Double balanced mixers using active and passive techniques

A variety of microwave double-balanced mixers, using dual-gate FETs or diodes as the mixing nonlinearities, have been fabricated in planar monolithic circuit technology. The mixer topologies, which use active balancing methods, eliminate the need for large suspended substrate structures, thus minimizing circuit area and facilitating integration. These approaches also eliminate IF extraction problems and allow the best performance characteristics of FETs and diodes to be combined. The mixers are insensitive to DC bias and RF termination variations and require only one balun, which can be active or passive. They exhibit excellent decade-band performance with overlapping frequency response on all ports.<>