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Non-destructive Readout For Tunnel Diode Memory

IP.com Disclosure Number: IPCOM000098390D
Original Publication Date: 1960-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Myers, AS: AUTHOR

Abstract

The memory utilizes the high and low voltage states of a tunnel diode in conjunction with a variable capacitance diode to provide non-destructive readout.

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Non-destructive Readout For Tunnel Diode Memory

The memory utilizes the high and low voltage states of a tunnel diode in conjunction with a variable capacitance diode to provide non-destructive readout.

The basic storage cell (upper drawing) comprises a tunnel diode, which may be set in either a high or low voltage state by switching signals applied to terminals A-A. Across the tunnel diode is coupled a resonant circuit comprising inductor L1, variable capacitance diode C1 and capacitance C2. Capacitance C2 is much larger than the capacitance of the diode C1 and is used as a D.C. blocking element to prevent L1 from shorting out the D. C. voltage on C1. Since the tunnel diode is in either a low or high voltage state corresponding to a logical 0 and 1' respectively, the circuit including L1, C1, and C2 is resonant at one or the other of two given frequencies.

A radio frequency carrier source is coupled via coil L2 to the resonant circuit. The frequency of this source is selected to be equal to the frequency of the resonant circuit when the tunnel diode is in its 1 state. The output coil L3 is coupled to L1, but decoupled from L2. The parallel inductance resistance network between the tunnel diode and the tuned circuit decouples the switching signals applied to terminals A-A from the resonant circuit.

With the tunnel diode set in its 0 voltage condition, the resonant circuit is detuned from the frequency of the carrier source and little or no output is sensed at L3....