A DSP controlled low power consumption instant-on constant voltage power amplifier system

Abstract

The application discloses a DSP-controlled low-power instant-on constant-voltage power amplifier system, which is suitable for public broadcasting and comprises a data communication module, a DSP processing module, a standby module and a power amplification module. The data communication module comprises a receiving circuit, an audio isolation transformer, a signal detection circuit and a signal transmission circuit, the receiving circuit receives external sound source signals and outputs the signals to the DSP processing module. The input of the DSP processing module is the output of the data communication module and the judgment output of the standby module, and the DSP processing module outputs after signal processing and is connected with the power amplification module. The output of the signal detection circuit and the output end of the power amplification module are connected with the standby module, and the standby module controls the start and stop of the power amplification module and judges the load. The power amplification module receives the signals processed by the DSP processing module, amplifies the signals to a power supply rail according to the control of the standby module and directly connects with a load output. The application utilizes the cooperation of DSP and a micro control unit to process signals and control the system, and is more flexible and responds quickly.

Description

Technical Field

[0001] This invention relates to the field of constant voltage power amplifiers, and more specifically to a DSP-controlled, low-power, ready-to-use constant voltage power amplifier system. Background Technology

[0002] In existing technologies, due to the use of Class D modulation amplification technology, the distortion and noise generated by ordinary constant-voltage power amplifiers during normal amplification are almost inaudible. However, in comparison, in standby mode, due to the inherent layout and topology of the electronic circuitry, background noise is generated, and this cannot be fundamentally improved, inevitably resulting in standby noise that affects practical use. Constant-voltage power amplifiers operate both continuously and intermittently, typically requiring tens of hours of operation, but without a continuous audio source. When no audio source is connected, the constant-voltage power amplifier remains in standby mode for extended periods, consuming a considerable amount of power.

[0003] Since constant voltage power amplifiers are mainly used for public broadcasting, they have high requirements for being ready to use immediately. Existing constant voltage power amplifiers for broadcasting require a startup time, which may result in missing words when they are ready to use immediately. This may prevent the recipients from receiving all the broadcast information, and in an emergency, it may even threaten the life and property safety of the recipients.

[0004] With the development of technology, the integration of digital audio processors will become increasingly higher in the future. Analog designs alone will no longer be able to meet the various usage requirements and functional needs of users for audio products. Therefore, it will become very necessary to embed DSP chips into audio products.

[0005] Therefore, in order to reduce the energy consumption of constant voltage power amplifiers, improve their performance, and keep pace with technological development trends, it is necessary to provide a DSP-controlled, low-power, ready-to-use constant voltage power amplifier. Summary of the Invention

[0006] In view of the above problems, the present invention provides a fully isolated, low-power, ready-to-use constant voltage power amplifier system with embedded DSP chip control.

[0007] This invention discloses a DSP-controlled, low-power, ready-to-use constant-voltage power amplifier system suitable for public transportation and public address systems. It includes a data communication module, a DSP processing module, a standby module, and a power amplifier module. The data communication module includes a receiving circuit, an audio isolation transformer, a signal detection circuit, and a signal transmission circuit. The receiving circuit receives external audio signals, isolates and transmits them, and then outputs them to the DSP processing module. The input terminal of the DSP processing module is connected to the output of the data communication module and one output terminal of the standby module to process the audio signal. Its output terminal is connected to the power amplifier module. The standby module is connected to the output signal of the signal detection circuit and the output terminal of the power amplifier module, controlling the start / stop of the power amplifier module and performing load detection. The power amplifier module receives the signal processed by the DSP processing module, amplifies it to the power rail via an internal coupling circuit, and then, under the control of the standby module, directly connects to the load output without the need for an output step-up transformer.

