Sound-controlled full-time amplitude-domain bias full-link lossless class-A audio power amplifier

Abstract

The invention discloses a sound control type full-time amplitude domain bias full-link lossless class-A audio power amplifier. Firstly, static consumption reduction is realized by setting a static current (400-600mA); secondly, by adopting an innovative full-time amplitude domain pulse-by-pulse bias scheme and adopting a pulse widening technology, accurate tracking of an audio signal by an ultra 360-degree dynamic bias signal is realized, and dynamic consumption reduction is realized to the greatest extent; thirdly, the audio signal and the power amplifier tube are isolated by the over 360-degree dynamic bias signal like the same isolation field, so that the audio signal is suspended in the internal space of the power amplifier tube, the possibility of deformation caused by direct contact between the audio signal and the tube wall of the power amplifier tube is avoided, and switching distortion, transient distortion and the like are dynamically eliminated; frequency domain transformation and multi-stage processing do not need to be carried out on the audio signals, time delay is reduced, the possibility of signal distortion is reduced, and reliable technical guarantee is provided for high-fidelity and low-power-consumption amplification of a novel A-type power amplifier.

Description

Technical Field

[0001] This invention belongs to the field of audio power amplification technology, specifically relating to a volume-controlled, full-time amplitude-domain biased, lossless Class A audio power amplifier. Background Technology

[0002] As is well known, Class A amplifiers have the best linearity because their two power transistors remain on throughout the entire signal amplification cycle, enabling them to reproduce the original quality of music with high fidelity. They are the best linear amplifiers. However, Class A amplifiers are large, heavy, and expensive, and their high power consumption is a fatal flaw. For nearly a century, much research has focused on how to improve the efficiency of Class A amplifiers by reducing power consumption while further improving their quality. Among these, domestic and international research and patent literature have proposed many technical solutions based on "dynamic bias circuits," "non-cutoff bias circuits," "real-time bias circuits," and "sliding bias circuits," and some products have even been launched. These solutions have all reduced the power consumption and improved the quality of Class A amplifiers to some extent, but they generally suffer from limited improvement and low control precision.

[0003] Among them, the latest domestic patent proposes a method for advance servo biasing of a Class A audio power amplifier and the amplifier itself. The core idea is to split the input audio signal into two paths: one path undergoes ADC conversion, delay, and then DAC conversion, serving as the audio input signal to the power amplifier for amplification and output; the other path, with no delay, serves as the advance servo bias control signal, ultimately controlling the quiescent current of the power amplifier transistor to change with the amplitude of the audio input signal, thereby achieving power reduction. This scheme may have high control precision and real-time performance, and the power reduction effect may be significant. However, the circuitry is relatively complex, and its biggest drawback is that it "invites the wolf into the house" by subjecting the original audio input signal to multiple... The multiple transformation delays and other processing introduce a significant amount of "artificial noise," which is akin to "robbing Peter to pay Paul." In today's world where people pursue high-quality music playback, this technical solution is somewhat counterproductive. Furthermore, when Class A amplifiers operate at high dynamic levels, the audio signal directly drives the amplifier tubes, causing them to hit the tube walls and resulting in signal deformation. This leads to various nonlinear distortions (such as switching distortion and transient distortion). Therefore, given these shortcomings, providing a lossless Class A audio amplifier with full-time amplitude-domain bias and volume control that reduces power consumption and effectively addresses various nonlinear distortions has become an urgent problem to solve. Summary of the Invention

[0004] The purpose of this invention is to provide a volume-controlled, full-time amplitude-domain biased, lossless Class A audio power amplifier to solve the problems of signal delay and distortion, and high power consumption caused by multiple transformations of the original audio signal in the prior art. This invention aims to fully leverage the inherent advantages of Class A audio power amplifiers and minimize various types of distortion and power consumption in the system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: Firstly, a volume-controlled, full-time amplitude-domain biased, end-to-end lossless Class A audio power amplifier is provided, including: A lossless and biased audio processing circuit, wherein the input terminal of the lossless and biased audio processing circuit is connected to the original audio signal, and is used to perform Class A follower current amplification processing on the original audio signal to obtain a first lossless audio signal output to a differential amplifier circuit, and is used to generate a biased audio signal based on the original audio signal and output it to an opto-bridge isolation circuit. The differential amplifier circuit is used to differentially amplify the first lossless audio signal to obtain the second lossless audio signal, and then amplify the second lossless audio signal through the voltage amplifier circuit and output it to the base of the power amplifier driver transistor. The opto-bridge isolation circuit is used to opto-isolate the bias audio signal to obtain a delayed audio signal, and output the delayed audio signal to the full-time amplitude domain pulse-by-pulse bias circuit. A full-time amplitude domain pulse-by-pulse bias circuit is used to generate a first dynamic bias signal with a phase angle greater than 180° during the positive half-cycle of a third lossless audio signal, and a second dynamic bias signal with a phase angle greater than 180° during the negative half-cycle, based on a delayed audio signal. The two dynamic bias signals are output to the base of a power amplifier driver transistor. The collector of the power amplifier driver transistor is electrically connected to a power supply, and the emitter of the power amplifier driver transistor is electrically connected to the power amplifier transistor. The third lossless audio signal is an audio signal generated by voltage amplification of the second lossless audio signal.

[0006] Based on the above disclosure, this invention first uses a lossless and bias audio processing circuit to perform Class A follower current amplification on the original audio signal to obtain a first lossless audio signal, and simultaneously outputs a bias audio signal to the opto-bridge isolation circuit. Then, a differential amplifier circuit is used to differentially amplify the first lossless audio signal, and a voltage amplifier circuit is used to voltage amplify the differentially amplified audio signal to obtain a third lossless audio signal, which is output to the base of the power amplifier driver transistor. At the same time, the bias audio signal enters the opto-bridge isolation circuit for opto-isolation processing, becoming a delayed audio signal with the same waveform as the bias audio signal (very low distortion), but floating (not common ground) and single-ended output. Then, the full-time amplitude domain pulse-by-pulse bias circuit generates a leading and lagging dynamic bias signal with a phase angle greater than 180° in the positive and negative half-cycles of the third lossless audio signal, respectively, based on the delayed audio signal, and finally outputs it to the base of the power amplifier driver transistor, thereby combining with the third lossless audio signal to drive the power amplifier driver transistor.

[0007] Based on this, since the phase angle of the dynamic bias signal is greater than 180°, the aforementioned dynamic bias signal can achieve full-time amplitude domain coverage of the third lossless audio signal, that is, the bias signal envelops the entire third lossless audio signal. Thus, when driving the power amplifier's driver transistor, during the rising phase of the audio signal (i.e., the rising edge of the signal), the rising edge of the dynamic bias signal will pass first, followed by the rising edge of the third lossless audio signal; similarly, during the falling phase of the audio signal, the falling edge of the third lossless audio signal will pass first (because the bias signal covers the audio signal), followed by the falling edge of the dynamic bias signal. Therefore, within one signal cycle, This system enables the bias signal to be activated before the audio signal during the rising phase of the audio signal, and the audio signal to be deactivated before the bias signal during the falling phase of the audio signal. Based on this, the dynamic bias signal acts as an "isolation field," causing the original audio signal to "suspend" in the "internal space" of the power amplifier tube. This avoids the possibility of "deformation" caused by direct "physical" contact between the original audio signal and the "tube wall" of the power amplifier tube. This maximizes the reliability of the power amplifier system in Class A mode under complex conditions with a wide frequency range and large dynamic range, thereby dynamically eliminating various nonlinear distortion problems such as switching distortion and transient distortion.

[0008] Meanwhile, pulse broadening technology is used to achieve precise pre-tracking control of the original audio signal by the dynamic bias signal, thereby maximizing the dynamic and precise power consumption reduction of the system. The dynamic bias signal is generated based on the delayed audio signal, which is generated by isolating the original audio signal through an opto-bridge. Therefore, when the original audio signal changes, the dynamic bias signal also changes accordingly. That is, the dynamic bias signal can accurately follow the changes of the original audio signal (i.e., its amplitude is positively correlated with the original audio signal). In this way, the magnitude of the dynamic bias signal can be dynamically adjusted according to the amplitude of the audio signal, thereby achieving the purpose of dynamically reducing power consumption. In addition, since this invention does not require frequency domain processing such as transformation of the original audio signal, it preserves the original appearance of the original audio signal to the greatest extent, thus fundamentally ensuring the quality of the output audio.

