Browse Prior Art Database

CROSS-TALK SUPPRESSION WITH CONCENTRIC GUARD RINGS

IP.com Disclosure Number: IPCOM000007435D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2002-Mar-26
Document File: 2 page(s) / 85K

Publishing Venue

Motorola

Related People

Kuntal Joardar: AUTHOR [+3]

Abstract

A technique for reducing cross-talk between dif- ferent circuit sections in an integrated circuit (IQ through the conductive silicon substrate, is described. The technique uses a set of concentric guard rings around the source and sensor of cross-talk in a man- ner that allows reduction of overall die size of the IC.

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6% MmROLA V Technical Developments

CROSS-TALK SUPPRESSION WITH CONCENTRIC GUARD RINGS

by Kuntal Joardar, Pam Welch and Jenny Ford

  A technique for reducing cross-talk between dif- ferent circuit sections in an integrated circuit (IQ through the conductive silicon substrate, is described. The technique uses a set of concentric guard rings around the source and sensor of cross-talk in a man- ner that allows reduction of overall die size of the IC.

  For illustration two circuits fabricated on a com- mon p-type silicon substrate is considered. When circuit A is in operation it generates voltage tran- sients that are coupled to the substrate. Circuit A is referred to as the cross-talk source. The transients generated by circuit A travel through the substrate and are felt by the second circuit, B, which is located at a finite distance From A. If these transients are large enough they may prevent the proper operation of circuit B. Circuit B is referred to as the cross-talk sensor.

  To reduce the amount of cross-talk between the two circuits described above, a ring of heavily doped p-type material is placed around each circuit, as shown in Figure 1. These heavily doped p-type rings

are referred to as guard rings. The guard rings are electrically connected to ground and help reduce cross-talk by absorbing the transients generated by the cross-talk source.

  To reduce cross-talk to suhiciently low levels using a single guard ring around the source and the sen- sor, as shown in...