Improving the environmental temperature adaptability of an electric temperature measurement subsystem by matching temperature coefficients of substitutable resistors

Abstract

The electrical temperature measurement subsystem in space gravitational wave detectors requires micro-Kelvin precision in the sub-millihertz band. However, the low-frequency stability of the measurement circuit, excluding the sensor, is susceptible to environmental temperature fluctuations, closely linked 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 subsystem, 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 backend circuit from -0.135 mV/K to -0.027 mV/K, 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.