[0009] Through the above design, this invention employs an innovative full-time amplitude domain pulse-by-pulse biasing scheme to achieve a 360° floating full-time amplitude domain wrapping of the original audio signal by the dynamic bias signal. In this way, on the one hand, pulse broadening technology enables precise pre-tracking control of the original audio signal by the dynamic bias signal, thereby maximizing the system's dynamic and precise power reduction; on the other hand, it allows for the function of activating the bias signal before the audio signal in the rising phase of the audio signal, and terminating the audio signal before the bias signal in the falling phase of the audio signal. Based on this, the original audio signal can be avoided... Because of the direct physical contact between the amplifier tube and the tube wall, deformation can occur, thereby dynamically eliminating various nonlinear distortion problems such as switching distortion and transient distortion. In addition, this invention does not require frequency domain processing such as transformation of the original audio signal, thus preserving the original audio signal to the greatest extent and further ensuring the quality of the output audio. Therefore, this invention effectively solves the long-standing contradiction between power consumption and the pursuit of high-quality music effects in Class A audio amplifiers, effectively improving the energy efficiency of the amplifier system while ensuring excellent audio performance.

[0010] In one possible design, the lossless and biased audio processing circuit includes: a first operational amplifier and a second operational amplifier; The non-inverting input of the second operational amplifier is electrically connected to the adjustment terminal of the potentiometer. One end of the potentiometer is electrically connected to an audio interface for receiving the original audio signal through a first resistor. The output terminal of the second operational amplifier is connected to the inverting input terminal. The output terminal of the second operational amplifier outputs the first lossless audio signal, and the other end of the potentiometer is grounded. The inverting input of the first operational amplifier is electrically connected to the non-inverting input of the second operational amplifier. The non-inverting input of the first operational amplifier is grounded. The output of the first operational amplifier is connected to the inverting input, and the output of the first operational amplifier outputs the bias audio signal.

[0011] In one possible design, the differential amplifier circuit includes: a first transistor, a second transistor, a third transistor, and a fourth transistor; The bases of the first transistor and the second transistor are both electrically connected to the first output terminal of the lossless and biased audio processing circuit. The collectors of the first transistor and the third transistor are electrically connected to the positive terminal of the power supply, and the collectors of the second transistor and the fourth transistor are electrically connected to the negative terminal of the power supply. The first output terminal is used to output the first lossless audio signal. The emitters of the first transistor and the third transistor are both electrically connected to the negative terminal of the power supply through a second resistor, and the emitters of the second transistor and the fourth transistor are both electrically connected to the positive terminal of the power supply through a third resistor. The base of the third transistor and the base of the fourth transistor are electrically connected to one end of the fourth resistor, wherein the other end of the fourth resistor is grounded through the first electrolytic capacitor. The base of the fourth transistor is also electrically connected to the output terminal of the power amplifier transistor through the fifth resistor. The collectors of the first transistor and the collectors of the second transistor serve as the output terminals of the differential amplifier circuit, outputting the second lossless audio signal.

[0012] In one possible design, the voltage amplifier circuit includes: a fifth transistor and a sixth transistor; The base of the fifth transistor is electrically connected to the collector of the first transistor, and the base of the sixth transistor is electrically connected to the collector of the second transistor. The emitter of the fifth transistor is electrically connected to one end of the first inductor through the sixth resistor, and the other end of the first inductor is electrically connected to the positive terminal of the power supply. The emitter of the sixth transistor is electrically connected to one end of the second inductor through the seventh resistor, wherein the other end of the second inductor is electrically connected to the negative terminal of the power supply; The collectors of the fifth transistor and the sixth transistor serve as the output terminals of the voltage amplifier circuit, outputting a third lossless audio signal to the base of the power amplifier driver transistor.

[0013] In one possible design, a full-time amplitude domain pulse-by-pulse bias circuit is used to receive an externally input static bias signal; The full-time amplitude domain pulse-by-pulse bias circuit is also used to generate a first comprehensive bias signal based on the static bias signal and the first dynamic bias signal, and to generate a second comprehensive bias signal based on the static bias signal and the second dynamic bias signal, and output the first comprehensive bias signal and the second comprehensive bias signal to the base of the power amplifier driver transistor.

[0014] In one possible design, the full-time amplitude domain pulse-by-pulse bias circuit includes: a reference source, a positive pulse broadening circuit, a negative pulse broadening circuit, a detection and delay circuit, a first electronic switch, a second electronic switch, a subtractor, and an adder. The reference source is electrically connected to the input terminals of the positive pulse broadening circuit and the negative pulse broadening circuit, respectively, to provide a reference voltage to the positive pulse broadening circuit and the negative pulse broadening circuit; The input terminal of the positive pulse broadening circuit is also electrically connected to the output terminal of the opto-bridge isolation circuit, which is used to generate a half-wave audio signal with a negative half-cycle greater than 180° as a second dynamic bias signal based on the delayed audio signal and the reference voltage, and output it to the first electronic switch. The input terminal of the negative pulse broadening circuit is also electrically connected to the output terminal of the opto-bridge isolation circuit, which is used to generate a half-wave audio signal with a positive half-cycle greater than 180° as a first dynamic bias signal based on the delayed audio signal and the reference voltage, and output it to the second electronic switch. The input terminal of the detection and delay circuit is electrically connected to the output terminal of the opto-bridge isolation circuit. The output terminal of the detection and delay circuit is electrically connected to the first electronic switch and the second electronic switch, respectively. The first electronic switch is electrically connected to the subtractor, and the second electronic switch is electrically connected to the adder. Both the subtractor and the adder are electrically connected to a static bias signal generation circuit to receive the static bias signal output by the static bias signal generation circuit. The subtractor generates a second combined bias signal based on the static bias signal and the second dynamic bias signal, and outputs it to the base of the power amplifier driver transistor. The adder generates a first combined bias signal based on the static bias signal and the first dynamic bias signal, and outputs it to the base of the power amplifier driver transistor.

[0015] In one possible design, a detection and delay circuit is used to simultaneously output a high-level signal for a preset duration to the first electronic switch and the second electronic switch when the delayed audio signal is detected to be output by the opto-bridge isolation circuit, so as to turn on the first electronic switch and the second electronic switch; and when the delayed audio signal is detected to disappear, after a preset delay, simultaneously output a low-level signal to the first electronic switch and the second electronic switch to turn off the first electronic switch and the second electronic switch.

[0016] In one possible design, the power amplifier driver transistors include: a first driver transistor and a second driver transistor; The base of the first driving transistor is electrically connected to the output terminal of the subtractor and the output terminal of the voltage amplifier circuit, respectively. The base of the second driving transistor is electrically connected to the output terminal of the adder and the output terminal of the voltage amplifier circuit, respectively. The collector of the first driving transistor is electrically connected to the positive terminal of the power supply, the collector of the second driving transistor is electrically connected to the negative terminal of the power supply, the emitter of the first driving transistor is electrically connected to the emitter of the second driving transistor, and the emitters of the first driving transistor and the second driving transistor are electrically connected to the power amplifier transistor.

[0017] In one possible design, the power amplifier transistor includes: a first power amplifier transistor and a second power amplifier transistor; The base of the first power amplifier transistor is electrically connected to the emitter of the first driver transistor, and the base of the second power amplifier transistor is electrically connected to the emitter of the second driver transistor. The collector of the first power amplifier transistor is electrically connected to the positive terminal of the power supply, and the collector of the second power amplifier transistor is electrically connected to the negative terminal of the power supply. The emitter of the first power amplifier transistor is electrically connected to the emitter of the second power amplifier transistor through two series-connected resistors, an eighth resistor and a ninth resistor. The common terminal of the eighth resistor and the ninth resistor serves as the output terminal of the power amplifier transistor.

[0018] In one possible design, the static bias signal is used to control the static current of the power amplifier tube, and the static current is between 400mA and 600mA.

[0019] Beneficial effects: (1) This invention employs an innovative full-time amplitude domain pulse-by-pulse biasing scheme to achieve a 360° floating full-time amplitude domain wrapping of the original audio signal by the dynamic bias signal. In this way, on the one hand, the pulse broadening technology is used to achieve precise pre-tracking control of the original audio signal by the dynamic bias signal, thereby maximizing the dynamic and precise power reduction of the system. On the other hand, it can realize the function of turning on the bias signal first and then the audio signal in the rising segment of the audio signal, and turning off the audio signal first and then the bias signal in the falling segment of the audio signal. Based on this, the original audio signal can be avoided. Because of the direct physical contact between the amplifier tube and the tube wall, deformation can occur, thereby dynamically eliminating various nonlinear distortion problems such as switching distortion and transient distortion. In addition, this invention does not require frequency domain processing such as transformation of the original audio signal, thus preserving the original audio signal to the greatest extent and further ensuring the quality of the output audio. Therefore, this invention effectively solves the long-standing contradiction between power consumption and the pursuit of high-quality music effects in Class A amplifiers, effectively improving the energy efficiency of the amplifier system while ensuring excellent audio performance.

