A millimeter-wave ultra-compact broadband diode mixer using modified Marchand balun

In this paper, a broadband mixer has been developed using 0.15-/spl mu/m pHEMT technology. This singly balanced mixer was realized by using Schottky diodes. A modified Marchand balun was employed at the LO port and matched to the diodes directly to achieve wideband performance and compact size. This diode mixer achieves conversion loss of better than 10 dB from 46 to 78 GHz with LO power of 12.5 dBm, and the chip size is only 0.57 mm /spl times/ 0.52 mm. Compared with previously reported MMIC mixers in millimeter-wave frequencies, this circuit has the smallest chip size with competitive performance and wide bandwidth.