Dual-Gate GaN MMICs for MM-Wave Operation

This letter describes the millimeter-wave operation of III-N dual-gate MMICs based on a complete mm-wave MMIC technology suitable for operation up to 110 GHz. The GaN HEMTs have a gate length of 100 nm, yield high maximum transconductance, and very low parasitic capacitances. The cutoff frequency fT is above 80 GHz at an operation bias of 15 V in a fully passivated device. Dual-gate devices were developed for high gain at high gate widths and for substantial improvements in gain per stage on MMIC level. Complete III-N MMICs in grounded coplanar passive technology were designed. A single-stage dual-gate MMIC at 60 GHz yields 150 mW (840 mW/mm) of output power. A second MMIC shows a linear gain of greater than 10 dB at 94 GHz. It further yields an output power of 22.8 dBm (190 mW or 520 mW/mm) in CW-operation to a 50 Ω load with a maximum PAE of 7% at 94 GHz. The letter demonstrates the advantage of GaN dual-gate devices in power gain over common-source devices while maintaining essential improvements in power density.