A very-low-power AC bridge for high-resolution remote resistance thermometry

Abstract

The equipment described here was designed to resolve temperature changes of the order of microdegrees within a few seconds, with power dissipation in the thermistor sensor limited to a few microwatts. The requirement arose from an X-ray calorimeter development program, but the equipment described here is suitable for a range of applications where small resistance changes (say 1 part in 2*10⁷) are to be monitored and the measuring bridge may be remote from the sensor, in an uncontrolled environment.