Analysis of mm-Wave Detection with AlGaN/GaN HEMTs by means of Measurements and Physical and Equivalent Circuit Models

The responsivity of microwave zero-bias detectors based on GaN high electron mobility transistors (HEMTs) is measured up to 67 GHz and compared with Monte Carlo (MC) simulations. In addition, a predictive analytical closed-box model based on the measurement (or MC calculation) of the I-V curves and the S-parameters of the devices is shown to replicate the zero-bias current responsivity. The extraction of the HEMT Small-Signal Equivalent Circuit (SSEC) is also exploited to evaluate the responsivity with such closed-form expression. The comparison of the results provided by this approach with the values obtained directly from experiments and MC simulations allows not only to predict the response of the devices at frequencies above the reach of the measurements, but also to identify the physical origin of the detection and the contribution of the different SSEC elements.