Browse Prior Art Database

Current Amplifier with no Multiple Looping of Control Current Line

IP.com Disclosure Number: IPCOM000089402D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Faris, SM: AUTHOR

Abstract

Conventional current amplifications can be obtained by providing control current I(c) in loops over a Josephson device. A number of loops may be required to switch the device and thereby transfer current to a load. It is inevitable that the larger the required gain, the more loops are needed to obtain it. The multiplicity of loops is reflected in large inductance which slows down the operation of the device.

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Current Amplifier with no Multiple Looping of Control Current Line

Conventional current amplifications can be obtained by providing control current I(c) in loops over a Josephson device. A number of loops may be required to switch the device and thereby transfer current to a load. It is inevitable that the larger the required gain, the more loops are needed to obtain it. The multiplicity of loops is reflected in large inductance which slows down the operation of the device.

However, current amplification may be obtained by combining Josephson gates and resistors in circuit 1 shown in the above figure, thus eliminating multiple looping. Devices Q(1), Q(2) and Q(3) may be single Josephson junctions, multiple junction interferometers, or a combination thereof. Because of resistors R(Q1), R(Q2) and R(Q3), gate current I(g) can be larger than the threshold current I (mo) of the gates. Its upper limit is determined by the tolerances of the elements constituting circuit 1.

The operation of the amplifier of circuit 1 relies on total transfer of gate current I(g) to a load Z(L) by switching only device Q(1) upon application of the control current, I(c), to control line 2. I(Q1) is then diverted to devices Q(2) and Q(3), causing I(Q2) and I(Q3) to increase until I(mo2) and I(mo3) are exceeded, resulting in the switching of both devices Q(2) and Q(3). With devices Q1-Q3 switched, I(g) is now transferred to load Z(L). As an example, if I(mo1) = I(mo2) = I(mo3) = 2mA and R(Q1...