Ultrastable and Low-Noise Self-Compensation Method for Circuit Thermal Drift of Eddy Current Sensors Based on Analog Multiplier

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This article proposes a self-temperature compensation method based on an analog multiplier, which reduces the circuit thermal drift by more than an order of magnitude. An ac bridge eddy current sensor (ECS) is used as an example to analyze the thermal drift of the circuit in detail, and the basic principle of the compensation method is expounded. A high-precision ECS prototype is manufactured and tested. Results show that the temperature coefficient of the circuit in the prototype is decreased from 243 to 5 ppm/°C with this technique. This self-compensation method is simple, effective, and universal. Furthermore, this technique has a unique advantage for high-bandwidth and high-precision sensors and can work efficiently in complex and harsh temperature environments.