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Sense Amplifier for Niobium Oxide Switchable Resistor

IP.com Disclosure Number: IPCOM000077300D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Herrell, DJ: AUTHOR

Abstract

Niobium oxide switchable resistors (NOSR) have a high-impedance state which varies anywhere between 20 k ohm and 500 k ohm, being typically 80 k ohm. A low-impedance state of the device varies from 1 k ohm to 6 k ohm, and is typically 2.5 k ohm. The circuit above is used to differentiate between these two impedance states. It is a sense circuit having a "crossover" at approximately 10 k ohm.

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Sense Amplifier for Niobium Oxide Switchable Resistor

Niobium oxide switchable resistors (NOSR) have a high-impedance state which varies anywhere between 20 k ohm and 500 k ohm, being typically 80 k ohm. A low-impedance state of the device varies from 1 k ohm to 6 k ohm, and is typically 2.5 k ohm. The circuit above is used to differentiate between these two impedance states. It is a sense circuit having a "crossover" at approximately 10 k ohm.

A nonlinear (diode) sense element is followed by a differential amplifier, in this case a pair of connected transistors. An interrogate pulse from source 10 is applied to the NOSR device 12, the device in this case having a Bi counter electrode and an Nb base electrode. Transistor T1 has its base and collector electrically connected and the voltage Vc at the collector of T1 will vary approximately logarithmically with the conductance of NOSR 12, for impedances in the range 500 ohms - 500 k ohms. Vc is typically 0.05 volt (Vin/2) for NOSR resistance of 10 k ohms, the precise calibration depending upon the characteristics of T1.

A sense amplifier comprises transistors T2 and T3 which are coupled together. The output of the amplifier is taken off the collectors of T2 and T3. This circuit will provide adequate differentiation between the low and high- impedance states of device 12.

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