SNLS144K June 2005 – March 2024 DS40MB200
PRODUCTION DATA
The output driver has pre-emphasis (driver-side equalization) to compensate the transmission loss of the backplane that it is driving. The driver conditions the output signal such that the lower frequency and higher frequency pulses reach approximately the same amplitude at the end of the backplane and minimize the deterministic jitter caused by the amplitude disparity. The DS40MB200 provides four steps of user-selectable pre-emphasis ranging from 0, –3, –6 and –9 dB to handle different lengths of backplane. Figure 7-2 shows a driver pre-emphasis waveform. The pre-emphasis duration is 200 ps nominal, corresponding to 0.8 unit intervals (UI) at 4Gbps. The pre-emphasis levels of switch-side and line-side can be individually programmed.
PreL_[1:0] | PRE-EMPHASIS LEVEL IN mVPP (VODB) | DE-EMPHASIS LEVEL IN mVPP (VODPE) | PRE-EMPHASIS IN dB (VODPE/VODB) | TYPICAL FR4 BOARD TRACE |
---|---|---|---|---|
0 0 | 1200 | 1200 | 0 | 10 inches |
0 1 | 1200 | 850 | −3 | 20 inches |
1 0 | 1200 | 600 | −6 | 30 inches |
1 1 (default) | 1200 | 426 | −9 | 40 inches |
PreS_[1:0] | PRE-EMPHASIS LEVEL IN mVPP (VODB) | DE-EMPHASIS LEVEL IN mVPP (VODPE) | PRE-EMPHASIS IN dB (VODPE/VODB) | TYPICAL FR4 BOARD TRACE |
---|---|---|---|---|
0 0 | 1200 | 1200 | 0 | 10 inches |
0 1 | 1200 | 850 | −3 | 20 inches |
1 0 | 1200 | 600 | −6 | 30 inches |
1 1 (default) | 1200 | 426 | −9 | 40 inches |