[0008] The data communication module includes a receiving circuit, an audio isolation transformer, a signal detection circuit, and a signal transmission circuit. It receives external audio source signals, performs input-output isolation, and detects the presence of the audio source. The receiving circuit includes an analog receiving port and a Bluetooth module. The analog receiving port is wired, and the audio source is connected to the analog receiving port via a transmission line. The Bluetooth module, after pairing with the audio source, enables wireless Bluetooth transmission. The output of the analog receiving port is connected to the primary winding of the audio isolation transformer, and the secondary winding is connected to the signal transmission circuit and the signal detection circuit. The signal detection circuit includes two operational amplifier circuits. The non-inverting inputs of the two operational amplifier circuits are respectively connected to the output of the audio isolation transformer and the output of the Bluetooth module. Both operational amplifier circuits use non-inverting amplification, and their outputs are connected to the same input of the standby module via a diode. The signal transmission circuit includes two operational amplifier circuits. The non-inverting inputs of the two operational amplifier circuits are respectively connected to the output of the audio isolation transformer and the output of the Bluetooth module. Both operational amplifier circuits use non-inverting amplification, and their outputs are connected to two input pins of the DSP processing module.

[0009] The DSP processing module includes a dedicated audio DSP chip and its supporting circuitry, used for digital processing of the input audio source and system startup control. The processing module within the DSP chip is mainly divided into a gain control module and a switching module. The gain control module is a noise threshold with gain control, used to actively reduce background noise. It first performs analog-to-digital conversion on the input signal, then performs signal detection, and automatically adjusts the DSP's internal gain based on the signal amplitude and duration: setting a minimum threshold V1 for the audio source signal and a minimum duration threshold T1, prioritizing gain based on signal amplitude; that is, when the signal amplitude exceeds the minimum threshold V1, the default amplification gain is used regardless of the duration; when the signal amplitude is below the minimum threshold V1, if the duration exceeds the minimum threshold T1, the default gain is reduced. The digital audio source signal processed by the gain control module undergoes general processing such as dynamic compression, noise suppression, and filtering, then undergoes digital-to-analog conversion and is connected to the input of the power amplifier module through the output of the DSP chip. The switching module is used for switching between constant voltage and constant impedance modes. Upon power-up, the signal gain of the DSP processing module defaults to the constant voltage mode gain. Immediately upon system power-up, the DSP chip generates a test signal with a frequency greater than 18kHz, an amplitude greater than the minimum threshold V1, and less than the maximum output of the audio DSP signal. The standby module sends the load judgment result to the DSP processing module. If the judgment result indicates a constant impedance load, the DSP processing module reduces its internal gain; if the judgment result indicates a constant voltage load, the DSP processing module maintains its gain unchanged.

[0010] The standby module includes a microcontroller unit and its associated circuitry, used to control the mute, standby, and load identification modes of the power amplification system. Since the microcontroller unit has a shorter trigger time and lower power consumption than a DSP, these functions are implemented using a separate microcontroller unit. The input terminal of the microcontroller unit is connected to the output signal of the signal detection circuit, detecting the amplitude and duration of the signal, and presetting a minimum threshold V2, a mute threshold T2, and a standby threshold T3.<V1、T3> When T2 > T1, control commands are sent preferentially based on signal amplitude. If the signal amplitude is less than the minimum threshold V2 and the duration exceeds the mute threshold T2 but is less than the standby threshold T3, the microcontroller sends a mute command to the power amplifier module, shutting off its input. If the signal amplitude is less than the minimum threshold V2 and the duration exceeds the standby threshold T3, the microcontroller sends a standby command to the power amplifier module, controlling it to enter standby mode. When the power amplifier module is in mute or standby mode, if the microcontroller detects a signal amplitude greater than the minimum threshold V2, regardless of the duration, it sends a command to the power amplifier module to restore normal operation, i.e., de-mute or de-standby. When the system powers on, the DSP processing module generates a test signal. The microcontroller detects the voltage and current at the output of the power amplifier module, calculates and determines the load type, and sends the result to the DSP processing module. If the load is determined to be a constant resistance load, a current limiting switching signal is simultaneously sent to the power amplifier module.

