A SiGe 7 Gbit/s analog BPSK/QPSK demodulator

In this paper, the authors present an analog BPSK/QPSK demodulator which employs a Gilbert-Cell multiplier and a limiting amplifier. The demodulation is done by multiplying the BPSK/QPSK input signal with an externally synchronized carrier signal. The demodulated bit stream is then recovered by the following limiting amplifier. The demodulator was tested with 50 MS/s and 3.5 GS/s QPSK signals and showed successful demodulation. The recovered bit has a voltage swing of around 580 mVpp. The measured input dynamic range is around 50 dB.