Differential Amplifier Drift Correction for Common-Mode Offset
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Solution Overview
Problem
Amplifier circuits with differential inputs face challenges in maintaining precision due to offset errors induced by common-mode voltages, which can drift with temperature, exceeding error budgets across specified operating ranges.
Innovation Solution
The implementation of a temperature drift correction scheme using first and second drift correction signal generators, with different temperature coefficients, to compensate for residual offset errors across a range of temperatures, coupled through an injection circuit to the amplifier circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single-temperature offset compensation is performed, then the offset voltage is reduced at that specific temperature, but temperature drift causes residual offset errors across the operating temperature range
Solution Approach 1:
The temperature drift correction is segmented into multiple independent signal paths, each with different temperature coefficients. The first drift correction signal path and second drift correction signal path are separated and can be independently adjusted, allowing precise compensation at multiple temperature points rather than a single combined correction
Solution Approach 2:
The invention changes the temperature coefficient parameter of the drift correction signals by providing multiple signal paths with different temperature coefficients. This allows the system to adapt the correction characteristics to match the actual drift behavior across the temperature range, improving both precision and stability
2Stability of the object's composition
If drift correction signals with different temperature coefficients are used, then temperature drift across the operating range is corrected, but device complexity increases due to multiple signal generator circuits
Solution Approach 1:
The drift correction signal generator is designed with multi-functionality, where a single integrated circuit performs the functions of multiple signal generators with different temperature coefficients. The circuit can selectively activate different correction paths based on temperature conditions, reducing overall device complexity while maintaining drift correction capability
Solution Approach 2:
Multiple drift correction signal paths with different temperature coefficients are merged into a single integrated drift correction circuit. This consolidation reduces the number of discrete components and simplifies the overall device architecture while preserving the ability to correct temperature drift across the operating range
Data Source
AI summary
An amplifier circuit can have a differential input. A common-mode signal present at the differential input can induce an offset voltage at an output of the amplifier circuit. A compensation can be performed to reduce or eliminate such an offset, such as at a first temperature. Circuits and techniques for drift correction can be performed, such as to correct for residual offset error across an entirety of a specified operation temperature range. In an example, first and second drift correction signal generator circuits can be used, such as to provide signals proportional to a common mode voltage, but having different temperature coefficients.