Altera Stratix GX Transceiver - Manual (Page 207)

Altera Corporation 8–3
January 2005 Stratix GX Transceiver User Guide
Stratix GX Built-In Self Test (BIST)
PRBS mode is enabled when the PRBS option is enabled in the Quartus II
software. The 8b-10b encoder/decoder is bypassed automatically in this
mode.
You can use PRBS generation to test the functionality of both the
transmitter and receiver, to test if the BIST verifier is enabled, or to
measure the quality of the transmission medium. The advantage of using
a PRBS data stream is that the randomness yields an environment that
stresses the transmission medium. In the data stream both random jitter
and deterministic jitter are observed either by a time interval analyzer
(TIA), a bit error rate tester, or an oscilloscope.
Incremental Mode Generator
In the incremental mode, the data generator sweeps through all the valid
8b/10b data and control characters. You can also enable the incremental
BIST verifier to perform a quick verification of the 8B/10B
encoder/decoder paths. Refer to
“Pattern Verifier” on page 8–5 for more
information.
Incremental mode is enabled when option 1 is selected under the what
self test mode do you want to use?
option in the Quartus II software. In
this mode, the BIST generator sends out the data pattern in the following
sequence: K28.5 (comma), K27.7 (Start of Frame, SOF), Data (00-FF
incremental), K28.0, K28.1, K28.2, K28.3, K28.4, K28.6, K28.7, K23.7, K30.7,
K29.7 (End of Frame, EOF) and repeat. The 8b/10b encoder must be
enabled for proper operation.
Because the 8/b10b encoder is enabled, the data stream is DC balanced.
8b/10b encoding guarantees a run length less than 5 UI, which yields a
less stressful pattern than the PRBS data. However, because the PRBS
generator bypasses the 8b/10b paths, you can use the incremental BIST to
test this path.
High-Frequency Mode Generator
In high-frequency mode, the BIST generator transmits a D21.5
±(8'b10110101) character into the 8b/10b encoder to generate a
10'b1010101010
high-frequency character. This toggling data is the
highest frequency that the data stream can transmit.
This pattern is DC balanced; the number of ones is equal to number of
zeros. This fact is important when trying to perform a first-order random
jitter measurement. You can measure this jitter using an oscilloscope with
a histogram defined at the zero crossing point. This method is crude, but
still yields a first-order estimated value, because the majority of the