Twelve Giga-Sample per Second Oscillator/Counter A/D Converter Demonstration

We describe recent demonstration of a superconductor oscillator/counter A/D Converter up through 12 GS/s with 3 effective bits of signal-to-noise ratio at that sample rate, along with analysis of its performance. Measurements are described for an A/D converter implemented in Northrop Grumman Space Technology's 4 kA/cm/sup 2/ J110D Niobium process. This A/D Converter incorporates a new technique for defining the aperture using inter-Josephson transmission line SFQ repulsion. This technique is described here.