[0020] (2) The full-link lossless Class A audio power amplifier provided by the present invention has a static current value of 400mA to 600mA for its power amplifier tube. Compared with the traditional technology that uses a static current of 2A (output effective power of 60W), the static power consumption of the power amplifier of the present invention is only 20%-30% of that of the traditional Class A power amplifier, thus realizing the function of static power reduction. In this way, the combination of static power reduction and the aforementioned dynamic power reduction can further reduce the power consumption of the system.

[0021] (3) This invention realizes full-link Class A amplification, namely Class A follower current amplification in the input stage, Class A differential voltage amplification in the intermediate stage and Class A push-pull power amplification in the output stage; therefore, it realizes lossless Class A high-fidelity amplification throughout the entire process, which powerfully promotes new development and breakthroughs in Class A audio power amplification technology. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier provided in an embodiment of the present invention; Figure 2 This is a connection circuit diagram of the lossless and bias audio processing circuit and the differential amplifier circuit provided in an embodiment of the present invention; Figure 3 A specific circuit diagram of the optoelectronic bridge isolation transmission circuit provided in the embodiments of the present invention; Figure 4 This is a schematic diagram of the full-time amplitude domain pulse-by-pulse bias circuit provided in an embodiment of the present invention. Detailed Implementation

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0024] It should be understood that although the terms first, second, etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit, without departing from the scope of the exemplary embodiments of the invention.

[0025] It should be understood that the term "and / or" that may appear in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" that may appear in this document describes another relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " that may appear in this document generally indicates that the related objects before and after it are in an "or" relationship.

[0026] Example: See Figures 1-4 As shown, the full-link lossless Class A audio power amplifier with full-time amplitude domain bias provided in this embodiment may include, but is not limited to, a lossless and bias audio processing circuit, a differential amplifier circuit, a voltage amplifier circuit, an opto-bridge isolation circuit, and a full-time amplitude domain pulse-by-pulse bias circuit. The aforementioned lossless and bias audio processing circuit primarily filters out some interference in the audio signal, performs Class A follower current amplification on the original audio signal, and outputs it to the subsequent circuitry. Simultaneously, it generates a bias audio signal based on the original audio signal and outputs it to the subsequent opto-bridge isolation circuit. Specifically, the input terminal of the lossless and bias audio processing circuit receives the original audio signal and performs Class A follower current amplification on it (Class A follower current amplification is a method where, throughout the entire cycle of the signal (both positive and negative half-cycles of a sine wave), no power output element of the amplifier experiences current cutoff (i.e., stops output), resulting in a first lossless audio signal output to the differential amplifier circuit, and generates a bias audio signal based on the original audio signal and outputs it to the opto-bridge isolation circuit. Of course, the so-called lossless audio signal in this invention is relative, referring only to the audio signal that has only undergone amplitude domain amplification, without frequency domain processing, and without delay.

[0027] After obtaining the first lossless audio signal, it can be input to a differential amplifier circuit for differential amplification. That is, the differential amplifier circuit is used to differentially amplify the first lossless audio signal to obtain a second lossless audio signal. The second lossless audio signal is then amplified by a voltage amplifier circuit and output to the base of the power amplifier driver transistor (i.e., a third lossless audio signal is output to the base of the power amplifier transistor after voltage amplification). In this embodiment, the first lossless audio signal undergoes two voltage amplifications: one is differential voltage amplification, and the other is voltage amplification by the voltage amplifier circuit. At this time, the third lossless audio signal can be output to the base of the power amplifier driver transistor (i.e., the third lossless audio signal is the audio signal generated after voltage amplification of the second lossless audio signal). This allows for subsequent control of the power amplifier driver transistor in conjunction with the dynamic bias signal output by the full-time amplitude domain pulse-by-pulse bias circuit.

[0028] Simultaneously, when the bias audio signal enters the opto-bridge circuit, it can be transmitted with opto-isolation. That is, the opto-bridge isolation circuit is used to opto-isolate the bias audio signal to obtain a delayed audio signal, and outputs the delayed audio signal to the full-time amplitude domain pulse-by-pulse bias circuit. Specifically, the opto-bridge circuit is a balanced opto-bridge isolation circuit. Its function is to transmit the input bias audio signal with opto-isolation. During the isolation process, the audio signal will have an inherent delay on the order of nanoseconds, thus outputting an audio signal with minimal distortion, called the delayed audio signal. This distortion does not affect the use of the delayed audio signal as a bias signal at all. Furthermore, because the subsequent stage uses pulse broadening technology, this distortion will not affect the bias effect of the system at all. The specific structure of the opto-bridge circuit will be described in detail below.

[0029] After obtaining the delayed audio signal, the full-time amplitude domain pulse-by-pulse bias circuit can be used to generate a leading and lagging "full-time amplitude domain pulse-by-pulse bias signal" (also known as a dynamic bias signal) with a phase angle greater than 180° in the positive and negative half-cycles of the third lossless audio signal, respectively. Then, combined with the third lossless audio signal output by the aforementioned voltage amplifier circuit, the power amplifier tube can be driven.

[0030] Specifically, the full-time amplitude domain pulse-by-pulse bias circuit is used to generate a first dynamic bias signal with a phase angle greater than 180° during the positive half-cycle of the third lossless audio signal, and a second dynamic bias signal with a phase angle greater than 180° during the negative half-cycle, based on the delayed audio signal. The two dynamic bias signals are then output to the base of the power amplifier driver transistor. Simultaneously, the collector of the power amplifier driver transistor is electrically connected to the power supply, and the emitter of the power amplifier driver transistor is electrically connected to the power amplifier transistor. Based on this, the dynamic bias signal and the third lossless audio signal can be used together to control the power amplifier driver transistor, thereby driving the power amplifier transistor.

[0031] In this embodiment, the full-time amplitude domain pulse-by-pulse bias circuit employs an innovative pulse broadening technique to generate a leading and a lagging dynamic bias signal with a phase angle greater than 180° in the positive and negative half-cycles of the audio signal, respectively. Since the phase angle of the dynamic bias signal is greater than 180°, the aforementioned dynamic bias signal can achieve full-time domain coverage of the third lossless audio signal. Furthermore, by appropriately adjusting the amplitude of this dynamic bias signal, full-amplitude domain coverage of the third lossless audio signal can be achieved, thus realizing full-time amplitude domain coverage of the audio signal. In other words, the bias signal completely envelops the entire third lossless audio signal. For example, when the audio signal is 20kHz, the half-cycle phase angle of the dynamic bias signal is greater than 180°, leading and lagging the original audio signal by at least 2µs in half a cycle. When the audio signal is 20Hz, the half-cycle phase angle of the dynamic bias signal is also greater than 180°, leading and lagging the audio signal by at least 2ms in half a cycle. This allows the dynamic bias signal to completely "float" and envelop the original audio signal in more than 360° in two dimensions.

[0032] Thus, when driving the power amplifier driver tube, during the rising phase of the audio signal (i.e., the rising edge of the signal), the rising edge of the dynamic bias signal is passed first, followed by the rising edge of the third lossless audio signal. Similarly, during the falling phase of the audio signal, the falling edge of the third lossless audio signal is passed first (because the bias signal will cover the audio signal), followed by the falling edge of the dynamic bias signal. Therefore, within one signal cycle, the function of turning on the bias signal first and then the audio signal during the rising phase of the audio signal, and ending the audio signal first and then the bias signal during the falling phase of the audio signal can be achieved. Based on this, the dynamic bias signal acts like an "isolation field," causing the original audio signal to "suspend" in the "internal space" of the power amplifier tube, avoiding the possibility of "deformation" caused by direct "physical" contact between the original audio signal and the "tube wall" of the power amplifier tube. This maximizes the guarantee that the power amplifier system can reliably operate in Class A mode under complex conditions of full frequency band and large dynamic range, thereby dynamically eliminating various nonlinear distortion problems such as switching distortion and transient distortion.

[0033] Meanwhile, the dynamic bias signal is generated based on the delayed audio signal, which is generated by isolating the original audio signal through an opto-bridge. Therefore, when the original audio signal changes, the dynamic bias signal also changes accordingly. That is, the dynamic bias signal can accurately follow the changes of the original audio signal (its amplitude is positively correlated with the original audio signal). In this way, the magnitude of the dynamic bias signal can be dynamically adjusted according to the amplitude of the audio signal. Based on this, this embodiment realizes the precise pre-tracking control of the original audio signal by the dynamic bias signal, thereby maximizing the dynamic and precise power consumption reduction of the system.

