A 1.0625-to-14.025Gb/s multimedia transceiver with full-rate source-series-terminated transmit driver and floating-tap decision-feedback equalizer in 40nm CMOS

A robust transceiver designed for NRZ signaling beyond 10Gb/s over long-range physical media (including electrical backplanes, copper cables and optical modules) must contend with significant challenges from insertion loss, crosstalk, and reflection. For inter-symbol interference (ISI) cancellation, half-rate decision-feedback equalizer (DFE) with unrolled first tap [1–3] is widely used to avoid noise amplification and to relax timing for data sampling/feedback. However, tap-unrolling increases slicer count and entails half-rate multiplexers eating into timing margin. To remove reflection-induced ISI due to impedance discontinuities in the media, the DFE must cover tap positions higher than 30UI which is beyond tap range of the DFEs reported in previous work [1–4]. Fig. 1 shows an example of bumpy channel with reflection energy up to 40UI.