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Expected Results
7
Expected Results
This evaluation board has been designed to evaluate the cable and/or FR4 signal conditioning
performance of the DS125BR111. Adding additional cables or adaptor boards into the signal path will
have some impact on the optimal settings, but keeping the adaptor boards small and using short high-
quality SMA cables will minimize this effect.
7.1
Performance
When used in a PCIe or SAS system, it is generally expected that the DS125BR111 will be receiving a
signal with embedded TX FIR information. The DS125BR111 works to extend the reach possible by
adding active linear equalization to the channel, boosting attenuated signals so that they can be more
easily recovered at the SAS-3 Rx. The outputs are specially designed to be transparent to TX FIR
signaling passing this information critical for optimal link training to the SAS-3 Rx. The typical device
settings used in most SAS-3 environments are EQ = Level 4, VOD_DB = 0 and VOD_SEL = 1 in Pin
mode or EQ = 03'h, VOD = 111'b, and VOD_DB = 000'b in SMBus mode.
SETUP1: PRBS7 Generator (no TX FIR)
→
10" FR4
→
DS125BR111EVM
→
Scope
DS125BR111 Settings
1. VOD_SEL = 1
2. VOD_DB = 0
3. EQ0 = 1
Additional documentation and device performance is available in the device datasheet.
Figure 3. 12 Gbps Eye Diagram at SCOPE in SETUP1
7
SNLU168A – August 2014 – Revised August 2014
DS125BR111EVM User's Guide SMA Evaluation Kit
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