Amplifier Mismatch Compensation Using Current Ratio Measurement
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Solution Overview
Problem
Existing methods for measuring component mismatch in audio signal amplifiers, such as Class-D amplifiers, are inaccurate and require extensive additional circuitry, leading to performance degradation due to harmonic distortion.
Innovation Solution
A current ratio measurement engine (CRME) and delta sigma modulator (DSM) system that utilizes existing circuitry to measure and compensate for component mismatch by iteratively changing circuit configurations, calculating adjustment parameters, and reconfiguring the amplifier circuit to improve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods are used to measure component mismatch in audio signal amplifiers, then measurement capability is provided, but measurement accuracy is poor and additional circuitry is required
Solution Approach 1:
The amplifier circuit measures its own component mismatch using its existing operational amplifier and resistor network, without requiring external measurement equipment or additional dedicated measurement circuitry. The circuit leverages its own internal components to perform self-diagnosis and self-characterization.
Solution Approach 2:
The operational amplifier and resistor network serve dual purposes: they function as the core amplification circuit during normal operation and simultaneously serve as the measurement apparatus for characterizing component mismatch. This multi-functionality eliminates the need for separate measurement equipment.
2Measurement precision
If extensive additional circuitry is added to measure component mismatch, then measurement capability is improved, but amplifier performance degrades due to harmonic distortion
Solution Approach 1:
The measurement is performed using the amplifier's own existing components without adding external measurement equipment that could introduce parasitic signals and harmonic distortion. The self-service approach ensures measurement capability while maintaining amplifier performance.
3Manufacturing precision
If component mismatch is measured and compensated, then gain accuracy is improved, but measurement and compensation time increases
Solution Approach 1:
The component mismatch measurements are performed in advance during the manufacturing or initialization phase, and the resulting adjustment parameters are stored in memory. This preliminary characterization allows for rapid compensation during operation without requiring time-consuming real-time measurements.
Solution Approach 2:
The system dynamically switches between different circuit configurations to efficiently extract multiple measurement data points. By iteratively changing the circuit state and collecting measurements, the system achieves comprehensive characterization in a practical timeframe.
Data Source
AI summary
A method and system of compensating for component mismatch are disclosed. An example system comprises an amplifier including a current ratio measurement engine (CRME) and a modulator (DSM). The CRME is configured to obtain measurements for each possible configuration of an amplifier circuit and to pass these measurements to a processor for analysis. In the example system, the measurements are obtained by driving a bias current through two or more circuit elements and measuring the ratio in current between the two or more circuit elements, which is representative of the relative mismatch between the two or more components. The DSM is configured to receive adjustment parameters from the processor and to tune the amplifier circuit according to the adjustment parameters to thereby improve the performance of the amplifier.