Title :
A 28 GHz HBT Vector Modulator and its Application to an LMCS Feedforward Power Amplifier
Author :
McPherson, D.S. ; Stubbs, M.G. ; Wight, J.S. ; Lucyszyn, S.
Author_Institution :
Department of Electronic Engineering, University of Surrey, Guildford, Surrey GU2 5XH, United Kingdom. d.mcpherson@ee.surrey.ac.uk
Abstract :
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.
Keywords :
Amplitude modulation; Ceramics; Gain; Gallium arsenide; Heterojunction bipolar transistors; MMICs; Power amplifiers; Power combiners; Power dividers; Testing;
Conference_Titel :
Microwave Conference, 1998. 28th European
Conference_Location :
Amsterdam, Netherlands
DOI :
10.1109/EUMA.1998.338043
