Variable-temperature attenuator calibration method for on-wafer microwave noise characterization of low-noise amplifiers

TL;DR

This paper introduces a calibration method for on-wafer microwave noise measurements of cryogenic low-noise amplifiers, improving accuracy by accounting for input loss and temperature gradients through multi-temperature attenuator measurements.

Contribution

A novel calibration technique that simultaneously determines noise temperature and effective noise ratio using multi-temperature attenuator measurements.

Findings

Validated method with InP HEMTs in 4-8 GHz

Enables accurate noise characterization at cryogenic temperatures

Generalizable to other two-port microwave devices

Abstract

Low-noise cryogenic microwave amplifiers are widely used in applications such as radio astronomy and quantum computing. On-wafer noise characterization of cryogenic low-noise transistors is desirable because it facilitates more rapid characterization of devices prior to packaging, but obtaining accurate noise measurements is difficult due to the uncertainty arising from the input loss and temperature gradients prior to the device-under-test (DUT). Here, we report a calibration method that enables the simultaneous determination of the backend noise temperature and effective-noise-ratio at the input plane of the DUT. The method is based on measuring the S-parameters and noise power of a series of attenuators at two or more distinct physical temperatures. We validate our method by measuring the noise temperature of InP HEMTs in 4-8 GHz. The calibration method can be generalized to measure the microwave noise temperature of any two-port device so long as a series of attenuators can be measured at two or more distinct physical temperatures.