W2308EP Datasheet, PDF (19/26 Pages) Keysight Technologies – Quick Start for Signal Integrity

Channel Simulator: Bit-by-Bit Mode
By now you might be asking, “What’s the difference
between traditional transient (SPICE-like) simulation and
the two modes of Channel Simulator?”
Bit-by-bit mode works in two phases. First, we probe your
schematic with a single step input. We use the transient
simulator but we also automatically use convolution to
deal with any components defined in the frequency domain
and EM simulators to deal with distributed layout compo-
nents. The computationally expensive transient simulation
needs to run only for a short length of time, equal to the
pulse response of the channel.
In phase two we use the step response from the above
phase one as a linear time invariant model. We can then
use computationally inexpensive superposition to calculate
the output for millions of bits without having to call the
transient, convolution, or EM simulators again.
Phase 1:
SPICE-like transient response of single step
– runs on existing schematic
In statistical mode, again we have two phases. The first
phase is the same as for bit-by-bit mode, but the second
step is much quicker. There’s no need for brute force
superposition of each bit: just some mathematical calcula-
tions based on:
–– ISI and crosstalk implied in the through and crosstalk
pulse responses
–– Jitter spec
–– Equalizer spec
–– Line coding
Phase 1:
SPICE-like transient response of single step
– runs on existing schematic
Phase 2:
Million-bit-per-minute throughput using
superposition
Phase 2:
Million-bit-per-minute throughput using
superposition
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