A 12.5-Gb/s Parallel Phase Detection Clock and Data Recovery Circuit in 0.13- CMOS

A clock and data recovery (CDR) architecture featuring a parallel phase detector is proposed for speeding up linear-type CDRs. A cause of speed limit in conventional CDRs is very short UP pulses in its phase detector circuit. The parallel phase detector expands UP pulsewidth by adding fixed-width using a half-rate clock. The parallel phase detector is used in the CDR with a couple of unbalanced charge-pump. The bandwidth of decision latches of the PD is extended by 1.7 times by using both shunt-peaking and capacitance coupling. The monolithic CDR implemented in 0.13-mum CMOS shows 1.7 times wider phase linear response region of 0.56UI than that of a conventional CDR. It operates at 12.5-Gb/s with PRBS 2³¹-1 input data. Measurements show large jitter tolerance of over 0.5 UIpp for 4-8 MHz jitter frequency as well as jitter transfer characteristics independent on input-jitter amplitudes of 0.1, 0.3, and 0.5 UIpp