A 3.12 pJ/bit, 19–27 Gbps Receiver With 2-Tap DFE Embedded Clock and Data Recovery

A 19-27 Gbps receiver comprised of a continuous-time linear equalizer (CTLE) followed by a 2-tap decision feedback equalizer embedded clock and data recovery circuit is implemented. The hybrid CDR is operated at half rate, which is incorporated into a broadband PLL to facilitate ISI and jitter suppression over wide-band operation. To accommodate different channel response, an automatic threshold tracking (ATT) circuit combining with sign-sign least mean square (LMS) adaptive engine is realized. A quadrature relaxation-type oscillator is proposed to provide the sampling phases without bulky inductors. It also provides the advantages of small form factor and wide range operation (19-27 Gbps) to compensate 20 dB channel loss at 12.5 GHz. Fabricated in a 40 nm CMOS technology, the whole receiver manifests an energy efficiency of 3.12 pJ/bit at 27 Gbps operation. The core area is 0.09 mm² only.