Abstract

Four phase direct demodulation systems and high bit rate telemetry require four phase modulator. This work describes a four phase modulator development and a demodulator design at X-band frequency in MMIC technology. The modulator and demodulator MMIC design uses lumped elements networks and a 0.5 microns gate length process. Demodulator simulation results are presented. The modulator has been realized, it exhibits low consumption due to the use of cold FETs. Small phase switching times, less than 300 picoseconds, have been measured which confirm high bit rate modulator capability. Carrier rejection of about 28 dB and high clock rejection level are obtained in a QPSK modulation spectrum.