[0011] The power amplification module includes a coupling circuit and a power amplification circuit, used to receive and amplify the signal processed by the DSP processing module, and connect it to the load output. The coupling circuit uses RC coupling to couple the output signal of the DSP processing module to the input terminal of the power amplification circuit. The power amplification circuit includes a pulse width modulation circuit, a power stage circuit, a filter circuit, and a current limiting circuit. The pulse width modulation circuit modulates the input signal to generate a PWM signal with varying duty cycle; the power stage circuit uses a driver chip to drive the power stage MOSFET switch according to the PWM signal to generate a PWM signal amplified to the power rail; the filter circuit filters out high-frequency components in the PWM signal amplified to the power rail, restoring the original input signal, and thus connecting it to the load output; the current limiting circuit uses a programmable gain amplifier to adjust the current limiting value. It defaults to constant voltage current limiting upon power-up. If the microcontroller determines that the load is a constant resistance load, it sends a switching command to the programmable gain amplifier to increase the current limiting value.

[0012] Preferably, when the power amplifier module is in a mute state, the microcontroller unit immediately sends a command to the power amplifier module to de-mute once it detects that the signal amplitude is greater than the minimum threshold V2; when the power amplifier module is in a standby state, the microcontroller unit needs to delay before sending a command to de-standby once it detects that the signal amplitude is greater than the minimum threshold V2, and the delay time is the time constant of the coupling circuit using RC coupling.

[0013] This invention discloses a DSP-controlled, low-power, ready-to-use constant-voltage power amplifier system. When there is no audio input, the DSP and microcontroller unit work together to reduce noise floor and power consumption in stages through gain reduction, mute, and standby modes, thereby increasing reliability. The microcontroller unit controls the power amplifier's turn-on sequence during standby, effectively preventing "missing words" and eliminating popping noise during operation. The system can be switched to constant-impedance mode for use with a wider range of loads. The DSP-based signal processing is more flexible and compact than analog signal processing circuits, and its functionality can be expanded as needed, providing users with more possibilities.

[0014] To make the above description of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic block diagram of a DSP-controlled, low-power, ready-to-use constant-voltage power amplifier system according to the present invention. Figure 2 This is a circuit diagram of the data communication module of a DSP-controlled low-power, ready-to-use constant-voltage power amplifier system according to the present invention. Figure 3 This is a circuit diagram of the power amplifier circuit in the power amplifier module of a DSP-controlled low-power, ready-to-use constant-voltage power amplifier system according to the present invention. Number in the picture: 10: Data communication module; 20: DSP processing module; 30: Standby module; 40: Power amplifier module; 101: Receiver circuit; 102: Audio isolation transformer; 103: Signal detection circuit and signal transmission circuit; 1031: Signal detection circuit; 1032: Signal transmission circuit; 401: Power amplifier circuit. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0018] Please see Figure 1 This is a schematic block diagram of a DSP-controlled low-power, ready-to-use constant-voltage power amplifier system according to the present invention. It includes a data communication module 10, a DSP processing module 20, a standby module 30, and a power amplifier module 40. The data communication module 10 includes a receiving circuit 101, an audio isolation transformer 102, a signal detection circuit, and a signal transmission circuit 103. The receiving circuit 101 receives external audio source signals, isolates and transmits them, and then outputs them to the DSP processing module 20. The input terminal of the DSP processing module 20 is connected to the output terminal of the data communication module 10 and the output terminal of the standby module 30, performing signal processing on the audio source and controlling the start and stop of the system. Its output terminal is connected to the power amplifier module 40. The standby module 30 is connected to the output signal of the signal detection circuit and the detection signal at the output terminal of the power amplifier module 40, controlling the start and stop of the power amplifier module 40. The power amplifier module 40 receives the signal processed by the DSP processing module 20, and after passing through an internal coupling circuit, amplifies the signal to the power rail according to the control of the standby module 30, directly connecting to the load output without the need for an output step-up transformer.

