Lissajous Based Mixed-Signal Testing for N-Observable Signals

A methodology for enhanced Lissajous based test (LBT) using n observable signals of the circuit under test (CUT) is proposed. This cost effective approach to mixed-signal testing relies on the fact that the "shape" of the curve generated by the composition of n circuit signals is sensitive to a large class of CUT catastrophic and parametric defects. The Rfrⁿobservation space is partitioned into zones using hyper-planes identified with a digital code. The number of zone crossings generates a set of digital signatures when the circuit is excited by a periodic multi-tone signal. The viability of this test approach, taking into account noise and tolerable parametric shifts due to technology variations, is analyzed. Preliminary results obtained with an experimental set-up on a biquad filter are encouraging