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Harper Cell Read Reference Circuit

IP.com Disclosure Number: IPCOM000085044D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 92K

Publishing Venue

IBM

Related People

Dennison, RT: AUTHOR [+3]

Abstract

A Harper (multiemitter) cell read operation utilizes a reference voltage which in magnitude is approximately midway between the internal cell node potentials. This reference potential is usually a constant value during a read operation and is switched "off" during a write operation. However, more efficient operation of an array results if the reference source follows the "controlling" word line, i.e., the most positive word line at any given point in time.

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Harper Cell Read Reference Circuit

A Harper (multiemitter) cell read operation utilizes a reference voltage which in magnitude is approximately midway between the internal cell node potentials. This reference potential is usually a constant value during a read operation and is switched "off" during a write operation. However, more efficient operation of an array results if the reference source follows the "controlling" word line, i.e., the most positive word line at any given point in time.

The circuit depicted in Fig. 1 generates a reference voltage which is midway between the internal node potentials (nodes A and B) of the cells connected to the most positive (selected) word line.

The reference voltage follows the dotted line labeled "vs" in Fig. 2.

A brief description of the circuit operation follows.

Assume 16 decode circuits, only the first and second of which are expressly shown in Fig. 1. The one decoder of the 16 which has all inputs UP is selected. Each decoder is connected to two drivers.

One driver powers one out of the 16 word lines (WA, WB, etc.) for cell selection, while the other drives a common-emitter OR dot line (WS) for the reference cell.

Since the bases of the transistors of the two selected drivers are physically a common point, the selected word line and the common-emitter dot line WS are essentially at the same potential.

Node WS is controlled by the most positive decoder circuit output. Thus, during word line switching (changing to a new...