The Impact of CTLE Poles on Receiver Eye Diagrams

As the data transmission demand increases, the time margin for receiver sampling becomes smaller rapidly. Particularly at the 224Gbps node, the overall time margin may be less than 1ps. Since the IUI-spaced feed-forward equalizer and decision-feedback equalizer cannot equalize the frequency responses above the Nyquist frequency in theory, the continuous-time linear equalizer becomes the only module in wireline receivers that increases the eye width. This paper constructs a bit-by-bit time-domain model of a receiver and discusses the relation between poles of continuous-time linear equalizer and the margin of the eye diagram. The simulation results show that when the channel noise is low, raising the poles can effectively increases the eye height and eye width. However, when the crosstalk noise is comparable to the amplitude margin, the eye opening will be overwhelmed if using poles higher than the Nyquist frequency.