[0034] Thus, through the aforementioned description of the overall architecture of the end-to-end lossless Class A audio power amplifier, this invention not only reduces system power consumption but also dynamically eliminates various nonlinear distortion problems such as switching distortion and transient distortion. It avoids the problems of artificial noise and delay introduced by traditional technologies due to multiple transformations of the original audio signal. Therefore, this invention can significantly improve the fidelity and power efficiency of Class A audio power amplifiers (i.e., reduce power consumption), thereby promoting new developments and breakthroughs in audio power amplification technology.

[0035] In one possible design, this embodiment provides the detailed circuit structure of the aforementioned circuits, as shown below.

[0036] First, we will provide one circuit structure for lossless and biased audio processing: In practical applications, lossless and biased audio processing circuits may include, but are not limited to, a first operational amplifier U1A and a second operational amplifier U1B; wherein the connection structure of the aforementioned two operational amplifiers is as follows: See Figure 2 As shown, the non-inverting input terminal of the second operational amplifier U1B is electrically connected to the adjustment terminal of potentiometer RP1. One end of the potentiometer RP1 (i.e., a fixed end) is electrically connected to the audio interface J1 (the ground terminal of J1 is grounded) for receiving the original audio signal through the first resistor R8. The output terminal of the second operational amplifier U1B is connected to the inverting input terminal. The output terminal of the second operational amplifier U1B outputs the first lossless audio signal, and the other end of the potentiometer RP1 is grounded (i.e., the other fixed terminal of RP1 is grounded).

[0037] Meanwhile, the inverting input of the first operational amplifier U1A is electrically connected to the non-inverting input of the second operational amplifier U1B (the inverting input of U1A is connected to the non-inverting input of U1B through resistor R9). The non-inverting input of the first operational amplifier U1A is grounded (its non-inverting input is grounded through resistor R5). The output of the first operational amplifier U1A is connected to its inverting input through resistor R10, and the output of the first operational amplifier U1A outputs a bias audio signal.

[0038] Of course, in this embodiment, the two operational amplifiers are also equipped with peripheral circuitry, see [link to documentation]. Figure 2 As shown, the positive power supply terminal of the first operational amplifier U1A is electrically connected to one end of capacitor C4, one end of capacitor C1, and the positive terminal of VCC power supply (5V power supply positive terminal), and the other ends of capacitors C4 and C1 are grounded respectively; similarly, for the second operational amplifier U1B, its negative power supply terminal is electrically connected to one end of capacitor C9, one end of capacitor C8, and the VEE power supply (5V power supply negative terminal), and the other ends of capacitors C9 and C8 are grounded respectively.

[0039] Thus, the operation of the aforementioned lossless and biased audio processing circuit is as follows: The original audio signal is input from the J1 socket, and is divided by the first resistor R8 and the potentiometer RP1 (adjusting the resistor R8 can change the magnitude of the original audio signal sent to the potentiometer RP1. Regardless of the signal source, the maximum peak-to-peak voltage of the original audio signal obtained on RP1 should be less than or equal to 2.2Vp-p by adjusting the resistor R8). After RP1 controls the volume, it splits into two paths: one path sends the original audio signal to U1B for follower current amplification to output the first lossless audio signal, and the other path sends the original audio signal to U1A for inverting voltage amplification to output the biased audio signal.

[0040] Based on this, the aforementioned two operational amplifiers can be used to achieve current-following amplification of the original audio signal and to generate a bias audio signal; then, the current-amplified audio signal can be output to the differential amplifier circuit for voltage amplification.

[0041] Optionally, one of the circuit structures of the differential amplifier circuit disclosed below.

[0042] In specific implementations, the differential amplifier circuit described in the example may include, but is not limited to, the following: a first transistor Q4, a second transistor Q6, a third transistor Q5, and a fourth transistor Q7; wherein the connection structure of the aforementioned four transistors is as follows: See Figure 2 As shown, the bases of the first transistor Q4 and the second transistor Q6 are both electrically connected to the first output terminal of the lossless and biased audio processing circuit (the first output terminal is used to output the first lossless audio signal, i.e., the bases of Q4 and Q6 are connected to the output terminal of U1B). The collectors of the first transistor Q4 and the third transistor Q5 are electrically connected to the positive terminal of the power supply (in this embodiment, the collector of Q4 is connected to one end of the first inductor L1 through resistor R2, and the collector of Q5 is also connected to one end of the first inductor L1 through resistor R3, while the other end of the first inductor L1 is connected to the positive terminal of the power supply). The collectors of the second transistor Q6 and the fourth transistor Q7 are electrically connected to the negative terminal of the power supply. Similarly, the collectors of Q6 and Q7 are also electrically connected to one end of the second inductor L2 through a resistor (i.e., ...). Figure 2 (R18 and R19 in the middle); while the other end of the second inductor L2 is electrically connected to the negative terminal of the power supply.

[0043] Furthermore, the emitters of the first transistor Q4 and the third transistor Q5 are both electrically connected to the negative terminal of the power supply through the second resistor R17, and the emitters of the second transistor Q6 and the fourth transistor Q7 are both electrically connected to the positive terminal of the power supply through the third resistor R1. Simultaneously, the bases of the third transistor Q5 and the fourth transistor Q7 are electrically connected to one end of the fourth resistor R11, where the other end of the fourth resistor R11 is grounded through the first electrolytic capacitor C6. The base of the fourth transistor Q7 is also electrically connected to the output terminal of the power amplifier transistor through the fifth resistor R15 (the fifth resistor R15 serves as a voltage negative feedback terminal to connect to the power amplifier). The output terminals of the differential amplifier circuit are: the collector of the first transistor Q4 and the collector of the second transistor Q6, which serve as the output terminals of the differential amplifier circuit, and output the second lossless audio signal (i.e., when the first lossless audio signal input to Q4 is a positive half-cycle signal, Q4 outputs a negative half-cycle second lossless audio signal; when the first lossless audio signal input to Q6 is its negative half-cycle signal, Q6 outputs a positive half-cycle second lossless audio signal; of course, if the input to Q4 is a negative half-cycle signal, the output is a positive half-cycle second lossless audio signal; if the input to Q6 is a positive half-cycle audio signal, the output is a negative half-cycle second lossless audio signal).

[0044] In this embodiment, the common connection terminal of the first inductor L1 with R3, R2, and R1 is also electrically connected to one end of capacitors C2 and C3, respectively, and the other ends of capacitors C2 and C3 are grounded respectively; similarly, the connection structure of the common connection terminal of the second inductor L2 with R19, R18, and R17 is also the same, as can be found in [reference]. Figure 2 As shown, it will not be elaborated further here.

[0045] Thus, as explained above, transistors Q4, Q5, Q6, and Q7 can be used to amplify Class A voltages with low temperature drift, thereby increasing the voltage amplitude, providing a larger output signal, and achieving the goal of increasing signal gain.

[0046] After differential voltage amplification is completed, secondary voltage amplification can be performed. That is, the differential amplifier circuit will transmit the output audio signal to the voltage amplifier circuit, and after voltage amplification by transistors with Q1 and Q8 as the core, the lossless original audio signal (i.e. the third lossless audio signal) will be output from the IO1 port.

[0047] In specific implementation, one of the circuit structures of the disclosed voltage amplifier circuit is as follows: In this embodiment, the voltage amplifier circuit may include, but is not limited to, a fifth transistor Q1 and a sixth transistor Q8; wherein the connection structure of the aforementioned transistors Q1 and Q8 is as follows: See Figure 2As shown, the base of the fifth transistor Q1 is electrically connected to the collector of the first transistor Q4, and the base of the sixth transistor Q8 is electrically connected to the collector of the second transistor Q6. The emitter of the fifth transistor Q1 is electrically connected to one end of the first inductor L1 through the sixth resistor R4, and the other end of the first inductor L1 is electrically connected to the positive terminal of the power supply. Similarly, the emitter of the sixth transistor Q8 is electrically connected to one end of the second inductor L2 through the seventh resistor R20, and the other end of the second inductor L2 is electrically connected to the negative terminal of the power supply. Furthermore, the first inductor L1, together with capacitors C2 and C3, forms an LC low-pass filter to achieve low-pass filtering. Similarly, the second inductor L2, together with capacitors C10 and C1, also forms a low-pass filter, the structure of which can be found in [reference needed]. Figure 2 As shown.

