Mixers

Single-chip transmitters and receivers are the most desirable MMIC products, preferably packaged with only four pins (input-output-ground-DC) and costing less than #l. The major applications are mobile communications, wireless LANs, satellite TVROs, and wireless local loop outdoor units. Frequency translation is the fundamental function of these MMIC transmitters and receivers: i.e. the function of converting baseband signals to and from the microwave carrier using a mixer. Other functions, such as amplification and filtering have to be introduced to mask the mixer's shortcomings. In this context the author discusses the following: active mixers; lumped-element designs; active splitters and combiners; milimetre-wave mixers; and distributed mixers.