Class H Push-Pull Amplifier Rail Balancing for Symmetrical Output
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Solution Overview
Problem
Push-pull linear hybrid class H audio amplifiers face poor cross regulation between positive and negative power supply rails due to imperfect coupling and unequal loading, limiting the maximum symmetrical voltage that can be reproduced.
Innovation Solution
An audio amplifier design that includes a power supply control circuit generating a control voltage based on the smaller of the positive and negative power supply rails, using an absolute value block, envelope detector, comparator circuit, and differential amplifier to regulate and balance the power supply rails, along with active switching and voltage clamping devices to maintain balanced voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional feedback loops regulate the total voltage or individual power supply rails, then cross regulation compensation is provided, but the maximum symmetrical voltage that can be reproduced is limited due to power rail imbalance
Solution Approach 1:
The patent implements dynamic load balancing by continuously monitoring the voltages of positive and negative power supply rails and actively switching connections to equalize them. The system dynamically adjusts which power source supplies which rail based on real-time voltage measurements, ensuring both rails maintain equal magnitude voltages throughout operation, thereby enabling full utilization of the maximum symmetrical voltage output capability.
2Adaptability or versatility
If split power supplies are used to provide positive and negative power supply rails, then push-pull linear hybrid class H audio amplification is enabled, but poor cross regulation occurs when power sources are unequally loaded
Solution Approach 1:
The patent employs feedback mechanisms by continuously monitoring the voltages of both positive and negative power supply rails through voltage detection circuits. Based on these feedback signals, the control logic determines which rail has lower voltage and switches the power source connections accordingly, actively balancing the voltages. This closed-loop feedback system ensures reliable cross regulation even when power sources are unequally loaded, maintaining the integrity of the push-pull linear hybrid class H amplification operation.
3Power
If one power source is heavily loaded while the other is lightly loaded, then power supply rails are not produced at the same magnitude, but traditional regulation methods cannot simultaneously optimize both rails
Solution Approach 1:
The patent applies asymmetry principle by intentionally allowing the system to operate in an asymmetric state where different power sources may be connected to different rails based on their loading conditions. The control system accepts and adapts to the asymmetric loading scenario by dynamically switching connections to achieve symmetric output voltages. This approach enables the system to handle unequal loading conditions effectively while maintaining precise voltage symmetry at the output rails.
Data Source
AI summary
Several push-pull linear hybrid class H amplifiers are disclosed. A split power rail provides a positive supply rail and a negative supply rail in response to a power supply control voltage. A push-pull amplifier stage is powered by the positive and negative supply rails. The amplifier stage receives an input signal and provides a corresponding amplified output signal. A power supply control circuit provides the power supply control voltage in response to the smaller of the positive and negative supply rails, and the input signal.