[0048] Meanwhile, the collectors of the fifth transistor Q1 and the sixth transistor Q8 serve as the output terminals of the voltage amplifier circuit, outputting a third lossless audio signal to the base of the power amplifier driver transistor; for details, see... Figure 2 As shown, the collectors of the fifth transistor Q1 and the sixth transistor Q8 are connected to the IO1 port for outputting a third lossless audio signal from the IO1 port. Furthermore, the collectors of the fifth transistor Q1 and the sixth transistor Q8 are also floating (i.e., independently grounded, meaning not connected to...). Figure 2 (The grounding wires of all other devices in the circuit are common to the ground); furthermore, the aforementioned IO1 port is connected to the base of the power amplifier driver transistor through resistors R6 and R13 respectively.

[0049] Therefore, the third lossless audio signal output by the voltage amplification circuit can be output to the base of the power amplifier driver transistor through the I01 port, thereby driving the power amplifier driver transistor in combination with the dynamic bias signal output by the full-time amplitude domain pulse-by-pulse bias circuit.

[0050] As described above, the full-link lossless Class A audio power amplifier provided in this embodiment achieves current amplification at the input stage and differential voltage amplification at the intermediate stage. Based on this, the effects of temperature changes and power supply ripple changes on the audio signal are resolved. At the same time, after differential voltage amplification, a voltage amplification circuit composed of two transistors, Q1 and Q8, is used to perform secondary voltage amplification. This circuit operates in Class A mode (i.e., the transistors are always in the on state), thus ensuring the high quality of the original audio signal.

[0051] After the original audio signal has been amplified in two stages, the bias audio signal can be transmitted in an opto-isolated manner using an opto-bridge isolation circuit, thereby outputting a delayed audio signal for subsequent use in generating a dynamic bias signal.

[0052] One of the circuit structures of the opto-bridge isolation circuit is disclosed below: In this embodiment, the example opto-bridge isolation circuit is a balanced opto-bridge isolation circuit, see [link to relevant documentation]. Figure 3 As shown, after the bias audio signal passes through the opto-bridge isolation transmission circuit, a delayed audio signal with a delay of ns is generated, and the signal waveform is the same as the bias audio signal (that is, the generated signal has very little distortion).

[0053] In practical implementation, the opto-bridge isolation transmission circuit adopts an innovative circuit topology structure, which consists of two optocouplers forming an H-type bridge circuit. That is, the light-emitting diodes in the two optocouplers are connected in series to form the input terminal of the opto-bridge (referred to as the input bridge). In the input bridge, the positive terminal of the upper light-emitting diode is connected to the +V1 power supply, and the negative terminal of the lower light-emitting diode is connected to the -V1 power supply. The input signal is input from the series connection of the two light-emitting diodes. At the same time, the output terminal of the opto-bridge (referred to as the output bridge) is formed by the photodiodes in the two optocouplers connected in series. In the output bridge, the negative terminal of the upper photodiode is connected to the +V2 power supply, and the positive terminal of the lower photodiode is connected to the -V2 power supply. The output signal is output from the series connection of the two photodiodes.

[0054] Thus, the advantages of the H-type opto-bridge with the aforementioned groundbreaking circuit topology are as follows: First, since the output signal is output by a photodiode, the signal transmission rate will be greatly improved, the signal transmission delay will be greatly reduced (ns-level delay), and the signal distortion will also be greatly reduced; second, it can realize single-ended input of the input signal and single-ended output of the output signal; third, the opto-bridge with the new topology can realize high-fidelity isolated transmission of arbitrary waveform signals such as DC signals, AC signals, analog signals, and digital signals.

[0055] For details on the specific circuit structure of the opto-bridge isolated transmission circuit, please refer to [link / reference]. Figure 3 As shown, the circuit consists of two optocouplers U3 and U7 forming an H-type bridge circuit. The LEDs in U3 and U7 are connected in series with potentiometer R81 to form the input terminal (input bridge) of a symmetrical optocoupler bridge. Potentiometer R81 serves two purposes: firstly, it acts as a current-limiting resistor for the LEDs; secondly, when the input signal is zero, adjusting R81 makes the output signal zero as well. In the input bridge, the positive terminal of LED U3 is connected to the +V1 power supply, and the negative terminal of LED U7 is connected to the -V1 power supply. The bias audio signal at port IO2 is input from the center sliding terminal of potentiometer R81, ensuring the circuit's symmetry and balance. The output terminal (output bridge) of the optocoupler bridge consists of photodiodes in U3 and U7 connected in series. In the output bridge, the negative terminal of the upper photodiode is connected to the +V2 power supply, and the positive terminal of the lower photodiode is connected to the -V2 power supply. The output signal is output from the series connection of the two photodiodes (the delayed audio signal is output from port IO22).

[0056] Furthermore, the aforementioned opto-bridge isolation transmission circuit is equipped with two independent and regulated dual power supplies, which provide a stable voltage +V1 / -V1 to the input bridge and a stable voltage +V2 / -V2 to the output bridge, ensuring the stable and reliable operation of the opto-bridge.

[0057] Thus, the working principle of the aforementioned opto-bridge isolation transmission circuit is as follows: Assuming the bias audio signal input to port IO2 is zero, since the upper and lower arms of the opto-bridge are symmetrical, R81 is finely adjusted to make the delayed audio signal output from port IO22 of the output bridge also zero. Assuming the input signal voltage is greater than zero, the LED in U3 emits less light due to the reduced voltage drop, thus increasing the internal resistance of the photodiode in U3. Simultaneously, the LED in U7 emits more light due to the increased voltage drop, thus decreasing the internal resistance of the photodiode in U7. Under the combined effect of these two factors, the output delayed audio signal voltage decreases to a negative voltage output. Assuming the input signal voltage is less than zero, the LED in U3 emits more light due to the increased voltage drop, thus decreasing the internal resistance of the photodiode in U3. Simultaneously, the LED in U7 emits less light due to the reduced voltage drop, thus increasing the internal resistance of the photodiode in U7. Under the combined effect of these two factors, the output delayed audio signal voltage rises to a positive voltage output.

[0058] By describing the structure of the aforementioned opto-bridge isolation circuit, an innovative H-type bridge circuit can be used to achieve delay isolation transmission of bias audio signals at the ns level (800ns), resulting in a delay audio signal with minimal distortion.

[0059] After obtaining the delayed audio signal, it can be output to the full-time amplitude domain pulse-by-pulse bias circuit to generate a dynamic bias signal with a phase greater than 180° in each of the positive and negative half-cycles of the third lossless audio signal, so as to realize the full-time amplitude domain wrapping of the third lossless audio signal based on the dynamic bias signal.

[0060] In specific implementation, the following discloses the specific working process of the full-time amplitude domain pulse-by-pulse bias circuit: the full-time amplitude domain pulse-by-pulse bias circuit is used to receive the externally input static bias signal; then, it is used to generate a first comprehensive bias signal based on the static bias signal and the first dynamic bias signal, and to generate a second comprehensive bias signal based on the static bias signal and the second dynamic bias signal, and output the first comprehensive bias signal and the second comprehensive bias signal to the base of the power amplifier driver transistor; in this way, the first comprehensive bias signal and the second comprehensive bias signal, as well as the third lossless audio signal output by the aforementioned voltage amplification circuit, can be used to drive the power amplifier driver transistor.

[0061] Furthermore, the specific structure of the full-time amplitude domain pulse-by-pulse bias circuit is disclosed below: In this embodiment, the example full-time amplitude domain pulse-by-pulse bias circuit may include, but is not limited to: a reference source SC4, a positive pulse broadening circuit SC1, a negative pulse broadening circuit SC7, a detection and delay circuit SC6, a first electronic switch SC2, a second electronic switch SC8, a subtractor SC3, and an adder SC9. The operation of each of the aforementioned circuits is as follows: See Figure 4 As shown, reference source SC4 is electrically connected to the input terminals of the positive pulse broadening circuit SC1 and the negative pulse broadening circuit SC7, respectively, to provide reference voltages to the positive pulse broadening circuit SC1 and the negative pulse broadening circuit SC7; the input terminal of the positive pulse broadening circuit SC1 is also electrically connected to the output terminal of the opto-bridge isolation circuit, to generate a half-wave audio signal with a negative half-cycle greater than 180° as a second dynamic bias signal based on the delayed audio signal and the reference voltage, and output it to the first electronic switch SC2; similarly, the input terminal of the negative pulse broadening circuit SC7 is also electrically connected to the output terminal of the opto-bridge isolation circuit, to generate a half-wave audio signal with a positive half-cycle greater than 180° as a first dynamic bias signal based on the delayed audio signal and the reference voltage, and output it to the second electronic switch SC8.

[0062] In this embodiment, the aforementioned positive pulse broadening circuit SC1 and negative pulse broadening circuit SC7 are essentially non-zero amplifiers. They are used to compare the reference voltage with the delayed audio signal and then amplify it in reverse phase, thereby outputting an asymmetrical audio signal (i.e., a half-wave audio signal) with a negative half-cycle phase greater than 180° from SC1 and an asymmetrical audio signal with a positive half-cycle phase greater than 180° from SC7. In this way, the aforementioned two dynamic bias signals can be generated using the aforementioned non-zero amplifiers.

