Correcting impedance measurements for background parasitics to characterize circuit components in cryogenic environments

TL;DR

This paper introduces an in situ correction method for impedance measurements in cryogenic environments, enabling accurate characterization of circuit components despite parasitic background effects.

Contribution

The authors present a simple experimental procedure and analysis model that corrects parasitic background impedance, improving measurement accuracy of passive components at cryogenic temperatures.

Findings

Measured a 20x capacitance drop in ceramic capacitors at cryogenic temperatures.

Successfully characterized thin-film capacitors and resistors at millikelvin temperatures.

Extended the effective accuracy of a standard LCR meter beyond manufacturer specifications.

Abstract

Predictable circuit response is a critical prerequisite for accurate electronic measurements. We describe a powerful, yet straightforward, experimental method and analysis model that utilizes an affordable LCR meter in conjunction with an in situ parasitic impedance background correction procedure to measure the temperature-dependent impedance (magnitude and phase) of individual passive circuit elements mounted in a cryostat. We show how the model unambiguously identified a 20x drop in capacitance for 22 microF 5XR multilayer ceramic capacitors cooled from 300 K to 360 mK in an environment with parasitic capacitance of order 300 pF. The same experimental procedure, based on a simple two-wire measurement, was also used to successfully measure 10 pF and 22 pF thin-film capacitors and 100 MOhm thick-film resistors. The results showed that the resistor values increased by up to an order of magnitude when the devices were cooled from 300 K to 360 mK. Most importantly, the simple data acquisition method and robust analysis model were shown to effectively extend the accuracy of a simple benchtop LCR meter beyond its manufacturer-guaranteed values for a wide range of measurement frequencies.