Abstract

In this paper, a novel monolithic balanced FET mixer is described, which has a measured conversion gain of ldB over 5 to 12 GHz. A new circuit technique has been developed which gives both high performance and low complexity. As a result, the mixer is expected to find applications in state-of-the-art monolithic subsystems for communications and radar. The technique employed is to use a passive lumped-element Wilkinson combiner feeding a common-source/common-gate FET pair. The FETs operate as both active balun and mixer elements, giving a very compact balanced mixer. After an exhaustive investigation of MMIC mixers, this new technique is thought to be the optimum blend of active and passive circuitry. As a result, the mixer has the same simplicity and ease-of-use associated with existing double-balanced diode mixers, but in addition has conversion gain and can be directly integrated into MMIC subsystems.