Direct conversion linear transceiver design

Describes the implementation and performance of a prototype linear direct conversion transceiver unit, developed by the Centre for Communications Research at the University of Bristol. The transmitter and receiver system are based on the Weaver (1956) frequency translation technique. This method was chosen for the property that the image products fall in the user's own channel, thus greatly reducing the gain and phase matching requirements on the quadrature processing paths. The transmitter design includes RF amplifier linearisation by means of Cartesian closed loop feedback. Problems that have plagued this method in the past have been largely solved, and results are presented which show excellent power efficient performance through the use of linearised class C amplifier modules. Virtually any modulation format can be handled using this technique with no requirement for constant envelope.<
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