Audio Amplifier Loop Switching to Reduce Power-On Pop Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio amplifier circuits generate pop noises during power supply changes, cutting off, or operations, causing uncomfortable hearing experiences for users.
Innovation Solution
An audio amplifier circuit design incorporating a pulse width modulation circuit, an auxiliary loop circuit, and a main loop circuit, where the auxiliary loop circuit adjusts resistance and current values to control the main loop circuit's state, reducing pop noises by gradual operation and switching steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the audio amplifier circuit directly switches power supply or performs operations, then the response speed is fast, but pop noises are generated causing uncomfortable hearing experience
Solution Approach 1:
The auxiliary loop circuit is activated before the main loop circuit to pre-adjust the output signal and prepare the system for upcoming power supply changes or operations. This preliminary action ensures that when the main circuit switches, the output already follows the input signal, preventing pop noises while maintaining fast response.
Solution Approach 2:
The auxiliary loop circuit acts as an intermediary between the power supply/main loop and the output. It mediates the transition by gradually adjusting the output signal during switching operations, eliminating sudden voltage changes that cause pop noises while preserving the overall fast response capability of the amplifier.
2Speed
If the auxiliary loop circuit and main loop circuit operate simultaneously with abrupt switching, then the circuit response is fast, but sudden voltage changes occur causing pop noises
Solution Approach 1:
The circuit dynamically adjusts the operation modes of the auxiliary and main loop circuits based on real-time conditions. During power supply changes, the auxiliary loop is activated first with appropriate resistance and current values, then the main loop is gradually engaged. This dynamic switching strategy maintains voltage stability while preserving fast circuit response.
Solution Approach 2:
The patent changes key parameters (resistance values and current values) of both auxiliary and main loop circuits during operation. By adjusting these parameters in a controlled sequence - increasing auxiliary loop current while decreasing main loop current during transitions - the system achieves smooth voltage transitions without pop noises, maintaining both speed and stability.
3Use of energy by moving object
If the main loop circuit is activated without auxiliary loop preparation, then the power supply efficiency is high, but pop noises are generated during switching
Solution Approach 1:
Before activating the main loop circuit for efficient power supply operation, the auxiliary loop circuit is activated in advance to pre-adjust the output signal. This preliminary preparation ensures that when the main loop subsequently switches on for efficient operation, the system is already in a stable state, preventing pop noises while maintaining power supply efficiency.
Solution Approach 2:
The auxiliary loop circuit maintains continuous operation during transitions to ensure the output signal continuously follows the input signal without interruption or sudden changes. This continuous adjustment bridges the gap during switching operations, eliminating pop noises while allowing the main loop to efficiently supply power when activated.
Data Source
AI summary
Audio amplifier circuit includes a pulse width modulation circuit, an auxiliary loop circuit corresponding to a first variable resistance value and a first variable current value, and a main loop circuit corresponding to a second variable resistance value and a second variable current value. Main loop circuit is coupled between a second node, an output terminal, and a first node. Under a condition that auxiliary loop circuit and main loop circuit are turned on, second variable resistance value is decreased and second variable current value is increased after auxiliary loop circuit enters into a first control state, such that main loop circuit enters into a second control state. First variable resistance value is increased and first variable current value is decreased after main loop circuit enters into second control state, such that auxiliary loop circuit is out of first control state.