![Lauterbach AutoFocus User Manual Download Page 51](http://html.mh-extra.com/html/lauterbach/autofocus/autofocus_user-manual_680294051.webp)
AutoFocus User’s Guide
51
©1989-2018 Lauterbach GmbH
Measure the setup and hold times for all data channels, which will also give you the maximum channel-to-
channel skew. The AutoFocus preprocessor can handle data skew, but a minimum setup and hold time slot
has to be fulfilled for all channels. The following picture shows how to measure setup/hold times.
The threshold level should be set to the middle of the trace signal. The following table shows setup and hold
time requirements for different AutoFocus preprocessors.
The AutoFocus II technology is very powerful, if it comes to configuring itself for different target trace
ports. Usually you do not need to worry about setup and hold times for data rates as high as 200 Mbit/s,
although it is always a good idea to keep the channel-to-channel skew low and the clock duty cycle close to
50/50. Depending on your trace port data rate the maximum channel-to-channel skew has to stay below:
ch2ch_skew <= t_period - (Ts + Th)
For instance, a trace port with a data rate of 300 Mbaud/s should have no more than
(1/300 MHz - 2 ns) = 1.33 ns channel-to-channel skew. In addition the maximum operation frequency has
to be considered, see tables in
“AutoFocus Preprocessor Hardware Versions”
, page 62.
AUTOFOCUS
Ts + Th >= 1.2 ns
AUTOFOCUS II
Ts + Th >= 0.3 ns
The given data are absolute minimum values. The signal must be stable for this
time including all possible jitter and the eye must be open (amplitude) at least 0.5V.