Browse Prior Art Database

A High-Speed Differential Routing and Signaling Configuration with Impedance Compensation

IP.com Disclosure Number: IPCOM000077226D
Publication Date: 2005-Feb-25
Document File: 3 page(s) / 56K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that adds several holes (filled with different dielectric constant material) around the spacing-changed line in the differential trace. This compensates for differential impedance mismatching caused by a change of spacing between lines. Benefits include improved signal integrity and the ability to use current process and technology.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

A High-Speed Differential Routing and Signaling Configuration with Impedance Compensation

Disclosed is a method that adds several holes (filled with different dielectric constant material) around the spacing-changed line in the differential trace. This compensates for differential impedance mismatching caused by a change of spacing between lines. Benefits include

improved signal integrity and the ability to use current process and technology.

Background

Differential routing and signaling is a low noise, low power, low amplitude method for high-speed (i.e. gigabytes per second) data transmission over metal wire. General differential structures use a dual wire system that runs a signal 180 degrees from each other; this enables noise to travel at the same level so that it can be filtered more easily and effectively, enabling data travel over greater lengths of traces while maintaining a relatively clear and consistent signal. Differential circuit configuration is widely used and is becoming a dominant configuration for high-speed signaling and for low signal level applications.

The differential trace’s insensitivity to noise is based on a tight coupling between the trace. But in this situation of tight coupling, whenever a space of trace is changed the differential impedance changes so that sometimes a bad reflection occurs in system. A conventional way of avoiding differential impedance mismatching is to gradually change the distance of the pair of traces on a differential line. Also, lumped circuit components can be inserted, but these tend to impact high speed performance and increase the cost. Designers currently try to avoid these problem by using a loose coupled line to sacrifice the noise defendant character of the differential trace. In addition, a tight coupled line is used and the impedance mismatching is ignored, but this can cause signal integrity issues that can result in the malfunction of the system or circuit. In these situations, designers have no other solution but to accept impedance mismatch, or attempt to change routing layers.

General Description

The disclosed method adds several holes (filled with different dielectric constant material) around the spacing-changed line in the differential trace. This compensates for differential impedance mismatching caused by a change of spacing between lines. The disclosed method changes the dielectric constant...