SUNY RSFQ Cell Library

SFQ Pulse Splitter

Schematics

All parameters are in PSCAN dimensionless units .

This element produces two SFQ pulses (one on each output) for each incoming pulse.

Mealey Machine

FSM

How It Works

An input SFQ pulse switches junction J1, which in turn switches both J2 and J3 producing two pulses on two outputs.

The parameters of this cell were calculated to make it work like an amplifying JTL segment. The input junction J1 is Sqrt(2) times larger than the standard JTL junctions. It drives two junctions of value 2, the sum of their critical currents is again Sqrt(2) times larger than J1. The inductance L1+(L2||L3) with the value of 0.75 units is exactly what is needed to drive a "junction" with critical current 4.

Power supply current and inductance ratios are chosen to bias all junctions to the "standard" value of 0.7 of their critical currents.

The delay of this splitter is about 10 time units.

One can cascade any number of these splitters together (e.g., to build a clock distribution tree) without margins degradation.

View online the files necessary to simulate the circuit with Julia or download the whole compressed directory.

This cell was optimized for interconnectivity to be a part of cell library.

Transient Waveforms

Waveforms

Layout

Layout Photo

References

O. A. Mukhanov, V. K. Semenov, and K. K. Likharev, "Ultimate performance of the RSFQ Logic Circuits," IEEE Trans. Magn., vol. MAG-23, No. 2, pp. 759-762, Mar. 1987.
K. Likharev and V. Semenov, "RSFQ logic/memory family: A new josephson-junction technology for sub-terahertz clock-frequency digital systems", IEEE Trans. Appl. Supercond., vol. 1, pp. 3-28, March 1991.

The way to calculate the splitter parameters in such a way that it looks like a JTL segment was suggested to me by V. Semenov.

Paul BUNYK

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