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Delay Line for Use with Integrated Circuits

IP.com Disclosure Number: IPCOM000093045D
Original Publication Date: 1967-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Brennan, PA: AUTHOR [+3]

Abstract

This structure obtains large delays per unit length of a strip transmission line. A high, effective dielectric constant is obtained using a two-layered medium between the transmission line conductors. The dielectric constant of each layer is much lower than the resulting effective dielectric constant. An optimum delay is obtainable and variations from the optimum are obtained by changing the ratio of the thicknesses of the two layers. The relatively large delays result from the generation of a surface wave mode in the upper of the two dielectrics when proper conditions of resistivity and dielectric constant are met in the lower dielectric layer. This latter layer can be a semiconductor such as silicon or germanium.

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Delay Line for Use with Integrated Circuits

This structure obtains large delays per unit length of a strip transmission line. A high, effective dielectric constant is obtained using a two-layered medium between the transmission line conductors. The dielectric constant of each layer is much lower than the resulting effective dielectric constant. An optimum delay is obtainable and variations from the optimum are obtained by changing the ratio of the thicknesses of the two layers. The relatively large delays result from the generation of a surface wave mode in the upper of the two dielectrics when proper conditions of resistivity and dielectric constant are met in the lower dielectric layer. This latter layer can be a semiconductor such as silicon or germanium.

The structure can be treated as a form of strip transniission line in which the line of width W is supported by a two-material medium. The thicknesses of the two layers are denoted by l(1) and l(2) while oi &i and mu(i), where i = 1, 2, represent the conductivity, relative permittivity, and relative permeability, respectively, of these layers. The fundamental mode of this structure is an E mode which is a surface wave. Its longitudinal propagation constant is approximated by

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