250 Mbps–5 Gbps Wide-Range CDR With Digital Vernier Phase Shifting and Dual-Mode Control in 0.13 $\mu$ m CMOS

A multi-port serial link with wide-range CDR using digital vernier phase shifting and dual-mode control is presented. The proposed vernier phase shifter generates finely-spaced phase steps and provides unlimited phase rotating with a 13.34-ps phase step at 5 Gbps. By inherently digital nature, the vernier phase shifter enables semi-digital dual-loop CDR with precise tracking performance, and with the dual-mode control, the proposed CDR extends the operating range from 250 Mbps to 5 Gbps and achieves a BER of less than 10^-12 at 5 Gbps with 2⁹-1 PRBS. Fabricated in a 0.13-μm CMOS process, the main PLL and the single receiver dissipate 9.0 mW and 19.2 mW respectively at 5 Gbps from a 1.2 V supply.