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Memory Diode Array Circuit

IP.com Disclosure Number: IPCOM000076718D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Cavaliere, JR: AUTHOR [+2]

Abstract

This circuit stores binary data in an array of MxN memory diodes. This array circuit can be built as an integrated circuit on a semiconductor chip. The array is similar to a conventional diode read-only memory, but it is also electrically writeable.

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Memory Diode Array Circuit

This circuit stores binary data in an array of MxN memory diodes. This array circuit can be built as an integrated circuit on a semiconductor chip. The array is similar to a conventional diode read-only memory, but it is also electrically writeable.

The memory diode MD has two states: A diode state and a high-resistance state. Either state is stable with power off for long periods of time. The voltage - current characteristics of the two states are shown in Fig. 1. Switching from the diode state to the high-resistance state is accomplished with a circuit load-line intersecting only the high-resistance state and vice versa. The switching load- lines are provided by the array circuit shown in Fig. 2.

A memory diode is selected for a read or write operation by the intersection of a selected row line with a selected column line. A row line is selected when its row line driver (T2K, R2K, R3K, 1 </- K </- N) input (IK, 1 </- K </- N) is at the high-voltage level and all other row driver inputs IK are at the low voltage level. One out of M column current switch (T3J, 1 </- J </- M) inputs (SJ, 1 </- J </- M) is at the high-voltage level. The other column current switch inputs SJ are at the low-voltage level. The column current will therefore be switched into the selected column. The column current will flow through either the selected memory diode MD or through the column sense transistor (T1J, 1 </- J </- M) depending on the state of the selected memory diode. The presence or absence of the column current at the data output indicates the state of the selected diode.

Circuit inputs WD and WH control the write operation. To write the selected memor...