A 7.8-Gb/s 2.9-pJ/b Single-Ended Receiver With 20-Tap DFE for Highly Reflective Channels

Abstract

For the first time, we prove that 7.8-Gb/s single-ended signaling through a highly reflective channel is feasible at low energy cost by an energy-efficient many-tap decision feedback equalization (DFE) receiver (RX). The reported data rate of 7.8 Gb/s is the fastest data rate that has been achieved through a single-ended highly reflective channel that has more than five taps of postcursor reflective intersymbol interference. Compared with the prior arts, the target multidrop has the most in-band notches: ten notches. To compensate for large reflection by many notches, the RX exploits the DFE with the largest tap count of 20 that has been never used in single-ended signaling before. Low-power circuit techniques such as a current-integrating summer and double-tail sense amplifiers were adequately adopted and engineered to reduce large power dissipation by many taps. The RX was fabricated in a 65-nm CMOS technology and occupies only 0.014 mm2. The energy efficiency was measured to be only 2.9 pJ/b at 7.8 Gb/s with 0.9-V supply, proving that fast single-ended signaling through a highly reflective channel is feasible at low energy cost by many-tap DFE if low-power circuit techniques are adequately applied. The horizontal and vertical eye sizes were measured to be 0.12 UI and 34 mV, respectively, at a bit error rate of <10−12.