[0019] Please see Figure 2This is a circuit diagram of the data communication module 10 of a DSP-controlled low-power, ready-to-use constant-voltage power amplifier system according to the present invention. The data communication module 10 includes a receiving circuit, an audio isolation transformer 102, a signal detection circuit 1031, and a signal transmission circuit 1032. It is used to receive external audio source signals and perform input-output isolation, and to detect the presence of the audio source. The receiving circuit includes an analog receiving port 1011 and a Bluetooth module 1012. The analog receiving port 1011 is a wired connection; the audio source is connected to the analog receiving port 1011 via a transmission line. The Bluetooth module 1012 can perform wireless Bluetooth transmission after pairing with the audio source. The output of the analog receiving port 1011 is connected to the primary side of the audio isolation transformer 102, and the secondary side is connected to the signal transmission circuit 1032 and the signal detection circuit 1031. The signal detection circuit 1031 includes two operational amplifier circuits A3 and A4. The non-inverting inputs of A3 and A4 are connected to the output of the audio isolation transformer 102 and the output of the Bluetooth module 1012, respectively. Both A3 and A4 use non-inverting amplification, and their outputs are connected to the same input terminal of the standby module 30 after passing through a diode. The signal transmission circuit 1032 includes two operational amplifier circuits A1 and A2. The non-inverting inputs of A1 and A2 are connected to the output of the audio isolation transformer 102 and the output of the Bluetooth module 1012, respectively. Both A1 and A2 use non-inverting amplification, and their outputs are connected to two input pins of the DSP processing module 20.

[0020] Please see Figure 3 This is a circuit diagram of the power amplifier circuit in the power amplifier module of a DSP-controlled low-power, ready-to-use constant-voltage power amplifier system according to the present invention. The power amplifier circuit 402 includes a pulse width modulation circuit 4021, a power stage circuit 4022, a filter circuit 4023, and a programmable gain amplifier 4024. Resistor R1 is used to detect the output current. The programmable gain amplifier 4024 is used to switch the current limiting value according to the instructions of the standby module 30. The default current limiting value is the constant-voltage mode current limiting value, controlled by the switching instructions of the standby module 30. If it is a constant-resistance load, the current limiting value is increased.

[0021] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A DSP controlled low power consumption PDA (plug and display audio) constant voltage power amplifier system, characterized by, It includes a data communication module, a DSP processing module, a standby module, and a power amplifier module; The data communication module includes a receiving circuit, an audio isolation transformer, a signal detection circuit, and a signal transmission circuit. The receiving circuit receives external audio source signals, and after isolation and transmission processing, outputs them to the DSP processing module. The input terminal of the DSP processing module is connected to the output of the data communication module and one output terminal of the standby module to perform signal processing on the audio source, and the output terminal is connected to the power amplifier module. The standby module is connected to the output signal of the signal detection circuit and the output terminal of the power amplifier module, and controls the start and stop of the power amplifier module and performs load judgment. The power amplifier module receives the signal processed by the DSP processing module, and after passing through the internal coupling circuit, amplifies the signal to the power rail according to the control of the standby module, so that it can be directly connected to the load output without the need for an output step-up transformer. The DSP processing module includes a dedicated audio DSP chip and its supporting circuitry; the processing modules within the DSP chip are mainly divided into a gain control module and a switching module. The gain control module is a noise threshold with gain control. It first performs analog-to-digital conversion on the input signal, then performs signal detection. A minimum threshold V1 and a minimum duration threshold T1 are preset for the audio source signal. Gain is prioritized based on signal amplitude; that is, when the signal amplitude exceeds the minimum threshold V1, the default amplification gain is used regardless of the duration. When the signal amplitude is below the minimum threshold V1, if the duration exceeds the minimum threshold T1, the default gain is reduced. The digital audio source signal processed by the gain control module undergoes dynamic compression, noise suppression, and filtering, followed by digital-to-analog conversion, and is connected to the input of the power amplifier module through the output of the DSP chip. The switching module is used for switching between constant voltage and constant impedance modes. When powered on, the signal gain of the DSP processing module defaults to the gain of constant voltage mode. When the system is powered on, the DSP chip immediately generates a test signal with a frequency greater than 18kHz, an amplitude greater than the minimum threshold V1, and less than the maximum output of the audio DSP signal. The standby module sends the load judgment result to the DSP processing module. If the judgment result is a constant impedance load, the DSP processing module reduces its internal gain; if the judgment result is a constant voltage load, the DSP processing module maintains its gain unchanged.

