A 0.8-to-6.5 Gb/s Continuous-Rate Reference-Less Digital CDR With Half-Rate Common-Mode Clock-Embedded Signaling

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This paper presents a continuous-rate reference-less clock and data recovery (CDR) circuit that utilizes common-mode clock-embedded signaling (CM-CES) and injection locking techniques to reduce design complexity for the half-rate data recovery. In the proposed receiver, the use of wideband injection-locked oscillator (ILO) greatly suppresses its phase noise while the narrowband digital phase tracking loop (DPTL) tunes retiming phase. For wide-range and continuous-rate operation, four circuit techniques have been adopted: a VCO with active inductance load for low VCO gain at high frequency, a wide-range digitally-controlled delay line (DCDL) with adaptive band selection, a linearized delay control unit with CM-to-delay conversion technique, and a coarse frequency detection scheme to drive the free-running oscillator frequency toward injection locking. The prototype CDR, fabricated in low power CMOS 65 nm technology, successfully detects 0.8–6.5 Gb/s data rates over 5 $^{\prime\prime}$ FR4 trace with $2^{31}-1$ PRBS pattern satisfying ${\text{BER}} . The power efficiency was 2.4 mW/Gb/s at 6.5 Gb/s.