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Josephson and Gate with Tracking Current Inputs

IP.com Disclosure Number: IPCOM000050408D
Original Publication Date: 1982-Oct-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Gheewala, TR: AUTHOR [+3]

Abstract

In the Josephson technology, an AND gate includes OR devices, powered by an AC power supply, at the inputs to the current injection AND device. The injection device is not itself separately powered. The injection device and the symbol for it are shown in Fig. 1, as is its nominal threshold characteristic. I(A) and I(B) are the current inputs at nodes A and B of the device. The OR gates Q1 and Q2 are shown in the circuit of Fig. 2, along with the injection device 10. In order to improve the operating margins of the AND device, a circuit comprising Josephson junctions J1 and J2, together with shunt resistances R1 and R2, is used. This circuit tracks the inputs to the injection AND device.

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Josephson and Gate with Tracking Current Inputs

In the Josephson technology, an AND gate includes OR devices, powered by an AC power supply, at the inputs to the current injection AND device. The injection device is not itself separately powered. The injection device and the symbol for it are shown in Fig. 1, as is its nominal threshold characteristic. I(A) and I(B) are the current inputs at nodes A and B of the device. The OR gates Q1 and Q2 are shown in the circuit of Fig. 2, along with the injection device 10. In order to improve the operating margins of the AND device, a circuit comprising Josephson junctions J1 and J2, together with shunt resistances R1 and R2, is used. This circuit tracks the inputs to the injection AND device.

If the OR gates Q1 and Q2 have lower (or higher) current levels than the nominal design value, the operating point of the injection device 10 would be different from nominal and would thus affect the margins and operating characteristics of the device. To compensate for this, Josephson junctions J1 and J2, shunted by resistors R1 and R2, are placed in the circuit between the OR devices Q1 and Q2 and the injection device 10.

If the critical currents are high, J1 and J2 do not switch, and the resistance in each of the input lines is R(s). If the critical current levels are low, J1 and J2 will switch and thereby introduce resistors R1 and R2 into the input lines to injection device 10. This will keep the input currents to injection AND...