A vector modulator employing four amplitude modulated orthogonal channels is presented. Operating at 28 GHz, this device consists of a four-way 6 dB power divider, four GaAs HBT MMIC variable gain amplifiers, and a 4-to-1 power combiner All of the passive functions were realised on alumina ceramic while the amplifier chips were fabricated at Nortel Technologies using a 3.5 ¿m × 6 ¿m GaInP-GaAs HBT process. By testing a vector modulator prototype, we were able to evaluate the architecture and be the first to assess its suitability as a gain/phase control element for a Ka-band MCS adaptive feedforward lineariser.

1998 28th European Microwave Conference, EuMC 1998
Department of Electronics

McPherson, D.S., Stubbs, M.G., Wight, J. S, & Lucyszyn, S. (1998). A 28 GHZ HBT vector modulator and its application to an LMCS feedforward power amplifier. In 1998 28th European Microwave Conference, EuMC 1998 (pp. 523–528). doi:10.1109/EUMA.1998.338043