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Josephson Junction Having Negative Resistance Characteristics

IP.com Disclosure Number: IPCOM000090966D
Original Publication Date: 1969-Sep-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Matisoo, J: AUTHOR

Abstract

This oscillator utilizes a Josephson junction device. The Josephson junction device in A consists basically of two metal contacts separated by a thin insulator held at cryogenic temperature in which pair tunneling occurs across the junction when a voltage is applied across the junction. A typical 1-V characteristic, is shown in B, obtained by measuring with a voltage source.

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Josephson Junction Having Negative Resistance Characteristics

This oscillator utilizes a Josephson junction device. The Josephson junction device in A consists basically of two metal contacts separated by a thin insulator held at cryogenic temperature in which pair tunneling occurs across the junction when a voltage is applied across the junction. A typical 1-V characteristic, is shown in B, obtained by measuring with a voltage source.

Oscillations can be obtained using the circuit of C under the following conditions. The Josephson junction device is connected to a voltage source which has a maximum voltage which is less than the voltage at point 3 in B. When the voltage source is connected to the junction, the current through the junction begins to build up from a zero value. Its rate of increase is limited only by the inductance of the circuit. Initially, since the junction is carrying a low current, it is in the zero voltage state and the current rises from zero toward 1 in
B. When the value I(g max) is reached, the junction rapidly switches to the high voltage state. Because the current is continuous due to nonzero inductance, the voltage at the junction jumps to 2. The voltage of the junction now opposes the current flow, causing the current to drop and the operating point to move toward
3. When the current drops to a given value I(g min), the junction switches back to the zero voltage state at point 4. The operation is repeated over and over as long as the...