Altera JNEye User Manual
Page 155
Figure 3-3: Channel Characteristics (Using JNEye Channel Viewer with Data Cursor Enabled)
The JNEye Channel Viewer shows that the backplane channel has approximately 17.15 dB loss at 4 GHz.
The PCI-SIG RX package has 3.5 dB insertion loss at 4 GHz. The overall link has about 21 dB of loss (as
shown in the Combined Channel black curve, not including Stratix V GX transmitter package) at 4 GHz,
which requires heavy TX and RX equalizations to achieve the required BER target.
For comparative purposes, the following table and figure show a typical external 100 MHz transmitter
reference clock with measured phase noise characteristics and spurs at three different frequencies.
Table 3-1: Phase Noise Characteristics
Phase Noise
Spurs
Frequency
Phase Noise (dBc)
Frequency
Amplitude (dBc)
10 Hz
–68
100 KHz
–80
100 Hz
–82
1 MHz
–90
3-4
Methodology
UG-1146
2015.05.04
Altera Corporation
Tutorial: PCI Express 8GT