Browse Prior Art Database

Variable On Chip Delay Line with Josephson Devices

IP.com Disclosure Number: IPCOM000045346D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Kaplan, SB: AUTHOR

Abstract

Delay lines which provide a variable delay are useful in many types of circuits, including fast measurement circuits. In the Josephson device technology, such a delay line having a variable delay depending upon the application of a quasi-DC bias is very useful. This type of delay line is provided in an on-chip embodiment in which part of the transmission line inductance is replaced with Josephson devices.

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Variable On Chip Delay Line with Josephson Devices

Delay lines which provide a variable delay are useful in many types of circuits, including fast measurement circuits. In the Josephson device technology, such a delay line having a variable delay depending upon the application of a quasi-DC bias is very useful. This type of delay line is provided in an on-chip embodiment in which part of the transmission line inductance is replaced with Josephson devices.

Josephson devices, including weak links, tunnel junctions, microbridges, variable thickness or proximity-effect bridges, have a parametric inductance which is a function of the bias current through the device. By varying this bias, the small signal parametric inductance will be changed, resulting in a variable LC delay.

In the embodiment shown, a Josephson device makes up the major part of the inductance of each stage of the transmission line 10. The input signal is applied between terminals A and C, while the bias current I(B) is applied between terminals A and B. The output is measured between terminals B and D. The expected delay is approximately n (2L(S)+L(J))C , where n is the number of stages, L(S) is the series inductance which is not part of the Josephson elements, and C(p) is the capacitance of each stage between top and bottom transmission line electrodes.

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