[0063] Simultaneously, the input terminal of the detection and delay circuit SC6 is electrically connected to the output terminal of the opto-bridge isolation circuit. The output terminal of the detection and delay circuit SC6 is electrically connected to the first electronic switch SC2 and the second electronic switch SC8, respectively. The first electronic switch SC2 is electrically connected to the subtractor SC3, and the second electronic switch SC8 is electrically connected to the adder SC9. Thus, when the delayed audio signal is detected from the opto-bridge isolation circuit, the aforementioned detection and delay circuit simultaneously outputs a high-level signal (e.g., 100ms) for a preset duration to the first and second electronic switches to turn them on, thereby transmitting the dynamic bias signal to the adder and subtractor. Similarly, when the delayed audio signal is detected to disappear, it can delay for a preset duration (e.g., 100ms) and simultaneously output a low-level signal to the first and second electronic switches to simultaneously turn them off, so that the adder and subtractor only transmit the received static bias signal to the base of the power amplifier driver transistor.

[0064] After the dynamic bias signal is transmitted, a 1x adder and a 1x subtractor can be used to perform operations on the dynamic bias signal and the static bias signal. Specifically, both the 1x subtractor and the 1x adder are electrically connected to a static bias signal generation circuit to receive the static bias signal output by the static bias signal generation circuit. The 1x subtractor generates a second composite bias signal based on the static bias signal and the second dynamic bias signal, and outputs it to the base of the power amplifier driver transistor. Similarly, the 1x adder generates a first composite bias signal based on the static bias signal and the first dynamic bias signal, and outputs it to the base of the power amplifier driver transistor. In this way, it is equivalent to combining the static bias signal and the dynamic bias signal output by the full-time amplitude domain pulse-by-pulse bias circuit, and combining them with the third lossless audio signal, to jointly control the power amplifier driver transistor.

[0065] Furthermore, in this embodiment, the static bias signal generation circuit may include, but is not limited to, potentiometer RP2 and resistor R01, see [link to documentation]. Figure 4 As shown, one end of resistor R01 is electrically connected to a 12V power supply, and the other end of resistor R01 is electrically connected to one fixed terminal of potentiometer RP2. The other fixed terminal of potentiometer RP2 is connected to floating ground, and the middle sliding terminal of potentiometer RP2 is electrically connected to a 1x adder SC9 and a 1x subtractor SC3, respectively. Thus, based on this circuit, a static bias signal can be output to the 1x adder SC9 and the 1x subtractor SC3. Optionally, for example, the aforementioned static bias signal can control the static current of the power amplifier tube, and the static current value is between 400mA and 600mA. Thus, compared with the traditional Class A power amplifier that requires 2A of static current for an effective output power of 60W, this embodiment can achieve the purpose of significantly reducing static power consumption.

[0066] Thus, two signals are superimposed at the base of the power amplifier driver transistor: a composite bias signal and a third lossless audio signal. As previously explained, the dynamic bias signal has a phase greater than 180°, which can completely envelop the third lossless audio signal across its entire amplitude domain. Therefore, the generated composite bias signal also has a phase greater than 180°, allowing it to also envelop the third lossless audio signal. Based on this, within one signal cycle, the bias signal can be activated before the audio signal during the rising phase, and the audio signal can be deactivated before the bias signal during the falling phase. This allows the original audio signal to "float" within the "internal space" of the power amplifier transistor, preventing deformation caused by direct "physical" contact between the original audio signal and the transistor's "wall," thereby dynamically eliminating various nonlinear distortion problems such as switching distortion and transient distortion.

[0067] Therefore, through a detailed structural description of the aforementioned full-time amplitude domain pulse-by-pulse bias circuit, its working principle is as follows: The SC1 and SC7 circuits contain a non-zero amplifier. Their function is to compare the delayed audio signal with the ±10mV reference voltage sent from the reference source SC4, and then amplify them in reverse phase. The SC1 module outputs an asymmetrical audio signal with a negative half-cycle greater than 180°, and the SC7 module outputs an asymmetrical audio signal with a positive half-cycle greater than 180°. This is the full-time amplitude domain pulse-by-pulse bias signal (i.e., dynamic bias signal).

[0068] Meanwhile, the SC6 circuit detects delayed audio signals. When a delayed audio signal is detected, the circuit immediately outputs a high level for 100ms. If a delayed audio signal is continuously detected within 100ms, the circuit will continue to output a high level. If no delayed signal is detected within 100ms, it is determined that the power amplifier has no audio signal input. The SC6 circuit will output a low level approximately 100ms after the last delayed audio signal pulse disappears. Similarly, if a delayed audio signal is detected again during the low level period, the SC6 will immediately output a high level, achieving the so-called rapid rise and slow fall action. Ultimately, this achieves the engineering design goal of dynamic pulse-by-pulse bias when there is an audio signal and static small bias when there is no signal.

[0069] The functions of circuits SC2 and SC8 are as follows: first, to extract the negative half-cycle dynamic bias signal (greater than 180°) and the positive half-cycle dynamic bias signal (greater than 180°) respectively; second, to act as an electronic switch controlled by circuit SC6. When circuit SC6 detects a delayed audio signal, the electronic switch opens, sending the dynamic bias signal to the next stage module; when circuit SC6 detects no delayed audio signal, the electronic switch opens, and no dynamic bias signal is output. RP2 is a potentiometer used to adjust the quiescent current of the power amplifier. SC3 is a subtractive operational amplifier with a 1x amplification. When SC3 has no dynamic bias signal input, it indicates no audio input, and the power amplifier is in a quiescent state, with only a quiescent bias signal output to the first driver transistor Q2. When SC3 has a dynamic bias signal input, it indicates audio input, and the power amplifier is in a dynamic state. At this time, the SC3 module will perform calculations on the dynamic and quiescent bias signals, outputting a combined bias signal to driver transistor Q2.

[0070] Similarly, SC9 is an adder operational amplifier with a 1x amplification. When SC9 has no dynamic bias signal input, it means there is no audio input and the power amplifier is in a static state. At this time, only the static bias signal is output to the driver transistor Q9. When SC9 has a dynamic bias signal input, it means there is audio input and the power amplifier is in a dynamic state. At this time, SC9 will perform calculations on the dynamic bias signal and the static bias signal and output a combined bias signal to the second driver transistor Q9.

[0071] Specifically, the full-time amplitude domain pulse-by-pulse bias circuit is an active circuit that requires an independent dual 12V power supply and an independent (floating) ground. This floating ground is not connected to the ground of other circuits, and the third lossless audio signal is connected to this floating ground.

[0072] As explained above, the delayed audio signal is 800ns slower than the original audio signal. However, due to the pulse broadening technology used in this embodiment, the phase angle of the half-cycle of the dynamic bias signal evolved from the delayed audio signal is greater than 180°. Therefore, it can achieve full-time amplitude domain wrapping of the original audio signal. Taking the audio signal at 20kHz as an example, the dynamic bias signal is broadened by at least 2µs forward and backward. In other words, the dynamic bias signal is actually more than 1µs ahead and more than 2µs behind the original audio signal. Moreover, the lower the frequency of the audio signal, the longer the lead and lag time. Based on this, the dynamic bias signal achieves a 360° "floating" full-time amplitude domain wrapping of the original audio signal. Thus, in the rising segment of the audio signal, the dynamic bias signal is turned on first and then the audio signal is turned on. In the falling segment of the audio signal, the audio signal is turned off first and then the dynamic bias signal is turned off. This achieves dynamic elimination of various distortion problems such as switching distortion and transient distortion.

[0073] Furthermore, this embodiment employs pulse broadening technology to achieve precise pre-tracking control of the original audio signal by the dynamic bias signal, thereby maximizing the dynamic and precise power consumption reduction of the system.

[0074] The principle behind achieving energy saving is as follows: This embodiment is essentially a "combined bias Class A power amplifier with static fixed bias and dynamic pulse-by-pulse bias". That is, in the static state, the power amplifier tube has a static current of 400-600mA to maintain the basic characteristics of the Class A power amplifier. In the dynamic state, the "static current" of the power amplifier tube is adjusted according to the lead and lag of the audio signal amplitude (the dynamic "static current" increases when the signal is large and decreases when the signal is small), avoiding the power consumption waste of high static current throughout the traditional pure Class A power amplifier.

[0075] Specifically, when there is no signal, the power amplifier tube has a fixed quiescent current of 400-600mA to ensure low power consumption of the power amplifier in the quiescent state.

