Improving the Environmental Temperature Adaptability of an Electric Temperature Measurement Subsystem by Matching Temperature Coefficients of Substitutable Resistors

The electrical temperature measurement subsystem in space gravitational wave detectors requires micro-Kelvin precision in the submillihertz band. However, the low-frequency stability of the measurement circuit, excluding the sensor, is susceptible to environmental temperature fluctuations, closely related to the residual temperature coefficient of the circuit. This paper proposes a method to minimize the residual temperature coefficient for a thermistor-based temperature measurement , enabling the circuit to be mounted on surfaces with less stringent thermal stability requirements. Through extensive testing of resistors with the same nominal resistance, a best-matched pair is selected to compensate for the residual temperature coefficient by replacing two gain resistors in the low-pass filter. Our assessment demonstrates that this matching and replacement process reduces the residual temperature coefficient of the circuit from -0.135 mV K-1 to -0.027 mV K-1, resulting in a significant five-fold improvement in the subsystem's adaptability to environmental temperatures within the specified frequency band. This method contributes to the development of measurement subsystems that meet stringent stability requirements.