Modern Microwave Technology in High-Speed QPSK Communication Systems

This paper presents a technical survey and status report of the microwave subsystems presently in use in the RF portion of modern high-speed phase-shift-keying communication systems, operating at data rates up to one gigabit per second.The principal subsystems reviewed will include four-phase phase-shift modulators of both the direct-frequency type plus up-converter; the four-phase demodulators; and the microwave circuits used to derive both carrier frequency (clock) and reference phase information from a received QPSK modulated carrier. The circuits and subsystems reviewed will be discussed at the level of the technology of the associated microwave components including details of the switching diodes, high FT transistors, video amplifiers, VCO´s and special frequency multipliers involved.