E/D pHEMT Multi Frequency Generator GaAs MMIC for Aerospace Applications

This paper presents the design and performance of a multi frequency generator MMIC to be used in transmit/receive modules for S band transponders. The technology used is a European commercial Enhancement/Depletion (E/D)pHEMT process,compatible with low noise reception.Quasi-monolithic Voltage Controlled Oscillator (VCO),divide-by-four digital frequency divider,active frequency multiplier-by-three and relative power dividers and buffers have been integrated into a single chip to generate all the system frequencies in a flexible architecture. Measured phase noise of the VCO depends on the external resonator and varactor used.Values of –105dBc/Hz@100KHz have been measured with external high Q resonator which is comparable to best performance reported of GaAs based VCOs.The frequency divider by four has an operating window from 30 MHz to >4GHz and an output power of more than 4 dBm.Multiplier by three provides more than 5 dBm in each of the two outputs with adjustable level of harmonics.