Browse Prior Art Database

Three Level Word Line Pulse for Single FET Cell Arrays

IP.com Disclosure Number: IPCOM000089227D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Gray, KS: AUTHOR

Abstract

Subthreshold leakage discharge of bit lines due to word line outcoupling of a stored bit of information in memory arrays employing a single field-effect transistor (FET)-capacitor cell is eliminated by utilizing a word line pulse having three different voltage levels.

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Three Level Word Line Pulse for Single FET Cell Arrays

Subthreshold leakage discharge of bit lines due to word line outcoupling of a stored bit of information in memory arrays employing a single field-effect transistor (FET)-capacitor cell is eliminated by utilizing a word line pulse having three different voltage levels.

As shown in Fig. 1, the single FET-capacitor cell array, which is described more fully in, e. g., U. S. Patent 3,387,286, has a first cell including an FET T1 coupling a storage capacitor CS1 to a bit line, such as the left bit line indicated in Fig. 1. Additional cells, such as the Nth cell having FET T2 and storage capacitor CSN, are coupled to the left bit line. The left bit sense line is coupled to an appropriate sense latch, and a right bit line is also connected to the same sense latch. An equal number of cells may be connected to the right bit line as are connected to the left bit line.

In the normal operation of the single FET cell, such as the first cell, when reading and when zero volts are stored on node VC1, a word pulse having a magnitude VH is applied to word line 1 to turn on T1. The left bit line, which had been precharged to VH minus a threshold voltage VT, initially discharges into node VC1 to lower the voltage on the left bit line, and then is discharged to ground by the sense latch in a well known manner. With the node VC1 at 0 volts, the relatively high voltage word pulse VH is now dropped to 0 volts. It can be seen that thi...