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DRAM With Latent Image - A Double Duty ROM And DRAM Array

IP.com Disclosure Number: IPCOM000099886D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 60K

Publishing Venue

IBM

Related People

Fang, FF: AUTHOR [+2]

Abstract

This article describes a new DRAM array design with an imbedded latent image. The design will provide two different functions: a dynamic RAM which can be initialized with a preset information pattern, like a ROM, and a dynamic random-access memory (DRAM) in the same array.

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This is the abbreviated version, containing approximately 76% of the total text.

DRAM With Latent Image - A Double Duty ROM And DRAM Array

       This article describes a new DRAM array design with an
imbedded latent image.  The design will provide two different
functions: a dynamic RAM which can be initialized with a preset
information pattern, like a ROM, and a dynamic random-access memory
(DRAM) in the same array.

      The simplest dynamic memory cell consists of a transistor (a
MOSFET switch) and a charge storage capacitor, as shown in Figs. 1
and 2.  The cell is connected to three array interconnection lines,
con sisting of the word line (connected to gate the electrode and the
bit line connected to the drain electrode), and the plate line
(connected to the upper capacitor electrode). The latent image is
generated by connecting each plate line to one of two different
buses.  To operate the array as a ROM (read-only memory), the latent
image must be written into the array.  For an n-channel array:
   (1) Select the chip and write zero volts ("0") to all the storage
nodes.
   (2) The plate lines are connected to two different buses. For
example, plate lines of the A cells are connected to a bus at 0 volts
(Fig. 3), and plate lines of the B cells are connected to a bus at
-10 volts (Fig. 4).
   (3) Switch the B cell plate line from -10 volts to 0 volts (Fig.
5).  After charge sharing, the voltage on the storage nodes of the B
cells will be equal to

                            (Image Omitted)

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