Browse Prior Art Database

Decoded Isolation Device for Decoders

IP.com Disclosure Number: IPCOM000042574D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Ellis, WF: AUTHOR

Abstract

A multiple bit/word line driving decoder is disclosed in which the gate of a bootstrap isolation device associated with an unselected decoder is discharged prior to the arrival of a drive pulse. By pulling the unselected isolation devices to ground, the associated (i.e., unselected) bit/word lines are effectively clamped.

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Decoded Isolation Device for Decoders

A multiple bit/word line driving decoder is disclosed in which the gate of a bootstrap isolation device associated with an unselected decoder is discharged prior to the arrival of a drive pulse. By pulling the unselected isolation devices to ground, the associated (i.e., unselected) bit/word lines are effectively clamped.

This result is achieved without adding a load to the bit/word lines or materially decreasing available chip space. In high density dynamic RAMs, signal margins are being reduced as geometrically smaller cells and sense-amps are developed. One of the functions the sense-amp performs is the selection of specific RAM devices within the memory array. The present bit/word decoder selects which one of a plurality of bit/word lines is to be activated and clamps the unselected lines to ground while allowing the selected line to receive a drive signal. With reference to the drawing, the VW (or primary word) decoder receives signals WST/C 1 and 2, which are the least significant address outputs of a word address (or T/C) generator (not shown). The decoder responds to the address input signal to set the states of four primary word signals VW1-VW4 and four isolation signals VRW1-VRW4. Thus, during a subsequent store/refresh operation, one of the bootstrap isolation gates T2, T4, T8 and T10 will remain high while the rest will be discharged. At that time, the VW signal that corresponds to the high VRW signal will rise, while the other three VW's and VRW's will be clamped to ground. For example, assume that WL1 is to be activated. The WST/C 1 and 2 signals will set the gate T2 (VRW1) high while VRW2-4 are set to ground. At the same time, signals VW2-4 will be clamped to ground, causing word lines WL2-4 to be clamped to ground through devices T6, T9...