Mike Li, Chief Technical Officer, Wavecrest

It is well known that the I/O signals measured by a test and measurement equipment are due to not only the device under test (DUT), but also the test interfaces. For example, if the data-dependent jitter (DDJ) and data-dependent noise (DDN) due to the test path-including test fixture, cable, and socket-are not negligible, then the performance of the DUT will be grossly underestimated for the output testing and overestimated for the input tolerance testing. At multiple Gbps data rates, the signal and jitter degradation due to test interface have become so severe that they must be reduced or guardbanded. In this paper, we propose a generic model for both the test interfaces and the DUT. By using a cascading model, we will illustrate the measured signals due to the test interface and DUT combined, in contrast to the measured signals due to the DUT alone. We will investigate the effects of the limited bandwidth, ringing, crosstalk, and reflection to the signaling and jitter degradation and establish a general model and method for quantifying waveform, eye-diagram, and jitter. Last, we will illustrate a new deconvolution based generic de-embedding method to remove the interface effects from the DUT measurements in terms of waveform, eye diagram, and jitter (DDJ and DDN).