Multilayer planar inductor array based angular position sensor for cryogenic application

The design, development and testing of a cryogenically operated multilayer planar inductor array based eddy current angular position/rotation transducer is claimed. An array of 4 multi-layered coils is used to divide the 360° into four sectors of 90° each. Switching between each of the inductor is done by a cold electronics based multiplexer circuit coupled to an unbuffered inverter LC oscillator. The angular displacement is a function of frequency of cold electronic LC oscillator. The pickup coil forms the inductor of the oscillator which is operated down to 4.2 K and uses thermal cycled stable components. The change in frequency as a function of angular displacement was calibrated at cryogenic temperatures. The developed sensor was found to have good thermal stability, sensitivity and repeatability over the entire cryogenic range.