Design of 80–120 GHz broadband monolithic amplifier using self-devised InP PHEMT

This paper presents the design of a four-stage monolithic amplifier with a 90-nm InAlAs/InGaAs/InP pseudomorphic high electron-mobility transistor (PHEMT) technology. The PHEMT (0.09 × 2 × 25um²) have a dc transconductance (gm) of 1640 mS/mm with f_t >200GHz and f_max>300GHz. The four-stage monolithic amplifier is designed through schematic simulation and momentum EM co-simulation by ADS software. The high-low pass filter structures are used for matching network, edge-coupled lines are selected to block dc voltage, radial stubs are chosen as RF ground and shunt RC networks are included in the bias circuitry to maintain amplifier stability. Ground coplanar waveguide (GCPW) structures are added in input and output port. This amplifier demonstrates a small-signal gain of 24.7 dB at 105 GHz and greater than 21.5 dB gain from 84 to 114 GHz.