SNLA236 September   2015 DS125BR111 , DS125BR401A , DS125BR820

 

  1.   Linear Repeaters Used in SAS/SATA Applications
    1.     Trademarks
    2. 1 Introduction
    3. 2 SAS-3 Transmit Waveforms
      1. 2.1 Default Transmit Equalization Coefficients
      2. 2.2 Using Linear Equalization to Recover Tx FIR Information
      3. 2.3 Linear Equalization Effects on Jitter Due to Attenuation
    4. 3 Equalizer Placement within a SAS-3 Channel
    5. 4 System Results Using Linear Equalization
      1. 4.1 Linear Equalization Effects on Jitter Due to Attenuation
      2. 4.2 Channel Extension
    6. 5 Passing Out Of Band (OOB) Signals
    7. 6 Conclusions
    8. 7 Appendix A: Layout Considerations
  2.   Revision History

2.1 Default Transmit Equalization Coefficients

SAS-3 defines a pair of Reference waveforms, Reference 1 (left side) and Reference 2 (right side). In many cases Reference 1 is used as a starting point for link training.

typical_host_transmitter_reference_waveforms_snla236.gifFigure 2. Typical Host Transmitter Reference Waveforms

The voltage specifications for Reference 1 and Reference 2 waveforms are listed in Table 2.

Table 2. SAS-3 Reference Waveform Characteristics

WAVEFORM Va Vb Vc Vd Va/Vb Vc/Vb POST CURSOR PRE CURSOR
Reference 1 1.03 0.725 0.915 1.20 1.42 1.262 -3 dB 2 dB
Reference 2 0.84 0.23 0.61 1.20 3.65 2.652 -11.2 dB 8.5 dB
No Tx Eq 1.20 1.20 1.20 1.20 1 1 0 dB 0 dB