A surface mount vector modulator for PCS

Abstract

Adjusting the amplitude and phase of a signal is the purpose of the vector modulator which has applications in feedforward power amplifiers, beamforming networks and other networks requiring phase and amplitude adjustments. The vector modulator designed here is a variable resistive device consisting of three, 3dB hybrid couplers, a Wilkinson power divider, four PIN diodes and DC biasing circuitry. The device designed is controlled by two independent current sources that allow between 6dB and 26dB attenuation and full 360° phase shift. Analysis of the entire network and the importance of the parasitics in the PIN diodes are described along with measured results of the implementation of linearizing the PIN diodes.