Design and ASM-Based Modeling of Wideband Distributed Downconverter GaN HEMT MMICs up to D-Band

This article presents the design and modeling of two distributed resistive downconverter monolithic microwave integrated circuits (MMICs), realized in 100- and 70-nm AlGaN/GaN high-electron-mobility transistor (HEMT) technologies operating up to D-band frequencies (110–170 GHz). A dedicated transistor model that describes both the 100-nm and the scaled 70-nm HEMTs has been developed and extracted and has been used for the design of high-frequency mixers. The model is based on the physics-based advanced SPICE model for GaN HEMTs (ASM-HEMT). The standard ASM-HEMT model has been adopted by including a more precise model of the influence of velocity saturation and channel-length modulation (CLM) for both drain current and intrinsic capacitances and a crosscoupling (CC) capacitances model, to improve low-voltage mixer simulations up to at least D-band frequencies. The proposed MMICs can be operated either in a drain-pumped or gatepumped mode. At 9 dBm of local oscillator (LO) power and a fixed intermediate frequency (IF) of 200 MHz, the 70- and 100-nm gate-length drain-pumped MMICs have an average conversion gain (CG) of −8.7 dB and −9.3 dB over a wide radio frequency (RF) band of 50–150 GHz, respectively. In gatepumped operation, the CG is approximately 2 dB lower. The 100-nm HEMT MMIC has an RF input power related −1-dB compression point (P−1dB) of 3 dBm in the drain-pumped mode and the P−1dB increases to 9 dBm in gate-pumped operation. The 70-nm HEMT MMIC, in comparison, achieves a P−1dB of 2 and 10 dBm for drain and gate LO-driven operations, respectively.