Single flux quantum signal transmission techniques in building practical RSFQ circuits

Yamini Devi Ykuntam, Katta Pavani

Gleb Krylov, Eby G. Friedman

Boyko Dimov, Valery Todorov, Valeri Mladenov +1 more

An important precondition for the successful realization of any high-speed complex electronic device are the efficient (in terms of speed and signal degradation) long-distance interconnects. The two techniques for long-distance on-chip signal propagation, used by the modern rapid single flux quantum (RSFQ) designers - via Josephson transmission lines (JTLs) and via passive transmission lines (PTLs) - are investigated here. Novel design techniques are presented, which significantly improve the JTLs and PTLs performance as long-distance SFQ pulse transmitters within the digital RSFQ circuits.

Gleb Krylov, Tahereh Jabbari, Eby G. Friedman

Yuichi Yamazaki, Naoki Takeuchi, Nobuyuki Yoshikawa

Each superconductor logic family has distinct features and advantages. For instance, adiabatic quantum-flux-parametron (AQFP) circuits operate with very high energy efficiency, and rapid single-flux-quantum (RSFQ) circuits operate at very high clock frequencies. To build a hybrid system that combines the above advantages, we propose a compact interface between AQFP and RSFQ circuits that converts current signals in AQFP logic into flux signals in RSFQ logic using a non-adiabatic quantum-flux-parametron gate. Compared to a previously proposed AQFP/RSFQ interface, the proposed interface has far fewer Josephson junctions (4 vs. 11). We optimize the circuit parameters of the AQFP/RSFQ interface and demonstrate the interface at low speed as proof of concept. Furthermore, we demonstrate data propagation between AQFP circuits along a long passive transmission line via the AQFP/RSFQ interface at low speed to show that the AQFP/RSFQ interface can alleviate the interconnect length limit in AQFP circuits.

Pascal Febvre