A 7.5-Gb/s One-Tap-FFE Transmitter With Adaptive Far-End Crosstalk Cancellation Using Duty Cycle Detection

Abstract

A 2.5-7.5-Gb/s transmitter with one-tap feed-forward equalizer (FFE) and adaptive far-end crosstalk (FEXT) cancellation is presented. To cancel the intersymbol interference, the one-tap FFE is also employed. A crosstalk canceller (XTC) is adapted to cancel FEXT by using inverse pulses. To cancel the FEXT due to the coupled microstrip lines with various spacing, the pulse amplitude of the XTC is digitally controlled by using the proposed duty cycle detection. The one-tap FFE and the XTC are merged together to save the power. This adaptive transmitter is fabricated in a 65-nm CMOS technology. The maximum power consumption from a 1.2-V supply is 26.4 mW, and the core area occupies 0.0307 mm2 . For two 5-in FR4 printed-circuit-board traces with the spacing of 8 mil, the measured rms and peak-to-peak jitters of the recovered data are improved by 10.01 and 48.9 ps, respectively, for a 7.5-Gb/s PRBS of 27 -1 . The measured calibration time of the XTC is 1.17 μs.