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Six-device Memory Cell With Active Write Discharge

IP.com Disclosure Number: IPCOM000099506D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 68K

Publishing Venue

IBM

Related People

Wong, RC: AUTHOR

Abstract

A circuit configuration using base collector junctions as active write discharge diodes is proposed to enhance the performance of saturated cells in semiconductor devices. The sharing of a load device as the active discharge device will provide significant improvements in density and power requirements.

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Six-device Memory Cell With Active Write Discharge

       A circuit configuration using base collector junctions as
active write discharge diodes is proposed to enhance the performance
of saturated cells in semiconductor devices. The sharing of a load
device as the active discharge device will provide significant
improvements in density and power requirements.

      The write performance of saturated cells is improved with the
use of various active diode discharge schemes.  In those previously
proposed, eight or more devices are needed. This requires large cell
sizes, and the new configurations may lead to new defects.

      This proposal suggests that active discharge may be
accomplished with a conventional six-device cell with isolated PNP
load and Schottky barrier diode (SBD) couplings (Fig. 1).  PNP loads
have previously been used in bipolar arrays for density, power
saving, and performance reasons. In the suggested configuration, the
PNP base collector junctions are also utilized as the active write
discharge diodes.

      The dual utilization of the collector junctions is achieved by
isolating the PNPs from the cross-coupled NPNs. Even though they are
on separate subdiffusion beds, some integration is still possible
through the use of P+ PolySi runners.  Multiple PNPs may also share a
common emitter and all PNPs of the same row can share a common N+
subdiffusion bed.  These configurations have no, or little, negative
effect on the density of th...