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Arrangement for More Accurately Measuring WI Noise

IP.com Disclosure Number: IPCOM000036019D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 78K

Publishing Venue

IBM

Related People

Klink, E: AUTHOR [+4]

Abstract

The electrical limits of single and multi-chip modules are presently determined by the WI noise. This is an inductive voltage drop on the chip and substrate wiring which is caused by many off-chip driver transistors (up to 100) or on-chip logic means (1000 to 2000 SR latches) switching simultaneously. (Image Omitted)

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Arrangement for More Accurately Measuring WI Noise

The electrical limits of single and multi-chip modules are presently determined by the WI noise. This is an inductive voltage drop on the chip and substrate wiring which is caused by many off-chip driver transistors (up to 100) or on-chip logic means (1000 to 2000 SR latches) switching simultaneously.

(Image Omitted)

By measuring the WI noise, a relatively inaccurate result is obtained, because such measuring is effected close to chip 1a (left part of Fig. 1), for multilayer ceramic substrates 2 at an EC pad 3, with reference point 4 being positioned on card 5. As a result, the hatched measuring loop 6 is relatively large and the measuring result correspondingly inaccurate. By introducing a reference grid 7 (Fig. 2) on the substrate surface, the hatched measuring loop 8 (right part of Fig. 1) is greatly reduced.

Fig. 1 additionally shows by means of chip 1b how the internal chip measuring line is led across a chip pad 9, through a module via and the signal wiring system 10 to an EC pad 11 on the substrate surface. This pad is contacted by a probe 12. Probe ground 13 is positioned on reference grid 7 close to the EC pad 11 (Fig. 2). The ground potential is connected through many vias, following the shortest path, to voltage level 15, the connecting points being chosen such that the falsification by operating currents is reduced to a minimum. The measuring loop thus produced on the substrate is very accurately defi...