Browse Prior Art Database

Reduction of Punchthrough in Josephson Latching Logic

IP.com Disclosure Number: IPCOM000050413D
Original Publication Date: 1982-Oct-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Anderson, CJ: AUTHOR

Abstract

In Josephson latching logic circuits, the phenomenon of punchthrough can occur when a logic element fails to reset to its zero voltage state during the transition of the power supply through zero. A technique for reducing the probability of punchthrough is described where the power supply regulator is biased in its resonances.

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Reduction of Punchthrough in Josephson Latching Logic

In Josephson latching logic circuits, the phenomenon of punchthrough can occur when a logic element fails to reset to its zero voltage state during the transition of the power supply through zero. A technique for reducing the probability of punchthrough is described where the power supply regulator is biased in its resonances.

The figure shows the circuit diagram of logic element 10, which is, for example, a three-junction Josephson element. A sine-wave input 12 is applied on line 14 and travels to a regulator circuit 16.

A clipped AC voltage waveform 18 is the output of regulator 16. Waveform 18 powers the logic element 10, which can be switched into the voltage state by a pulse on control line 20.

The superconducting current on the regulator is a function of the current in the control line 22 over the regulator. The output of the regulator and the output of the interferometer 10 can be sent to a Josephson sampling circuit for observation of the punchthrough probability. The minima in the punchthrough probability occur in the same regions of the regulator control current as the major resonances in the threshold curve of the regulator. The regions of the minimum punchthrough probability are not symmetric about zero regulator control current. However, there are some values of regulator control current that are in the minimum punchthrough probability regions for both polarities of power supply transition. By pro...