[0076] When there is a dynamic audio signal, the dynamic bias signal, which is positively correlated with the amplitude of the input audio, is extracted through audio signal isolation and processing and superimposed on the static bias signal. That is, the dynamic bias is linked with the audio signal in real time (small dynamic bias for small signals and large dynamic bias for large signals). This ensures that the two power amplifier tubes operate in Class A mode when there is a large signal (avoiding both clipping distortion and crossover distortion), and also ensures that the total bias current (static + dynamic) meets the Class A bias conditions when there is a small signal, while the power consumption current is still much lower than the fixed high static current of traditional pure Class A power amplifiers, thus achieving adaptive power consumption optimization in dynamic scenarios.

[0077] The core logic of dynamic power saving is as follows: Traditional pure Class A power amplifiers need to maintain a high quiescent current to meet peak demand (e.g., 2A quiescent current is required when the output power is 60W) in order to cover the maximum output power, and there is no power saving even when there is a small signal. In this embodiment, the dynamic bias signal is superimposed on the static bias signal only when there is an input audio signal, and together they control the power amplifier tubes to increase the "quiescent current" of the dynamic variable, so as to ensure that the two power amplifier tubes are conducting throughout the entire range. When there is a small signal or no signal, the total bias current is only the basic static value (400~600mA), which significantly reduces the power consumption in non-peak signal scenarios.

[0078] More specifically, this embodiment uses a full-time amplitude domain pulse-by-pulse bias circuit to superimpose the static bias signal and the dynamic bias signal and apply them together to the base of the power amplifier driver transistor, thereby achieving dynamic adaptive adjustment of the power amplifier output "static current": when there is no signal, the power amplifier output only maintains a low static current (400~600mA), and when there is a signal, the total "static current" of the power amplifier transistor (static current + incremental current brought by dynamic bias) changes in real time with the amplitude of the audio signal, ensuring that the power amplifier transistor works in the Class A amplification range throughout the entire process, while reducing power consumption in non-peak signal scenarios. That is, the dynamic bias signal is generated by the delayed audio signal, and the delayed audio signal is generated by the original audio signal after opto-isolation. Therefore, the dynamic bias signal is positively correlated with the amplitude of the audio signal. When there is a small signal or no signal, the total "quiescent current" of the power amplifier tube will vary around (400~600mA). When there is a large signal, the incremental current brought by the dynamic bias is increased to control the two power amplifier tubes to be in the conducting state throughout the entire process. This effectively avoids the waste of high power consumption of traditional Class A power amplifiers throughout the entire process, thus ensuring the quality of the output audio signal on the one hand, and improving the energy utilization efficiency under all operating conditions on the other hand.

[0079] The following example illustrates this using a specific usage scenario: No signal scenario: The dynamic bias signal is zero, and the static current is 400-600mA, which is much lower than the static current of traditional Class A power amplifiers, resulting in a significant reduction in power consumption.

[0080] In small signal scenarios (input audio signal less than 50mV): the dynamic bias signal is small, and the total "quiescent current" will vary around (400~600mA), which is still much lower than the quiescent current of traditional Class A power amplifiers, resulting in a significant reduction in power consumption.

[0081] In high-signal scenarios (input audio signal greater than 50mV): the dynamic bias signal increases synchronously (taking an effective output power of 60W as an example, the maximum incremental current of the power amplifier tube caused by the dynamic bias can reach (1.4A~1.6A), so the total "static current" = static current (400~600mA) + dynamic bias incremental current (1.4A~1.6A) = about 2A, which just meets the maximum peak static current bias requirement of Class A power amplifier when outputting 60W, ensuring no clipping and no crossover distortion).

[0082] When the signal disappears: the dynamic bias signal returns to zero, and the static current of the power amplifier tube automatically drops back to a low-power state of 400-600mA.

[0083] Therefore, after outputting the comprehensive bias signal based on the aforementioned full-time amplitude domain pulse-by-pulse bias circuit, the power amplifier driver transistor can be driven by combining it with the third lossless audio signal.

[0084] One of the circuit structures for the power amplifier driver transistor is disclosed below: In this embodiment, the power amplifier driver transistors may include, but are not limited to, a first driver transistor Q2 and a second driver transistor Q9; wherein the connection structure of the two driver transistors is as follows: See Figure 4 As shown, the base of the first driving transistor Q2 is electrically connected to the output terminal of the subtractor and the output terminal of the voltage amplifier circuit (i.e., connected to port IO1 through resistor R6), and the base of the second driving transistor Q9 is electrically connected to the output terminal of the adder and the output terminal of the voltage amplifier circuit (connected to port IO1 through resistor R13). The collector of the first driving transistor Q2 is electrically connected to the positive terminal of the power supply, the collector of the second driving transistor Q9 is electrically connected to the negative terminal of the power supply, the emitter of the first driving transistor Q2 is electrically connected to the emitter of the second driving transistor Q9 through resistor R02, and the emitters of the first driving transistor Q2 and the second driving transistor Q9 are electrically connected to the power amplifier transistor.

[0085] Meanwhile, the aforementioned power amplifier transistors include the first power amplifier transistor Q3 and the second power amplifier transistor Q10; see also Figure 4 As shown, the base of the first power amplifier transistor Q3 is electrically connected to the emitter of the first driver transistor Q2, and the base of the second power amplifier transistor Q10 is electrically connected to the emitter of the second driver transistor Q9. The collector of the first power amplifier transistor Q3 is electrically connected to the positive terminal of the power supply, and the collector of the second power amplifier transistor Q10 is electrically connected to the negative terminal of the power supply. The emitter of the first power amplifier transistor Q3 is electrically connected to the emitter of the second power amplifier transistor Q10 through two series-connected resistors R03 and R05. The common terminal of the eighth resistor R03 and the ninth resistor R05 serves as the output terminal of the power amplifier transistor, thereby enabling power amplifier output.

[0086] Based on the foregoing explanation, the conduction of Q2 and Q9 can be controlled by applying a combined bias signal and a third lossless audio signal to the bases of the first driving transistor Q2 and the second driving transistor Q9, thereby realizing the current amplification of the two power amplifier transistors Q3 and Q10, and ultimately achieving power amplification.

[0087] Therefore, through the detailed description above of the full-link lossless Class A audio power amplifier with full-time amplitude bias, this invention has the following beneficial effects: (1) Full-link Class A amplification: Class A follower current amplification in the input stage, Class A differential voltage amplification in the intermediate stage, and Class A push-pull power amplification with static fixed bias + dynamic pulse-by-pulse bias in the output stage.

[0088] (2) Sufficient static bias: static current 400mA~600mA (400mA when cold, 600mA when hot).

[0089] (3) Sufficient dynamic bias: An innovative full-time amplitude domain pulse-by-pulse bias scheme is adopted, resulting in sufficient dynamic bias increment current. Furthermore, because the dynamic bias signal achieves a 360° "floating" full-time amplitude domain wrap around the original audio signal, the advantages are: First, the use of pulse broadening technology enables precise pre-tracking control of the dynamic bias signal on the original audio signal, thereby maximizing the system's dynamic and precise bias; second, it enables the dynamic bias signal to be turned on before the audio signal in the rising phase of the audio signal, and the audio signal to be turned off before the dynamic bias signal in the falling phase of the audio signal; thus, the dynamic bias signal acts like an "isolation field," causing the original audio signal to "float" above the power supply. Within the "internal space" of the amplifier tube, the possibility of "deformation" caused by direct "physical" contact between the original audio signal and the "tube wall" of the amplifier tube is avoided. This ensures that the amplifier system can reliably operate in Class A mode under complex conditions with a wide frequency range and large dynamic range, and dynamically eliminates various distortion problems such as switching distortion and transient distortion. Based on this, the contradiction between the low power utilization efficiency of Class A amplifiers and the pursuit of high-quality music effects has been effectively resolved. While ensuring excellent audio performance, the energy efficiency of the amplifier system is effectively improved.

