Multi-Gb/s Analog Synchronous QPSK Demodulator With Phase-Noise Suppression

In this paper, an IF quadrature phase-shift keying demodulator is presented, which performs phase and frequency synchronization in the analog domain. The presented demodulator can be utilized for short-range ultra-wideband wireless communication scenarios, and can greatly simplify the wireless system by relaxing the demands on digital signal processors. The demodulator is implemented as a low-cost system-in-package RF module, including a very narrow bandwidth microstrip bandpass filter on a Teflon substrate. The analog carrier recovery and synchronization is experimentally characterized using custom designed modules for multi-Gb/s test signal generation. Furthermore, it is shown that the presented carrier recovery concept exhibits very efficient phase-noise suppression. The results demonstrate successful coherent demodulation up to a data rate of 6.2 Gb/s, a very high dynamic range, and robustness against undesired phase and frequency fluctuations.