De-Pop Amplifier Control for Low THD During Audio Transients
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Solution Overview
Problem
Conventional audio amplifiers face challenges in simultaneously reducing total harmonic distortion (THD) and pop noise, as increasing the driving ability of the OP amplifier worsens pop noise while decreasing it increases THD, making it difficult to achieve both objectives simultaneously.
Innovation Solution
A de-pop circuit comprising an amplifier, comparator, timing control circuit, and signal bypass circuit that adjusts the driving ability of the OP amplifier during transient periods and bypasses the audio output signal to ground, using transient indication signals and reference voltages to control the driving ability and bypass the signal effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the driving ability of the OP amplifier is increased to reduce THD, then the total harmonic distortion decreases, but the pop noise becomes more serious
Solution Approach 1:
The patent applies dynamics by making the driving ability of the OP amplifier adjustable rather than fixed. The controller dynamically changes the driving ability based on the operating state: using high driving ability during normal operation to reduce THD, and switching to low driving ability during transient states (power on/off) to minimize pop noise. This dynamic adaptation resolves the contradiction between reducing THD and minimizing pop noise.
Solution Approach 2:
The patent changes the parameter of driving ability based on different operating conditions. By detecting transient states and adjusting the driving ability parameter accordingly, the system achieves low THD during stable operation while suppressing pop noise during transitions. This parameter change strategy allows the amplifier to optimize performance for different operational phases.
2Object-generated harmful factors
If the driving ability of the OP amplifier is decreased to reduce pop noise, then the pop noise is reduced, but the high-impedance speaker cannot be driven properly so that THD gets greater
Solution Approach 1:
The system dynamically adjusts the driving ability based on real-time detection of operating states. During transient periods when pop noise occurs, the driving ability is reduced. During normal stable operation, the driving ability is increased to properly drive high-impedance speakers and maintain low THD. This dynamic control resolves the contradiction between pop noise reduction and proper speaker driving.
Solution Approach 2:
The controller detects transient states in advance and proactively adjusts the driving ability before pop noise can occur. By anticipating the transient condition and pre-adjusting the amplifier parameters, the system prevents pop noise generation while maintaining optimal performance during subsequent normal operation.
3Device complexity
If a single driving ability setting is used for both low-impedance and high-impedance speakers, then the circuit design is simplified, but the amplifier cannot simultaneously achieve low THD and minimal pop noise
Solution Approach 1:
The patent changes the driving ability parameter based on detected operating conditions rather than using a fixed setting. This allows the single circuit design to adapt to different speaker impedances and operating states, achieving low THD for both low-impedance and high-impedance speakers while maintaining simplicity in the overall circuit architecture.
Solution Approach 2:
The controller provides multi-functionality by enabling the same amplifier circuit to optimally drive both low-impedance and high-impedance speakers through dynamic parameter adjustment. The system universally handles different speaker types and operating conditions without requiring separate circuit designs, achieving both simplicity and high performance.
Data Source
AI summary
A de-pop controller and method thereof are provided. The controller includes an amplifier and a comparator. The amplifier receives and amplifies an audio input signal, and then outputs an audio output signal. The comparator, coupled to the amplifier, receives a transient indication signal. The comparator compares the transient indication signal with a reference voltage, and the comparison result is then applied to control the driving ability of the amplifier for de-popping.