A Modular Phase-Locked BPSK, QPSK Demodulator With a Single-Phase VCO

A phase-locked BPSK/QPSK demodulator with a single-phase voltage-controlled oscillator (VCO) is proposed. Relying on a linear voltage/phase-difference characteristic of the phase detector, a phase-control process of this single-loop demodulator architecture is simple and truly modular. Such process is done by selective voltage shifting and re-scaling to ensure no significant change at the VCO’s input regardless of the incoming modulated signals’ phase. The prototype has been fabricated in a 0.18-μm CMOS process operating under a 1.8-V supply with a 60-MHz carrier. The BPSK and QPSK demodulators achieve maximum data rates of 25 Mbps while consuming 0.68mW and 0.79mW, respectively with the corresponding energy per bit figures of 27.2 and 31.7 pJ/bit.