A 0.002-mm $^{2}$ 6.4-mW 10-Gb/s Full-Rate Direct DFE Receiver With 59.6% Horizontal Eye Opening Under 23.3-dB Channel Loss at Nyquist Frequency

This paper reports a full-rate direct decision-feedback-equalization (DFE) receiver with circuit techniques to widen the data eye opening with competitive power and area efficiencies. Specifically, a current-reuse active-inductor (AI) linear equalizer is merged into a clocked-one-tap DFE core for joint-elimination of pre-cursor and long-tail post-cursors. Unlike the passive-inductor designs that are bulky and untunable, the AI linear equalizer offers orthogonally tunable low- and high-frequency de-emphasis. The clocked-one-tap DFE resolves the first post-cursor via return-to-zero feedback data patterns for sharper data transition (i.e., horizontal eye opening), and is followed by a D-flip-flop slicer to maximize the data height (i.e., vertical eye opening). A 10-Gb/s DFE receiver was fabricated in 65-nm CMOS. Measured over an 84-cm printed circuit board differential trace with 23.3-dB channel loss at Nyquist frequency (5 GHz), the achieved figure-of-merit is 0.027 pJ/bit/dB (power consumption/date rate/channel loss). At 10^-12 bit error rate under 2⁷-1 pseudorandom binary sequence, the horizontal and vertical eye opening are 59.6% and 189.3 mV, respectively. The die size is 0.002 mm².