Design of 60 GHz Millimeter-Wave Frequency Doubler using Distributed Structure

A millimeter-wave distributed frequency doubler has been designed with distributed block and frequency tunable output reflectors. The simulated conversion loss of 9.5 dB to 7.7 dB from 54.6 GHz to 62.4 GHz output frequencies is achieved with fundamental and third harmonic signal rejections of more than 10 dBc. The fabricated chip has the size of 1.2 mm x 1.0 mill. Some measured results of frequency and bias dependent characteristics arc presented for the fabricated PHEMT MMIC frequency doubler. The designed doubler has two transistors, and if one of the transistors fails the doubler unit still operates with reduced gain. The failure effect of the PHEMT has been simulated, and compared to the measured data of which one PHEMT is not operating properly.