A 180-GHz monolithic subharmonic diode mixer is developed using 0.08-mu m p
seudomorphic InAlAs/InGaAs HEMT MMIC process on a 2-mil-thick InP substrate
, This mixer demonstrates a conversion loss of better than 16.5 dB from 175
to 182 GHz with an LO drive of 13 dBm at 96 GHz, This is the first demonst
ration of a monolithic subharmonic HEMT diode mixer in this frequency range
. The design and measurement of this monolithic microwave integrated circui
t (MMIC) mixer and the waveguide-to-microstrip line transitions of the test
-fixture are presented.