[0090] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier, characterized in that, include: A lossless and biased audio processing circuit, wherein the input terminal of the lossless and biased audio processing circuit is connected to the original audio signal, and is used to perform Class A follower current amplification processing on the original audio signal to obtain a first lossless audio signal output to a differential amplifier circuit, and is used to generate a biased audio signal based on the original audio signal and output it to an opto-bridge isolation circuit. The differential amplifier circuit is used to differentially amplify the first lossless audio signal to obtain the second lossless audio signal, and then amplify the second lossless audio signal through the voltage amplifier circuit and output it to the base of the power amplifier driver transistor. The opto-bridge isolation circuit is used to opto-isolate the bias audio signal to obtain a delayed audio signal, and output the delayed audio signal to the full-time amplitude domain pulse-by-pulse bias circuit. A full-time amplitude domain pulse-by-pulse bias circuit is used to generate a first dynamic bias signal with a phase angle greater than 180° during the positive half-cycle of a third lossless audio signal, and a second dynamic bias signal with a phase angle greater than 180° during the negative half-cycle, based on a delayed audio signal. The two dynamic bias signals are output to the base of a power amplifier driver transistor. The collector of the power amplifier driver transistor is electrically connected to a power supply, and the emitter of the power amplifier driver transistor is electrically connected to the power amplifier transistor. The third lossless audio signal is an audio signal generated by voltage amplification of the second lossless audio signal.

2. The volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier according to claim 1, characterized in that, The lossless and biased audio processing circuit includes: a first operational amplifier (U1A) and a second operational amplifier (U1B); The non-inverting input of the second operational amplifier (U1B) is electrically connected to the adjustment terminal of the potentiometer (RP1). One end of the potentiometer (RP1) is electrically connected to the audio interface for receiving the original audio signal through the first resistor (R8). The output terminal of the second operational amplifier (U1B) is connected to the inverting input terminal. The output terminal of the second operational amplifier (U1B) outputs the first lossless audio signal, and the other end of the potentiometer (RP1) is grounded. The inverting input terminal of the first operational amplifier (U1A) is electrically connected to the non-inverting input terminal of the second operational amplifier (U1B). The non-inverting input terminal of the first operational amplifier (U1A) is grounded. The output terminal of the first operational amplifier (U1A) is connected to the inverting input terminal. The output terminal of the first operational amplifier (U1A) outputs the bias audio signal.

3. The volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier according to claim 1, characterized in that, The differential amplifier circuit includes: a first transistor (Q4), a second transistor (Q6), a third transistor (Q5), and a fourth transistor (Q7). The base of the first transistor (Q4) and the base of the second transistor (Q6) are both electrically connected to the first output terminal of the lossless and biased audio processing circuit. The collectors of the first transistor (Q4) and the third transistor (Q5) are electrically connected to the positive terminal of the power supply, and the collectors of the second transistor (Q6) and the fourth transistor (Q7) are electrically connected to the negative terminal of the power supply. The first output terminal is used to output the first lossless audio signal. The emitters of the first transistor (Q4) and the third transistor (Q5) are both electrically connected to the negative terminal of the power supply through the second resistor (R17), and the emitters of the second transistor (Q6) and the fourth transistor (Q7) are both electrically connected to the positive terminal of the power supply through the third resistor (R1). The base of the third transistor (Q5) and the base of the fourth transistor (Q7) are electrically connected to one end of the fourth resistor (R11), and the other end of the fourth resistor (R11) is grounded through the first electrolytic capacitor (C6). The base of the fourth transistor (Q7) is also electrically connected to the output terminal of the power amplifier tube through the fifth resistor (R15). The collectors of the first transistor (Q4) and the second transistor (Q6) serve as the output terminals of the differential amplifier circuit, outputting the second lossless audio signal.

4. The volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier according to claim 3, characterized in that, The voltage amplifier circuit includes: a fifth transistor (Q1) and a sixth transistor (Q8); The base of the fifth transistor (Q1) is electrically connected to the collector of the first transistor (Q4), and the base of the sixth transistor (Q8) is electrically connected to the collector of the second transistor (Q6). The emitter of the fifth transistor (Q1) is electrically connected to one end of the first inductor (L1) through the sixth resistor (R4), and the other end of the first inductor (L1) is electrically connected to the positive terminal of the power supply. The emitter of the sixth transistor (Q8) is electrically connected to one end of the second inductor (L2) through the seventh resistor (R20), and the other end of the second inductor (L2) is electrically connected to the negative terminal of the power supply. The collectors of the fifth transistor (Q1) and the sixth transistor (Q8) serve as the output terminals of the voltage amplifier circuit, outputting a third lossless audio signal to the base of the power amplifier driver transistor.

5. The volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier according to claim 1, characterized in that, A full-time amplitude domain pulse-by-pulse bias circuit is used to receive externally input static bias signals; The full-time amplitude domain pulse-by-pulse bias circuit is also used to generate a first comprehensive bias signal based on the static bias signal and the first dynamic bias signal, and to generate a second comprehensive bias signal based on the static bias signal and the second dynamic bias signal, and output the first comprehensive bias signal and the second comprehensive bias signal to the base of the power amplifier driver transistor.

6. The volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier according to claim 5, characterized in that, The full-time amplitude domain pulse-by-pulse bias circuit includes: a reference source, a positive pulse broadening circuit, a negative pulse broadening circuit, a detection and delay circuit, a first electronic switch, a second electronic switch, a subtractor, and an adder. The reference source is electrically connected to the input terminals of the positive pulse broadening circuit and the negative pulse broadening circuit, respectively, to provide a reference voltage to the positive pulse broadening circuit and the negative pulse broadening circuit; The input terminal of the positive pulse broadening circuit is also electrically connected to the output terminal of the opto-bridge isolation circuit, which is used to generate a half-wave audio signal with a negative half-cycle greater than 180° as a second dynamic bias signal based on the delayed audio signal and the reference voltage, and output it to the first electronic switch. The input terminal of the negative pulse broadening circuit is also electrically connected to the output terminal of the opto-bridge isolation circuit, which is used to generate a half-wave audio signal with a positive half-cycle greater than 180° as a first dynamic bias signal based on the delayed audio signal and the reference voltage, and output it to the second electronic switch. The input terminal of the detection and delay circuit is electrically connected to the output terminal of the opto-bridge isolation circuit. The output terminal of the detection and delay circuit is electrically connected to the first electronic switch and the second electronic switch, respectively. The first electronic switch is electrically connected to the subtractor, and the second electronic switch is electrically connected to the adder. Both the subtractor and the adder are electrically connected to a static bias signal generation circuit to receive the static bias signal output by the static bias signal generation circuit. The subtractor generates a second combined bias signal based on the static bias signal and the second dynamic bias signal, and outputs it to the base of the power amplifier driver transistor. The adder generates a first combined bias signal based on the static bias signal and the first dynamic bias signal, and outputs it to the base of the power amplifier driver transistor.

7. The volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier according to claim 6, characterized in that, The detection and delay circuit is used to simultaneously output a high-level signal for a preset duration to the first electronic switch and the second electronic switch when the delayed audio signal is detected to be output by the opto-bridge isolation circuit, so as to turn on the first electronic switch and the second electronic switch; and to simultaneously output a low-level signal to the first electronic switch and the second electronic switch after a preset delay when the delayed audio signal is detected to be lost, so as to turn off the first electronic switch and the second electronic switch.

8. The volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier according to claim 6, characterized in that, The power amplifier driver transistors include: a first driver transistor (Q2) and a second driver transistor (Q9); The base of the first driving transistor (Q2) is electrically connected to the output terminal of the subtractor and the output terminal of the voltage amplifier circuit, respectively. The base of the second driving transistor (Q9) is electrically connected to the output terminal of the adder and the output terminal of the voltage amplifier circuit, respectively. The collector of the first driving transistor (Q2) is electrically connected to the positive terminal of the power supply, and the collector of the second driving transistor (Q9) is electrically connected to the negative terminal of the power supply. The emitter of the first driving transistor (Q2) is electrically connected to the emitter of the second driving transistor (Q9), and the emitters of the first driving transistor (Q2) and the second driving transistor (Q9) are electrically connected to the power amplifier transistor.

9. A volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier according to claim 8, characterized in that, The power amplifier transistors include: a first power amplifier transistor (Q3) and a second power amplifier transistor (Q10); The base of the first power amplifier transistor (Q3) is electrically connected to the emitter of the first driver transistor (Q2), and the base of the second power amplifier transistor (Q10) is electrically connected to the emitter of the second driver transistor (Q9). The collector of the first power amplifier transistor (Q3) is electrically connected to the positive terminal of the power supply, and the collector of the second power amplifier transistor (Q10) is electrically connected to the negative terminal of the power supply. The emitter of the first power amplifier transistor (Q3) is electrically connected to the emitter of the second power amplifier transistor (Q10) through two series-connected eighth resistors (R03) and ninth resistors (R05). The common terminal of the eighth resistor (R03) and the ninth resistor (R05) serves as the output terminal of the power amplifier transistor.

10. A volume-controlled, full-time amplitude-domain biased, end-link lossless Class A audio power amplifier according to claim 5, characterized in that, The static bias signal is used to control the static current of the power amplifier tube, and the static current is between 400mA and 600mA.

Images