Signal integrity validation of de-embedding techniques using accurate transfer functions

Abstract

De-embedding techniques are frequently applied to signal integrity measurements to remove the unwanted effects of test fixture and thereby isolate the device under test (DUT) performance from the rest of the system. Conventionally, the transfer function (TF) of the channel to be de-embedded could be obtained independently without capturing its interaction to the DUT. However, as data rates increase and channels become more complex, the errors due to discontinuities at the channel to DUT boundary need to be given due consideration. This paper provides simulation and measurement examples to illustrate this effect and proposes a modified approach of generating the channel TF to compensate for those errors. The proposed approach effectively improves the accuracy of the de-embedded result. It can also be used as a validation scheme to correlate the de-embedding accuracy for a given application.