Common-Mode Voltage Control in Self-Boosting Push-Pull Amplifiers
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Solution Overview
Problem
Self-boosting push-pull amplifiers face excessive component stresses due to high common mode voltages and currents, leading to increased thermal losses and reduced reliability, especially when amplifying audio signals with varying crest-factors.
Innovation Solution
A common mode voltage controller dynamically adjusts the gain and duty cycle of input signals to reduce the common mode voltage of self-boosting push-pull amplifiers, maintaining differential mode voltage while minimizing component stresses, by calculating and applying a duty cycle offset based on detected signal levels and supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If self-boosting push pull amplifier operates with high common mode voltage, then differential mode voltage (amplified signal) is maintained, but component stresses and thermal losses increase
Solution Approach 1:
The patent separates the control of common mode voltage from differential mode voltage. The common mode voltage controller independently adjusts the common mode component while the differential mode signal remains intact, allowing selective reduction of harmful common mode voltages without affecting the useful amplified audio signal.
Solution Approach 2:
The patent dynamically changes the common mode voltage parameter in real-time based on the input signal characteristics (crest factor, amplitude). By adjusting the common mode voltage parameter adaptively, the system reduces thermal losses during low-power operation while maintaining sufficient voltage headroom for peak signals.
2Reliability
If common mode voltage is reduced, then thermal losses and component stresses decrease, but amplifier reliability may be compromised
Solution Approach 1:
The common mode voltage controller implements dynamic adjustment of common mode voltage based on real-time signal analysis. The system transitions from static high common mode voltage to dynamic adaptive voltage levels, reducing stress and thermal losses while maintaining reliability through intelligent control rather than fixed conservative design.
Solution Approach 2:
The patent employs feedback mechanisms where the common mode voltage controller continuously monitors the amplifier operation and adjusts common mode voltage accordingly. This closed-loop control ensures that common mode voltage is reduced only when safe, maintaining component reliability while minimizing thermal losses.
3Use of energy by moving object
If duty cycle offset is applied to reduce common mode voltage, then power efficiency improves, but signal accuracy may be affected
Solution Approach 1:
The patent applies asymmetric duty cycle offset adjustment where different offset values are applied to different channels or different time periods based on signal characteristics. This asymmetric control allows optimization of power efficiency for each operating condition while preserving the integrity of the differential mode signal through careful balancing.
Data Source
AI summary
Various implementations include systems for amplifying input signals. In particular implementations, a system includes a common mode voltage controller configured to receive an input signal and output a pair of adjusted signals; a modulator that generates a pair of pulse width modulation (PWM) signals in response to the adjusted signals; and a self-boosting push pull amplifier configured to receive the PWM signals and generate an amplified output, wherein the self-boosting push pull amplifier is configured to generate a differential mode voltage representative of an amplified version of the input signal, wherein the adjusted audio signals generated by the common mode voltage controller include a dynamically adjusted gain and duty cycle offset that causes the self-boosting push pull amplifier to operate with a reduced common mode voltage.