SNLA236 September 2015 DS125BR111 , DS125BR401A , DS125BR820
SAS-3 is a serial interface which is often grouped in a x4 lane arrangement supported by miniSAS-HD connectors. Due to the link attenuation supported by SAS-3 devices, the SAS-3 transmitter must contribute some Tx equalization to help compensate for the total channel attenuation or loss at high frequencies. The transmitter must be able to produce individual pre- and post- cursor equalization coefficients based on the table below.
| SIGNAL CHARACTERISTIC | MINIMUM | NOMINAL | MAXIMUM | UNITS |
|---|---|---|---|---|
| Precursor Equalization Ratio RPRE | 1 | 1.66 | V/V | |
| Post Cursor Equalization Ratio RPOST | 1 | 3.33 | V/V | |
| Peak to Peak Voltage (Differential VP-P) | 850 | 1200 | mV | |
| Transmitter Device Off Voltage | 50 | mV |
NOTE
When pre- and post-cursor energy is applied, the combined equalization may be higher.
The experiments in this report demonstrate the DS125BR820’s ability to reproduce this type of transmitted waveform using active continuous time linear equalization. This capability works well with system Tx-Rx training algorithms, allowing for increased reach in SAS-3 applications.