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A pipelined 8-bit-serial single-flux-quantum (SFQ) microprocessor, called CORE1β, was designed and tested. The CORE1β has two cascaded arithmetic logic units (ALUs) based on forwarding architecture, which can perform two register operations from one instruction. Pipelining is also extensively adopted to enhance the performance. A new design method, known as one-hot encoding, has been introduced into the design of the control circuit. The 4-stage-pipelined SFQ microprocessors, CORE1β8, have been implemented using the CONNECT cell library and the SRL 2.5 kA/cm2 Nb process. The frequency for the instruction fetch is 25 GHz, and 20 GHz for the bit-serial data operation. The peak performance and the power consumption of the CORE1β8 are estimated to be 1400 MOPS (million instructions per second) and 3.4 mW, respectively. We have experimentally demonstrated 4-stage pipelining and all functionalities of the CORE1β8 microprocessors by on-chip high-speed tests. [ABSTRACT FROM AUTHOR]

We have been investigating a design methodology of SFQ logic circuits based on the binary decision diagram (BDD). In the previously proposed BDD SFQ logic circuits, we have used one-to-two binary switches as a node cell in a BDD tree. In this study we will propose a new implementation method of SFQ BDD circuits, in which two nodes are implemented by using a 2-input 2-output switch gate. By employing the new approach, we have designed and implemented a one-bit full adder using the NEC 2.5 kA/cm² Nb standard process and the CONNECT cell library. The maximum operating frequency of the full adder was found to be 40 GHz by circuit simulations and 32.8 GHz by on-chip high- speed tests. [ABSTRACT FROM AUTHOR]