A 10-14 GHz linear MMIC vector modulator with less than 0.1 dB and 0.8 degrees amplitude and phase error

Abstract

The design, fabrication, and performance of a GaAs monolithic linear vector modulator in the 10-14 GHz band is described. The circuit exhibits sideband and carrier rejections of more than 45 dB with third-order intermodulation signals at -40 dBc. Such performance has never been obtained in hybrid or monolithic technology. The design is based on symmetrical circuits. The vector modulator comprises two monolithic binary-phase-shift keying (PSK) modulators, a monolithic quadrature power divider, and a Wilkinson power combiner. The modulator is ideal for direct 16-quadrature amplitude modulation (QAM) in X-Ku-band digital radio links and satellite communications. Due to its linearity, amplitude, and phase precision, it has numerous applications, such as for an analog phase shifter for phased-array antennas or for a single-sideband up converter.<>