensitivity switching module comprises a relay and a transistor, the switching signal generator is connected to the base of the transistor, the collector of the transistor is connected to the relay, and the emitter of the transistor is grounded.

3. The power amplifier sensitivity switching circuit according to claim 2, characterized in that: The output signal voltage limiting module includes an optocoupler, a dual-channel operational amplifier and a first diode. The optocoupler is connected to the power amplifier module, the optocoupler is connected to the dual-channel operational amplifier, the anode of the first diode is connected to the dual-channel operational amplifier, and the first diode is connected in parallel with the dual-channel operational amplifier.

4. The power amplifier sensitivity switching circuit according to claim 2, characterized in that: The sensitivity switching module further includes a second diode connected in parallel with the relay.

5. The power amplifier sensitivity switching circuit according to claim 3, characterized in that: The output signal pressure limiting module further includes a voltage dividing circuit, and the sensitivity switching module is connected to the dual-channel operational amplifier via the voltage dividing circuit.

6. The power amplifier sensitivity switching circuit according to claim 1, characterized in that: The output end of the power amplifier module is connected to an electrolytic capacitor.

7. The power amplifier sensitivity switching circuit according to claim 1, characterized in that: The sensitivity switching module includes a first audio input terminal and a second audio input terminal.

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