Microcircuit analysis techniques using field-effect liquid crystals

New analysis methods are described which use the non-destructive field-effect liquid-crystal display (LCD) technique to produce a static optical display of circuit node logic levels associated with selectable digital states of an operating integrated circuit (IC). One method employs special control of the device under test (DUT) and another uses a synchronous, externally applied electric field to produce either a two-state comparison display or a single-state display. The DUT is operated in a repeating test cycle consisting of a sequence of states for both techniques. Application details are discussed and typical analysis results are presented for a variety of circuit functions and LSI chip technologies.