Area Efficient Asynchronous SFQ Pulse Round-Robin Distribution Network

We present an area-efficient, asynchronous, single-input, and multiple-output Rapid Single Flux Quantum (RSFQ) pulse round-robin distribution network. We adopt the structure of a two-output toggle flip flop (TFF) where incoming pulses are temporarily stored in a SQUID loop in the form of magnetic flux quanta and then directed to outputs in a round-robin fashion. To support additional toggle outputs, we design a new circuit based on TFFs to distribute pulses in a round-robin mechanism to more than two outputs. We also elaborate on our design methodology that can support a different number of outputs while minimizing the number of JJs and power consumption. We then demonstrate a three- and four-output round-robin distribution network constructed with only 14-JJs and 18-JJs with <inline-formula> <tex-math notation="LaTeX">$14.85 ~\mu W$ </tex-math></inline-formula> and 18.86-<inline-formula> <tex-math notation="LaTeX">$\mu W$ </tex-math></inline-formula> power dissipation, respectively. Our four-output design has 40%–70% fewer JJ compared to a similar-functioning four-output network composed of TFFs, DFFs, splitters, and mergers. Our design also consumes 38%–70% less power and has a 16%–64% reduced delay compared to the same four-output TFF network. Finally, we demonstrate the usability of our four-output design in the context of a periodic counting network and pulse generator.