110 GHz vector modulator for adaptive software-controlled transmitters

A 110 GHz MMIC vector modulator for use in low-cost, high-performance, rada r and communication transmitters is presented, The circuit consists of two push-pull (bi-phase) attenuators arranged in phase quadrature and has dimen sions of 1.7 x 1.4 mm(2). The fabricated MMIC has been characterized by mea ns of static S-parameter measurements and shows a minimum insertion loss of 12 dB at 110 GHz, Using these measurements, the required baseband input le vels for a 64-QAM static constellation were determined. These levels were t hen applied at 10 MSample/s, by an arbitrary waveform generator, to demonst rate a 60 Mb/s data rate transmitter operating at 110 GHz. To date, this re presents the highest reported RF frequency for direct multilevel carrier mo dulation using monolithic technology.