Eye Source Bit Data

The Eye source can generate bit data for both QuickEye and transient analyses, using one of four methods.

• The source can link to a file that contains the data, using the BITFILE parameter. See QuickEye Bit Files for further information.
• The source can contain the sequence of 0 and 1 bits, using the BITLIST parameter. See QuickEye Bit Lists for further information.
• The source can generate a sequence of random bits, controlled by the RANDOM_BIT_COUNT and RANDOM_SEED parameters. See QuickEye Random Bit Data for further information.
• The source can generate a pseudorandom sequence of bit patterns, controlled by the PRBS_NO, PRBS_COUNT, PRBS_SEED, and PRBS_INVERT parameters. See QuickEye Pseudorandom Bit Data for further information.

If both the BITFILE and the BITLIST parameters are set, the BITFILE is used.

Any of these bit sources can be repeated using the REPEAT_COUNT parameter. The default is one time through the list (REPEAT_COUNT=0).

• The bit stream can be the worst-case pattern from Peak Distortion Analysis (PDA). When the PD_COUNT parameter is set to 1 or higher in the Quick Eye analysis setup, the Eye Source uses the worst-case bit pattern with REPEAT_COUNT set to (PD_COUNT). See Peak Distortion Analysis for further information.

QuickEye Bit Files

The BITFILE parameter on the Eye Source contains the path to the file containing the test bits. The bit file for QuickEye can be a simple text file (.txt extension) containing a list of 0s and 1s without separators.

A QuickEye bit file can also use a Coded Bit Pattern (.cbp extension). A coded bit pattern file has two entries on each line: a tag and the number of repeats. The tag entry specifies the type of bit pattern to generate:

The repeats entry tells how many instances of the given bit representation to generate. A line beginning with an exclamation point is a comment.

Here is an example of a Coded Bit Pattern file:

! example coded bit pattern file

zero 10

random 100

one 1

zero 42

lonely_1 3

QuickEye Bit Lists

The BITLIST parameter on the Eye Source specifies the sequence of 0s and 1s without separators. The bit list is preceded in the netlist by a pound sign (#) to indicate that it is binary data.

QuickEye Random Bit Data

The RANDOM_BIT_COUNT parameter on the Eye Source specifies the number of random bits to generate.

The RANDOM_SEED parameter controls the repeatability and uniqueness of the random sequence. The default RANDOM_SEED is 1000.

Repeatability. A positive RANDOM_SEED value generates the same sequence of random bits on every simulation.

Uniqueness. When two or more Eye Sources use the same positive RANDOM_SEED value, the random bit sequences is the same for all such sources, and each source generates the same sequence of bits on every run.

Negative values of RANDOM_SEED guarantee uniqueness among multiple random bit sources, with or without repeatability.

• Multiple sources with RANDOM_SEED set to -1 receive unique seeds 1000, 1001, ... 1000+(N-1), and these seeds stay the same on every simulation. (The order in which multiple sources receive seeds is indeterminate, but is the same on every simulation.)
• Multiple sources with RANDOM_SEED set to -2 receive unique seeds derived on the system clock, and these seeds is different on every simulation.

QuickEye Pseudorandom Bit Data

Setting the PRBS_NO parameter to an integer value between 2 and 31 specifies the length of the pseudorandom bit patterns. The Circuit solver randomly selects from bit pattens of the given length to generate the total number of bits requested.

The PRBS_BITLENGTH parameter specifies the total number of bits to be generated. The default is (2^PRBS_NO -1).

The PRBS_SEED parameter controls the starting value for the pseudorandom bit sequence. The default is 0 (zero).

The PRBS_INVERT parameter, when set to 1, inverts the bit values as they are generated. The default is 0 (no inversion).