A compact Ka band sub-harmonically resistive mixer MMIC using miniature hybrid elements

This work reports a compact monolithic sub-harmonically pumped resistive mixer (SPRM) with miniature hybrid elements which include a capacitive compensation balun and a reduced size power divider. This MMIC mixer was fabricated by using Win-semiconductors 0.15μm GaAs pHEMT technology. The proposed power divider utilizes a combination of shorted coupled lines instead of lumped inductors and capacitors. The traditional the length of Marchand balun are significantly reduced by shunted capacitors. The balun and divider are then applied in the design of a 28-GHz monolithic SPRM. As a result the dice area of SPRM only occupies 1.5mm². The measured conversion loss of the mixer is less than 13 dB at an RF bandwidth of 27.5-28.5 GHz at 1 GHz fixed IF frequency, over 35 dB of LO-RF isolation, and a 9 dBm of 1-dB compression point.