Robustness of GaN on SiC low-noise amplifiers in common source and cascode configurations for X-band applications

Abstract

Cascode HEMTs exhibit high gain and broadband performance. Promising reverse transmission makes matching networks simpler and insensitive to impedance on either side of the HEMT. On the other hand, common source (CS) HEMTs with intentional small inductance at the source provide simultaneous match for optimum noise and input impedance. This paper provides a performance comparison of 4 x 50 mu m cascode HEMTs-based low -noise amplifier and 4 x 50 mu m CS HEMTs-based low -noise amplifiers with specific emphasis on robustness, including survivability and reverse recovery time (RRT). Cascode LNA survives an input power of 33 dBm while CS LNA handles 30 dBm power, each having a 1 k Omega passive limiting resistor on the gate bias line. RRT of cascode LNA is also better. Better survivability and RRT for cascode LNA are attributed to its HEMT's stacked configuration. The designs of LNAs are described, along with their small -signal, noise, and large -signal characteristics in the X -band. Cascode LNA has a better input match, while CS LNA has a better output match. Gains are comparable, while CS LNA has better P1dB at higher band edge frequency. The noise figure for both LNAs is less than 1.9 dB, with CS LNA having a slight edge over cascode. This study benefits RF designers in choosing appropriate HEMT topology as per application for designing robust low -noise amplifiers.