New logic circuits based on SFQ signals

Abstract

We propose new logic circuits based on Single Flux Quantum logic with Resettable (SFQ-RL). This new logic enables us to initialize the whole circuit and realize an inverter easily. This initialization function is needed for general state machines, in addition, suppressing the failed operation caused by a trapped flux in storage loops. SFQ-RL logic consists of three primitives of gates, Latch (L)-gate, Copy(C)-gate and (O)-gate. L-gate is a kind of flip-flop gate. The difference from a conventional RSFQ latch, RS-FF is that L-gate can be reset without emitting an output pulse using Initialize pulse. Our numerical simulation shows that the bias margin of L-gate is /spl plusmn/8%. C-gate and O-gate correspond to Splitter and Confluence Buffer in RSFQ logic, respectively. Every logic function can be realized by only the three primitives. We confirmed the operations, AND and with reasonable margins and speeds by the numerical calculation. We have experimentally demonstrated the logic function such as OR based on SFQ-RL logic. We confirmed the normal operation of the gate with the bias margin of /spl plusmn/25.9%.