Bootstrap Circuit Leakage Compensation in Class-D Amplifiers
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Solution Overview
Problem
Conventional voltage converters and class-D amplifiers face issues with loop breakage due to output capacitor leakage, where the output capacitor voltage is consumed by pre-drivers, leading to false operations.
Innovation Solution
A voltage converter and class-D amplifier design incorporating a bootstrap circuit with an error amplifier, detection circuit, power limiting circuit, and charging circuit to detect output voltage and clamp it within a specific range, generating a charging signal to charge the output capacitor without directly lowering the voltage, thus preventing loop breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output capacitor voltage is directly pulled down to compensate leakage, then the leakage compensation is achieved, but the output voltage stability deteriorates and loop breakage occurs
Solution Approach 1:
The patent introduces a bootstrap circuit as an intermediary mechanism to compensate output capacitor leakage. Instead of directly pulling down the output voltage, the bootstrap circuit charges the output capacitor through a separate path controlled by the detection circuit and charging control circuit, thus eliminating the harmful direct connection that causes loop breakage while still achieving leakage compensation
Solution Approach 2:
The patent implements a feedback mechanism where the detection circuit continuously monitors the output voltage of the output capacitor and feeds this information to the charging control circuit. This feedback loop enables the system to automatically detect when charging is needed and control the charging circuit accordingly, maintaining output voltage stability while compensating for leakage without causing loop breakage
2Loss of energy
If the output capacitor voltage is monitored and directly adjusted to compensate leakage, then the leakage compensation is achieved, but the system stability deteriorates due to loop breakage
Solution Approach 1:
The patent segments the voltage compensation function into separate modules: the detection circuit monitors output voltage, the charging control circuit processes the detection signal and generates control signals, and the charging circuit executes the charging operation. This segmentation isolates the compensation mechanism from the main output voltage regulation loop, preventing loop breakage while achieving leakage compensation and maintaining system stability
Solution Approach 2:
The bootstrap circuit serves as an intermediary that provides an alternative charging path for the output capacitor. This intermediary mechanism allows leakage compensation to occur through a controlled charging process rather than direct voltage adjustment, thereby maintaining system stability while compensating for energy loss
Data Source
AI summary
A voltage converter comprising: a bootstrap circuit, comprising an output capacitor, an error amplifier, a charging control circuit and a charging circuit. The charging control circuit comprises: a detection circuit, configured to detect an output voltage of the output capacitor to generate a detection signal; and a power limiting circuit, configured to clamp an output voltage of the error amplifier to a specific range based on the detection signal. The charging circuit is configured to generate a charging signal according the output voltage of the error amplifier to the bootstrap circuit, to charge the output capacitor.