A 32-Gb/s PAM-4 Quarter-Rate Clock and Data Recovery Circuit With an Input Slew-Rate Tolerant Selective Transition Detector

We present a 32-Gb/s PAM-4 quarter-rate clock and data recovery (CDR) circuit having a newly proposed selective transition detector (STD). The STD allows phase detection of PAM-4 data in a simple manner by eliminating middle transition and majority voting with simple logic gates. In addition, using the edge-rotating technique with quarter-rate CDR operation, our CDR achieves power consumption and chip area reduction. A prototype 32-Gb/s quarter-rate PAM-4 CDR circuit is realized with 28-nm CMOS technology. The CDR circuit consumes 32 mW with 1.2-V supply and the recovered clock signal has 0.0136-UI rms jitter.