MMIC CIRCUITS ENABLE DIRECT-CARRIER MODULATION - VECTOR MODULATOR DESIGN, PART 1

DIRECT-CARRIER modulation is expected to find widespread use in commun ications transceivers, since it promises lower cost and smaller system size due to reduced hardware requirements, By using a microwave-monol ithic-integrated-circuit (MMIC) phase shifter and variable attenuator to provide phase and amplitude control, a single-chip transmitter desi gn aimed at indoor radio applications achieves direct-carrier modulati on in the 17/18-GHz frequency range, The first part of a two-part arti cle describes the various circuit topologies available for implementin g the phase shifter and variable attenuator, examining the performance and fabrication characteristics of the candidate designs.