Quadriphase integrated high-speed microwave modulator

A quadriphase modulator, designed in a planar metal geometry for operation in the microwave frequency range, uses Schottky barrier diodes as the switching elements, and is capable of operating at bit data rates up to 15% of the carrier frequency. The microwave circuit employs a microstrip power splitter that couples the carrier signal to two biphase modulators while providing DC isolation. Each biphase modulator includes coplanar-to-slot transmission line transition, with a pair of diodes controlling the phase shift across the transition. The diodes are connected in reverse polarity and the bias for switching the diodes is controlled by the modulating signal. The slot lines from the two biphase modulators are coupled through a microstrip transition and through a Lange 90 degree hybrid to the output load.