94 GHz single balanced cascode mixer using CPW tandem couplers

We report on a high isolation 94 GHz MMIC single balanced cascode mixer using 0.1 mum metamorphic high electron mobility transistor (MHEMT) and CPW tandem couplers. Tandem couplers are introduced to overcome the limits of CPW based conventional directional couplers. Conversion loss of the single balanced cascode mixer was 9.8 dB at an LO power of 10.9 dBm. PldB (1 dB compression point) was -14.8 dBm at an input power of -4 dBm. The LO to RF isolation at 94 GHz and 100 GHz were -29.5 dB and -39.5 dB, respectively.