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Noise Reduction Scheme for MLC Packages

IP.com Disclosure Number: IPCOM000100015D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Haug, W: AUTHOR [+4]

Abstract

The described scheme can be easily implemented by wiring rules to drastically reduce delta I-caused noise of off-chip drivers without any drop in performance. By means of this scheme, the use of standard MLC packages may be extended to high-performance bus systems. The main idea on which it is based is a switching or wiring rule.

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Noise Reduction Scheme for MLC Packages

       The described scheme can be easily implemented by wiring
rules to drastically reduce delta I-caused noise of off-chip drivers
without any drop in performance.  By means of this scheme, the use of
standard MLC packages may be extended to high-performance bus
systems.  The main idea on which it is based is a switching or wiring
rule.

      Power and ground planes V1, 0V of multilayer ceramic (MLC)
carriers do not consist of solid metal planes but comprise dense
metal mesh planes which have a higher inductance than solid planes.
The inductance of the power or ground mesh plane between adjacent
chips is estimated to be of the order of approximately less than 0.1
nH.  If all drivers of the critical high-performance bus switch at
once, the maximum delta I current may reach values of about delta
I/delta t = 10 A/nsec.  The high AC current generates an induced
voltage drop at the inductance of the mesh plane of approximately 1
V.  This very high voltage drop leads to disturbance and malfunctions
of the chips, especially the receiving chip.

      The usual solutions of this problem are either to limit the
maximum number of simultaneous off-chip switching drivers or to slow
down the driver performance or to switch them in a time-staggered
fashion (in time slices) rather than all at once.  However, any of
these solutions adversely affect the system performance.

      The idea described in this article is to imple...