Browse Prior Art Database

Harper Cell With Improved Soft Error Immunity

IP.com Disclosure Number: IPCOM000040730D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Chin, WB: AUTHOR [+4]

Abstract

This disclosure describes a new Harper cell configuration that does not require the use of Schottky diodes to prevent saturation of the cell transistors. The new cell configuration is shown in the figure. The load resistors RL1 and RL2 are connected to a common resistor RT. The voltage drop from the word line to the base or collector in the cell is limited to 1 VBE by the clamp diodes D1 and D2 which are integrated in the collector bed of T1 and T2. The voltage drop across RT and RL will not exceed 1 VBE. With the proper choice of resistor values for RT and RL, the voltage drop across RL can be controlled to prevent the cell NPN transistor from being driven into saturation. When polysilicon is used for resistors RL and RT, the addition of RT has a minor impact on cell size.

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Harper Cell With Improved Soft Error Immunity

This disclosure describes a new Harper cell configuration that does not require the use of Schottky diodes to prevent saturation of the cell transistors. The new cell configuration is shown in the figure. The load resistors RL1 and RL2 are connected to a common resistor RT. The voltage drop from the word line to the base or collector in the cell is limited to 1 VBE by the clamp diodes D1 and D2 which are integrated in the collector bed of T1 and T2. The voltage drop across RT and RL will not exceed 1 VBE. With the proper choice of resistor values for RT and RL, the voltage drop across RL can be controlled to prevent the cell NPN transistor from being driven into saturation. When polysilicon is used for resistors RL and RT, the addition of RT has a minor impact on cell size. These clamp diodes D1 and D2 are chosen so that the diffusion capacitance is utilized for soft error immunity. This new cell configuration has the advantages of a Schottky- clamped Harper cell without using Schottky diodes and with less sensitivity to soft errors.

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