Altera JNEye User Manual

Page 172

Figure 3-21: CTLE Output Hybrid Eye Diagram and BER Analysis with CDR Recovered Clock

When you enable CDR in a receiver, the reference clock’s phase noise is shaped and filtered with the

CDR’s response. The following figure shows the characteristics of phase noise at the output of the

reference clock (blue), after the transmitter PLL (red), after the transmitter PLL plus the transmitter’s

intrinsic jitter (red), after the RX CDR (cyan), and after the RX CDR with transmitter and receiver’s

intrinsic jitter (black). The associated random jitter from the phase noise power spectrum at each of the

above stages was calculated and displayed in the text below the plot.

UG-1146

2015.05.04

Analysis

3-21

Tutorial: PCI Express 8GT

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