Method and device for transmission without crosstalk

• US 7,408,426 B2
• Filed: 02/18/2004
• Issued: 08/05/2008
• Est. Priority Date: 03/13/2003
• Status: Active Grant

• Current Assignee: S Aqua Semiconductor LLC (Intellectual Ventures LLC)
• Original Assignee: Zxtalk Assets LLC (Intellectual Ventures LLC)
• Inventors: Clavelier, Evelyne, Broyde, Frederic
• Primary Examiner(s): Pascal; Robert J.
• Assistant Examiner(s): Glenn; Kimberly E
• Application Number:
  US10/547,088
• Publication Number:
  US 20060192429A1
• Time in Patent Office: 1,630 Days
• Field of Search: 333/12, 333/100, 326/30, 345/58, 327/379, 327/551
• US Class Current: 333/100
• CPC Class Codes: H04B 3/32 Reducing cross-talk, e.g. by compensating

Abstract

The invention relates to a method and a device for transmission without crosstalk in interconnections used for sending a plurality of signals, such as the interconnections made with flat multiconductor cables, or with the tracks of a printed circuit board, or inside an integrated circuit. An interconnection with four parallel transmission conductors plus a reference conductor has each of its ends connected to a termination circuit. The transmitting circuit receives at its input the signals of the four channels of the source and its output terminals are connected to the conductors of the interconnection. The receiving circuit(s) input terminals are connected to the conductors of the interconnection, and its four output channels are connected to the destination. The signals of the four channels of an active source are sent to the four channels of the destination, without noticeable crosstalk.

Claims

1. A method for transmitting through an interconnection with n transmission conductors and a reference conductor, n being an integer greater than or equal to 2, the method providing, in a known frequency band, m transmission channels each corresponding to a signal to be sent from an input of at least one transmitting circuit to an output of at least one receiving circuit, where m is an integer greater than or equal to 2 and less than or equal to n, the method comprising the steps of:

proportioning the interconnection, taking into account lumped impedances seen by the interconnection and caused by circuits connected to the interconnection elsewhere than at the ends of the interconnection, so as to be able to model the interconnection as a multiconductor transmission line having uniform electrical characteristics over the length of the multiconductor transmission line for the known frequency band, the electrical characteristics being such that propagation constants of different propagation modes are substantially equal in the known frequency band;

determining a characteristic impedance matrix of the multiconductor transmission line in the known frequency band;

placing at both ends of the interconnection a termination circuit having an impedance matrix approximating the characteristic impedance matrix,

using one of the transmitting circuits to which m input signals are applied, so as to obtain at an output of said one of the transmitting circuits, the output being connected to at least m transmission conductors among the transmission conductors the generation of natural electrical variables, each being proportional to one of the input signals; and

using one of the receiving circuits, the input of which is connected to at least m transmission conductors among the transmission conductors, so as to obtain, at the output of said one of the receiving circuits, m output signals each corresponding to one of the transmission channels, each of the m output signals being proportional to a single natural electrical variable among said natural electrical variables.

2. The method of claim 1, wherein said natural electrical variables are either all voltages or all electric currents.

3. A device for proportioning circuits used in a method for transmitting through an interconnection with n transmission conductors and a reference conductor, n being an integer greater than or equal to 2, the method providing, in a known frequency band, m transmission channels each corresponding to a signal to be sent from an input of at least one transmitting circuit to an output of at least one receiving circuit, where m is an integer greater than or equal to 2 and less than or equal to n, the device comprising:

means for proportioning the interconnection, taking into account lumped impedances seen by the interconnection and caused by circuits connected to the interconnection elsewhere than at the ends of the interconnection, so as to be able to model the interconnection as a multiconductor transmission line having uniform electrical characteristics over the length of the multiconductor transmission line for the known frequency band, the electrical characteristics being such that propagation constants of different propagation modes are substantially equal in the known frequency band;

means for determining a characteristic impedance matrix of the multiconductor transmission line in the known frequency band;

