Abstract

The modelling and test of a single stage and a two-stage monolithic millimetre-wave (Ka-Band) pseudomorphic HEMT feedback amplifier is reported. The amplifiers used 0.25µm x 120µm devices and were processed on 200µm thick GaAs wafers. The PHEMT s-parameters were measured on-wafer to 40GHz in conjunction with on-wafer Line-Reflect-Line (LRL) calibration standards, which are described. The amplifier modelling approach combined a device equivalent circuit model with a fullwave analysis of the microstrip features and selected measurement-based foundry models. Measured and fitted data are compared for the PHEMT device and for the amplifiers. A single stage feedback amplifier gain of 7.8dB was measured at 33.8GHz and a two-stage feedback amplifier gain of 13.2dB ± 0.4dB from 28.6GHz to 37.9GHz. Both measurements were in good agreement with simulations. The on-wafer measured noise figure of the two stage amplifier was 3.4dB at 35GHz.