Amplifier Offset Drift Correction With Second-Order Temperature Compensation
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Solution Overview
Problem
Amplifier circuits in integrated circuits are susceptible to offset voltages that include both linear and nonlinear components, which can limit their precision and accuracy, especially under varying temperature conditions.
Innovation Solution
An amplifier circuit with a differential input stage and an offset error correction circuit that generates a second-order error correction signal, including a constant, first-order temperature-dependent, and second-order temperature-dependent components, to reduce both linear and nonlinear offset errors by applying this signal to the differential input stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional amplifier circuit is used, then the circuit is simple in structure, but the offset error includes significant nonlinear portions that reduce measurement precision
Solution Approach 1:
The offset error is segmented into linear and nonlinear portions, and the correction signal is segmented into first-order (linear) and second-order (nonlinear) temperature-dependent components. This segmentation allows targeted correction of each error type using appropriate circuit elements and temperature sensing mechanisms.
Solution Approach 2:
The invention changes the temperature-dependent parameters of the correction signal to match the temperature dependence of the offset error. By generating correction signals with specific first-order and second-order temperature coefficients, the circuit dynamically adjusts the correction amount based on temperature variations, thereby reducing both linear and nonlinear offset errors.
2Reliability
If temperature compensation is applied to reduce offset drift, then the precision is improved, but the device complexity increases due to additional correction circuits
Solution Approach 1:
The correction circuit generates temperature-dependent correction signals in advance based on the sensed temperature, and applies these pre-computed corrections to the differential input stage. This preliminary action prevents the offset error from affecting the measurement outcome, rather than attempting to correct it after the fact.
Solution Approach 2:
A temperature sensing mechanism acts as an intermediary between the actual temperature conditions and the correction signal generation. This intermediary converts temperature information into electrical signals that can be processed by the correction circuit to generate appropriate compensation signals.
Data Source
AI summary
An amplifier circuit comprises a differential input stage configured to receive a differential input signal, wherein the differential input stage is susceptible to an offset error that includes a linear offset error portion and a nonlinear offset error portion; and an offset error correction circuit coupled to the differential input stage and configured to apply a second order error correction signal to the differential input stage to reduce the nonlinear portion of the offset error.