In-Situ De-embedding (ISD) is an innovative de-embedding tool to give causal DUT results. Many de-embedding tools “subtract” test coupons directly for de-embedding, so DUT results become non-causal when test coupons and actual fixture have different impedance. ISD uses test coupons only as reference and is insensitive to impedance variation, resulting in better accuracy and $$$ savings.

What is Causality ?

  1. the relationship between cause and effect.
  2. the principle that everything has a cause.

In other words:
     Can not get something from nothing.  
The non-causal response after TRL, which is attributed to the impedance variation between TRL calibration board and actual DUT test fixture, is clearly seen in the following figure. ISD is free of causality error. Note the big difference in return loss, too.


How did ISD do it?

Through optimization, ISD de-embeds fixture’s impedance exactly, independent of 2x thru’s impedance.

ISD advantages:
1. Gives more accurate and causal results
2. Uses standard substrates, etching tolerances and connectors for the test fixture and coupons
3. Extracts crosstalk from a single trace test coupon
4. Extracts small DUT from a large board
5. De-embeds asymmetric structures
6. Runs in batch to stack up multiple jobs