Procedimiento de calibración para la medida de dispositivos a temperaturas criogénicas: aplicación al diseño de amplificadores de microondas

This work presents a calibration procedure based on the LRL (Line-Reflect-Line) technique which corrects the drift errors of the network analyzer when the calibration process involves several thermal cycles for cooling the different standards taking long time to finish the measurement process in a cryogenic system. This procedure requires to calibrate each time outside the cryostat before measuring the standards and finally to apply a LRL de-embedding routine to obtain the DUT S-parameters. This technique, especially suitable for in-fixture devices in a cryogenic environment, is applied for measuring the S-parameters of an E-pHEMT device operating at 40 K from 0.4 to 3.2 GHz as a starting point for designing an amplifier in this band. Measurements of S-parameters, using the proposed procedure, of this amplifier at 40 K are presented.