A Single-Clock Asynchronous Input COSL Set-Reset Flip-Flop and SFQ to Voltage State Interface

Although published research in COSL has stagnated, it remains a useful logic family for interfacing the much faster RSFQ family to hot-logic circuits. COSL has always been plagued by the absence of latches, and previous attempts at implementing such latches were clumsy. A new COSL Set-Reset flip-flop is discussed here, and results shown. This asynchronous input latch, which can also be configured as a T flip-flop, can function on a single-phase clock. It was also adapted to convert SFQ output pulses from RSFQ logic circuits to voltage state levels that can be viewed on standard laboratory oscilloscopes. Due to the asynchronous nature of the inputs, the RSFQ-COSL converter is also more reliable than earlier DRO-to-COSL elements.