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Word Line Voltage Clamp

IP.com Disclosure Number: IPCOM000075942D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Geller, H: AUTHOR [+5]

Abstract

This word-clamp establishes the maximum voltage to which a word line VT of a monolithic memory circuit can be powered up when fully selected. This is done to prevent significant forward bias of the resistor-to-bed PN junction of a number of cell collector resistors RC1, RC2 attached to word line VT.

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Word Line Voltage Clamp

This word-clamp establishes the maximum voltage to which a word line VT of a monolithic memory circuit can be powered up when fully selected. This is done to prevent significant forward bias of the resistor-to-bed PN junction of a number of cell collector resistors RC1, RC2 attached to word line VT.

The cell collector resistors RC1, RC2 are in an N-type bed which is biased at
2.15 volts for power and leakage reasons. The word line VT must be driven by a voltage higher than 2.15 volts in order to meet performance requirements. However, if the resistor-to-bed junctions are forward biased a large PN diode capacitance results. When this happens, recovery between cycles becomes a problem.

This word-clamp was designed to resolve the above problem. The added circuitry takes up negligible chip area because only one clamp is needed. Both outputs WO, WO of one true-complement generator are clamped. One or the other of these outputs WO, WO goes to every word decode and driver. The word-clamp operates in the following manner. The collector of the off transistor in the true-complement generator is charged up toward the supply voltage (3.7 volts). However, the output will be clamped at slightly more than 2.15 volts. This limits the rise of the base voltage of the word-driver transistor T1. The emitter of T1 (the word line) is held at the same voltage as the true-complement generator output.

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