means for proportioning a termination circuit having an impedance matrix approximating the characteristic impedance matrix;

means for proportioning one of the transmitting circuits to which m input signals are applied, so as to obtain at an output of said one of the transmitting circuits, the output being connected to at least m transmission conductors among the transmission conductors, the generation of natural electrical variables, each being proportional to one of the input signals; and

means for proportioning one of the receiving circuits, an input of which is connected to at least m transmission conductors among the transmission conductors'"'"' so as to obtain at the output of said one of the receiving circuits, m output signals each corresponding to one of the transmission channels, each of the m output signals being proportional to a single natural electrical variable among said natural electrical variables.

4. The device of claim 3, wherein the means for portioning the interconnection comprise means for measuring and/or for computing the real electrical characteristics of the interconnection, based on the relative layout of the transmission conductors end the reference conductor, and on the characteristics of dielectrics surrounding them.

5. The device of any of the claim 3, wherein the means for modeling the interconnection comprise:

means for calculating one or more error coefficients for variance between the actual electrical characteristics of the interconnection and desired characteristics, for the known frequency band, and

means for optimizing the relative position of the transmission conductors and/or dielectrics surrounding them, by minimizing the error coefficient or coefficients.

6. A device for transmission providing, in a known frequency band, m transmission channels each corresponding to a signal to be sent from an input of at least one transmitting circuit to an output of at least one receiving circuit, where m is an integer greater than or equal to 2, the device comprising:

an interconnection with n transmission conductors and a reference conductor, being an integer greater than or equal to m, the interconnection being proportioned in such a way that the interconnection, taking into account lumped impedances seen by the interconnection and caused by the circuits connected to the interconnection elsewhere than at the ends of the interconnection, is modeled as a multiconductor transmission line having uniform electrical characteristics over the length of the multiconductor transmission line for the known frequency band, the electrical characteristics being such that propagation constants of different propagation modes are substantially equal in the known frequency band;

two termination circuits, each arranged at a different end of the interconnection and each having, in the known frequency band, an impedance matrix approximating a characteristic impedance matrix of the multiconductor transmission line;

at least one of the transmitting circuits to which the m input signals are applied, so as to obtain at the output of said one of the transmitting circuits, the output being connected to at least m transmission conductors among the transmission conductors'"'"' the generation of natural electrical variables, each being proportional to one of the input signals; and

at least one of the receiving circuits, an input of which is connected to at least in transmission conductors among the transmission conductors, so as to obtain, at the output of said one of the receiving circuits, m output signals each corresponding to one of the transmission channels, each of the m output signals being proportional to a single natural electrical variable among said natural electrical variables.

7. The device of claim 6, wherein said natural electrical variables are either all voltages or all electric currents.

8. The device of claim 6, wherein the generation of the natural electrical variables is obtained at the output of the at least one transmitting circuit.

9. The device of claim 6, wherein the number m of transmission channels between any one of the transmitting circuits and any one of the receiving circuits is equal to the number n of transmission conductors.

10. The device of claim 6, wherein linear combinations of signals are performed in at least one of the transmitting circuits and/or in at least one of the receiving circuits, using an analog processing.

11. The device of claim 6, wherein linear combinations of signals are performed in at least one of the transmitting circuits and/or in at least one of the receiving circuits, using a digital processing.

12. The device of claim 11, wherein the digital processing performed in the at least one transmitting circuit and/or the digital processing performed in the at least one receiving circuit are defined by a program.

13. The device of claim 6, wherein the termination circuits are made of a network of resistors.

14. The device of claim 6, wherein the effects of distortions caused by propagation are reduced by an equalization implemented in at least one of the transmitting circuits and/or one of the receiving circuits, on one or more of the transmission channels.

15. The device of claim 6, wherein an adaptive equalization is implemented in at least one of the receiving circuits, for one or more of the transmission channels.

16. The device of claim 6, wherein the interconnection is operated as a data bus.