Time-resolved liquid crystal voltage contrast. A new method for testing of digital integrated circuits

This paper deals with a new method for temporal resolved voltage contrast measurements of integrated circuits (IC) with nematic liquid cystals. It is shown, that the rms-behavior of the liquid chrystal can be exploited to perform sampled voltag contrast measurements with high temporal resolution. The determination of suitable measurement parameters is treated in detail and discussed by examples. The temporal resolution is limited by the ratio of threshold voltage and rms-value of the applied signal as well as the electro-optical transfer characteristic. Under suitable conditions we can show an absolute temporal resolution of better than 20nsec. This method leads to a direct timing analysis of digital states which is demonstrated by a simple circuit.