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US 7,397,320 B1Granted
Non-uniform transmission line for reducing cross-talk from an aggressor transmission line
AssigneeCadence Design Systems, Inc.
InventorSyed Asadulla Bokhari
Life of this patent
Estimating the term…
Abstract
A non-uniform transmission line, including at least a first section with length L1, uniform width W1 and thickness h1, and a second section with length L2, uniform width W2 and thickness h2, joined together to form a composite structure and arranged in any of at least three distinct configurations. The composite structure (first section plus second section) may be periodic or non-periodic. Length and/or width and/or thickness of each of the two sections may be varied to provide desired values for characteristic impedance, cutoff frequency and/or time delay for signal propagation.
Claims16
A non-uniform differential transmission line pair to reduce cross talk from an aggressor transmission line, the non-uniform differential transmission line pair comprising:
- a first transmission line on a first layer and a second transmission line on a second layer, each of the first transmission line and the second transmission line having
- a corresponding first transmission line section,
- a second transmission line section, and
- a third transmission line section,
- wherein the first transmission line section of each of the first transmission line and the second transmission line having a first end and a second end, having a first length L1, a first width W1 and a first line thickness h1, and containing an electrically conducting material,
- the second transmission line section of each of the first transmission line and the second transmission line having a first end and a second end, having a second length L2, a second width W2 and a second line thickness h2, and containing the electrically conducting material,
- the third transmission line section of each of the first transmission line and the second transmission line having a first end and a second end, having a third length L3, a third width W3 and a third line thickness h3, and containing the electrically conducting material,
- where the first end of each second section is joined to the corresponding second end of each first section and the first end of each third section is joined to the corresponding second end of each second section,
- where at least two of the following conditions are satisfied:
- the first length L1 is not equal to the second length L2, the first width W1 is not equal to the second width W2, and the first line thickness h1 is not equal to the second line thickness h2;
- a dielectric layer disposed between the first transmission line and the second transmission line, wherein the first transmission line and the second transmission line are positioned such that a quasi-twisted pair of transmission lines is effected with the first transmission line sections of the first and second transmission lines being in parallel and spaced apart by a selected transverse separation distance, the second transmission line sections of the first and second transmission lines being in parallel and overlapping each other, and the third transmission line sections of the first and second transmission lines being in parallel and spaced apart by the selected transverse separation distance;
- and
- a first ground plane over or under the first transmission line and the second transmission line.
10 more elements
An apparatus comprising:
- a non-uniform transmission line having a plurality of first transmission line sections and a plurality of second transmission line sections,
- the first transmission line sections having a first end and a second end, having a length L1, a width W1 and a line thickness h1, and containing a selected electrically conducting material having an electrical resistivity that is no greater than about 10−4 Ohm-cm,
- the second transmission line sections having a first end and a second end, having a length L2, a width W2 and a line thickness h2, and containing the selected material, where the first end of the second section is joined to the second end of the first section,
- wherein the width W2 of the second transmission line sections is greater than the width W1 of the first transmission line sections;
- a first ground plane of a finite size to substantially encompass the non-uniform transmission line and having a plurality of perforations, the first ground plane spaced apart and positioned symmetrically under and parallel to the non-uniform transmission line such that the plurality of perforations are directly under the non-uniform transmission line;
- a first dielectric layer disposed between the non-uniform transmission line and the first ground plane;
- a second ground plane under the first ground plane the second ground plane larger than the first ground plane to substantially encompass the non-uniform transmission line and the first ground plane;
- and
- a second dielectric layer disposed between the first ground plane and the second ground plane, wherein the second dielectric layer has one or more ground vias to connect opposite ends of the first ground plane to the second ground plane.
6 more elements
A method for transmission of an electromagnetic signal, the method comprising:
- providing an electromagnetic signal at a first end of a non-uniform transmission line and receiving the electromagnetic signal at a second end of the non-uniform transmission line, the non-uniform transmission line including
- a plurality of first transmission line sections having a first end and a second end, having a length L1, a width W1 and a line thickness h1, and containing a selected electrically conducting material having an electrical resistivity that is no greater than about 10−4 Ohm-cm,
- a plurality of second transmission line sections having a first end and a second end, having a length L2, a width W2 and a line thickness h2, and containing the selected material,
- wherein the first end of the second transmission line sections are joined to the second end of the first transmission line sections, and the width W2 of the second transmission line sections is greater than the width W1 of the first transmission line sections;
- providing a first ground plane of a finite size to substantially encompass the non-uniform transmission line and having a plurality of perforations, the first ground plane spaced apart and positioned symmetrically under and parallel to the non-uniform transmission line such that the plurality of perforations are directly under the non-uniform transmission line;
- providing a first dielectric layer disposed between the non-uniform transmission line and the first ground plane;
- providing a second ground plane under and parallel with the first ground plane, the second ground plane larger than the first ground plane to substantially encompass the non-uniform transmission line and the first ground plane;
- and
- providing a second dielectric layer disposed between the first ground plane and the second ground plane, wherein the second dielectric layer has one or more ground vias to connect opposite ends of the first ground plane to the second ground plane.
6 more elements
Dependencies are inferred from the claim text.