Referenceless single-loop CDR with a half-rate linear PD and frequency acquisition technique

A referenceless single-loop clock and data recovery (CDR) circuit with a half-rate linear phase detector (PD) and an inherent frequency acquisition technique are introduced. Cycle-slip in the half-rate linear PD and its relationship with the frequency acquisition are described in detail. The single-loop CDR consists of a conventional phase-tracking loop and a frequency-tracking unit, referred to as the cycle-slip detector. The proposed CDR is fabricated in a 28 nm CMOS process and achieves a wide capture range of 2.6 Gb/s for a PRBS31 pattern. The RMS and peak-to-peak jitter of the recovered clock are 2.40ps(rms) and 21.4ps(pp), respectively, at 8 Gb/s. The high frequency jitter tolerance is measured as 0.3UI(pp). The CDR occupies 0.105mm(2) and consumes 26 mW at 8 Gb/s from a 1.0 V supply.