2. A DSP controlled low power consumption PDA power amplifier system as recited in claim 1, wherein, The data communication module includes a receiving circuit, an audio isolation transformer, a signal detection circuit, and a signal transmission circuit; The receiving circuit includes an analog receiving port and a Bluetooth module. The analog receiving interface is a wired connection, and the audio source is connected to the analog receiving port via a transmission line. The Bluetooth module can perform wireless Bluetooth transmission after being paired with the audio source. The output of the analog receiving port is connected to the primary side of the audio isolation transformer, and the secondary side is connected to the signal transmission circuit and the signal detection circuit. The signal detection circuit includes two operational amplifier circuits. The non-inverting input terminals of the two operational amplifier circuits are respectively connected to the output of the audio isolation transformer and the output of the Bluetooth module. Both operational amplifier circuits use non-inverting amplification, and their outputs are connected to the same input terminal of the standby module after passing through a diode. The signal transmission circuit includes two operational amplifier circuits. The non-inverting input terminals of the two operational amplifier circuits are respectively connected to the output of the audio isolation transformer and the output of the Bluetooth module. Both operational amplifier circuits use non-inverting amplification, and the outputs of the operational amplifiers are connected to the two input pins of the DSP processing module.

3. A DSP controlled low power consumption PDA power amplifier system as recited in claim 1, wherein, The standby module includes a microcontroller unit and its supporting circuitry; the input terminal of the microcontroller unit is connected to the output signal of the signal detection circuit, detecting the amplitude and duration of the signal, and preset a minimum threshold V2, a mute threshold T2, and a standby threshold T3, where V2...<V1、T3> If T2 > T1, control commands are sent based on the signal amplitude first. When the signal amplitude is less than the minimum threshold V2 and the duration exceeds the mute threshold T2 but is less than the standby threshold T3, the microcontroller sends a mute command to the power amplifier module to turn off the input terminal of the power amplifier module. When the signal amplitude is less than the minimum threshold V2 and the duration exceeds the standby threshold T3, the microcontroller sends a standby command to the power amplifier module to control the power amplifier module to enter the standby state. When the power amplifier module is in a mute or standby state, if the microcontroller detects that the amplitude of the signal is greater than the minimum threshold V2, regardless of how short the duration is, it sends a command to the power amplifier module to resume normal operation, immediately sends a command to the power amplifier module to release the mute state, or sends a command to the power amplifier module to release the standby state after a delay. The delay time is determined by the RC time constant of the coupling circuit in the power amplifier module. When the system is powered on, the DSP processing module generates a test signal. The microcontroller detects the voltage and current at the output of the power amplifier module, performs calculations to determine the type of load, and sends the determination result to the DSP processing module. If the load is determined to be a constant resistance load, a current limiting switching signal is sent to the power amplifier module at the same time.

4. A DSP controlled low power consumption PDA power amplifier system as recited in claim 1, wherein, The power amplifier module includes a coupling circuit and a power amplifier circuit, and is connected to the load output; The coupling circuit uses a resistor-capacitor coupling method to couple the output signal of the DSP processing module to the input terminal of the power amplifier circuit; The power amplifier circuit includes a pulse width modulation circuit, a power stage circuit, a filter circuit, and a current limiting circuit. The pulse width modulation circuit modulates the input signal to generate a PWM signal with varying duty cycle. The power stage circuit is driven by a driver chip to switch the power stage MOSFET according to the PWM signal, thereby generating a PWM signal amplified to the power rail. The filter circuit filters out high-frequency components in the PWM signal amplified to the power rail, restoring the original input signal, and then connects to the load output. The current limiting circuit uses a programmable gain amplifier to adjust the current limiting value. It defaults to constant voltage current limiting when powered on. If the microcontroller determines that the load is a constant resistance load, it sends a switching command to the programmable gain amplifier to increase the current limiting value.

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