SLVSD97A June 2017 – April 2020 ADC12DJ3200
PRODUCTION DATA.
The PRBS test modes bypass the 8b, 10b encoder. These test modes produce pseudo-random bit streams that comply with the ITU-T O.150 specification. These bit streams are used with lab test equipment that can self-synchronize to the bit pattern and, therefore, the initial phase of the pattern is not defined.
The sequences are defined by a recursive equation. For example, Equation 10 defines the PRBS7 sequence.
where
Table 39 lists equations and sequence lengths for the available PRBS test modes. The initial phase of the pattern is unique for each lane.
PRBS TEST MODE | SEQUENCE | SEQUENCE LENGTH (bits) |
---|---|---|
PRBS7 | y[n] = y[n – 6]⊕y[n – 7] | 127 |
PRBS15 | y[n] = y[n – 14]⊕y[n – 15] | 32767 |
PRBS23 | y[n] = y[n – 18]⊕y[n – 23] | 8388607 |