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Bistable Memory

IP.com Disclosure Number: IPCOM000098434D
Original Publication Date: 1960-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Slobodzinski, EJ: AUTHOR

Abstract

A non-destructive readout memory consists of a bistable electric cell having a voltage-current relationship characterized by a negative resistance region between two positive resistance regions. It is further characterized in that the second derivatives (or rates of change of slope) of the positive resistance regions are opposite in sign, the cell being stable in either of its positive resistance regions. The Esaki or tunnel diode is such a device. Readin is effected by switching the cell from one of its stable states to the other. Readout is achieved by applying an alternating current readout voltage across the cell and by a sensing device responsive to harmonic current through the cell.

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Bistable Memory

A non-destructive readout memory consists of a bistable electric cell having a voltage-current relationship characterized by a negative resistance region between two positive resistance regions. It is further characterized in that the second derivatives (or rates of change of slope) of the positive resistance regions are opposite in sign, the cell being stable in either of its positive resistance regions. The Esaki or tunnel diode is such a device. Readin is effected by switching the cell from one of its stable states to the other. Readout is achieved by applying an alternating current readout voltage across the cell and by a sensing device responsive to harmonic current through the cell.

In the lower drawing a tunnel diode 10 and a resistor 11 are series connected. The resistor 11 serves as a load for the diode 10 and has a preselected value RL determinable by design considerations such that the diode is stable at points A and B.

Readin to the memory cell is effected by the selective application of voltage sources 13 and 14 to the cell 10 through switch 12. Nondestructive readout is accomplished by applying an A. C. voltage difference across the cell by means of source 15 and switch 16. The readout is detected by a sensing circuit 17 such as a phase discriminator.

Application of the alternating potential generates a second harmonic having a given phase when in Region I and the opposite phase when in Region III. Those phases define the 0 and 1 sta...