Abstract

Subharmonic mixers appeared in the early thirties as a solution to minimize LO radiation from superheterodyne receivers, and to obtain higher effective LO frequencies.  However, their overall performance compared to fundamental mixers was far from desirable, so they did not receive the attention they deserved.  Despite the drawbacks, the concept had several revivals over the years mainly caused by technology developments from tubes to Schottky diodes on silicon, high-frequency bipolar devices, GaAs FETs, and most recently Silicon CMOS FETs. In recent years, the demand for wireless communications began favoring direct receiver approaches as a means to cut cost but the old LO radiation problem surfaced again. Fortunately, circuit technology also evolved over the years so that modern subharmonic mixers now have acceptable performance levels, allowing their application into wireless systems. This presentation gives an overview of the evolution of subharmonic mixers and reports on the important milestones of this technology.

Biography

Edmar Camargo received his Master and Ph.D. degrees from University of São Paulo, Brazil in 1976 and 1985 respectively. He was a Teacher Assistant and Research Engineer in the same University for 17 years. During this time he was active in several areas of microwave art in Brazil and spent nearly two years in France. He emigrated to the US in 1993 where he worked for Hewlett-Packard on millimeter-wave transceiver design, for Fujitsu Compound Semiconductor on frequency converters, high power millimeter-wave amplifiers and mobile PAs. He also worked at WJ Communications on HBT PA designs and at RFMD on Front End Modules. Presently is working as a consultant on power amplifiers.