EXPERIMENTAL RESULTS ON SINGLE FLUX QUANTUM LOGIC

We have optimized the design and calculated the margins for a number of single flux quantum (SFQ) logic elements including AND, OR, XOR, Splitter, DC-to-SFQ converter, and SFQ-to-DC converter. These are the fundamental building blocks necessary to construct more complex logic functions such as the half adder, and full adder. Experimental tests of the primary gates, the AND, OR, XOR, and splitter, were made by imbedding each test gate between DC-to-SFQ converters at the inputs and SFQ-to-DC converters at the outputs. Automated testing of each circuit was used to determine functionality, optimum bias levels, and margins. The experimental bias current margins for each gate are consistent with the simulations. This is the first experimental functional confirmation of these SFQ logic gates.