A Q-band uniplanar MMIC diode mixer with lumped-element coplanar waveguide-to-slotline transition

A uniplanar GaAs MMIC diode mixer is fabricated for Q-band applications using the lumped-element coplanar waveguide-to-slotline transition to implement the required 180/spl deg/ hybrid. By adopting the lumped-element transition, the mixer chip size can be largely reduced with an excellent RF-to-IF isolation. This mixer is designed to operate with RF frequency from 34.5 to 43 GHz, IF frequency from 0.5 to 9 GHz, and LO frequency at 34 GHz. The lower sideband conversion loss is about 7 dB, and the isolations are all better than 20 dB. To our best knowledge, it is the first MMIC with such transition topology in Q-band.