A fully monolithic 4-18 GHz digital vector modulator

A fully monolithic vector modulator covering the entire 4-18 GHz band and featuring independent direct digital control of amplitude and phase is presented. The modulator output amplitude can be varied over a 25-dB range with 32 steps of resolution and the phase can be independently varied over 360 degrees with 32 steps. The vector modulator chip set consists of a miniaturized 5-b MMIC (monolithic microwave integrated circuit) phase shifter and a 5-b MMIC segmented dual-gate distributed variable-gain amplifier-attenuator. The chips are assembled on a carrier measuring less than 0.4 in *0.5 in and require no supporting RF-hybrid hybrid or DAC (digital-to-analog converter) circuitry. The vector modulator demonstrates state-of-the-art performance with ultrawide (instantaneous) bandwidth, high uncorrected accuracy and resolution, and direct digital control with a potential transition time of a few nanoseconds. In addition, the individual MMIC chip performance is the best reported to date for ultrawide bandwidth phase and amplitude control functions.<>