Method and device for transmission with reduced crosstalk

A device for proportioning the 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 the input of at least one transmitting circuit to the 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 modeling the interconnection, taking into account the lumped impedances seen by the interconnection and caused by the circuits connected to the interconnection elsewhere than at the ends of the interconnection, as a multiconductor transmission line having uniform electrical characteristics over its length for the known frequency band;
• means for determining, for the multiconductor transmission line and the known frequency band, the characteristic impedance matrix and a transition matrix from modal electrical variables to natural electrical variables;
• means for proportioning a termination circuit having an impedance matrix approximating the characteristic impedance matrix;
• means for proportioning one of the transmitting circuits which combines the m input signals, without using a transformer for this purpose, according to linear combinations defined by the transition matrix from modal electrical variables to natural electrical variables, so as to obtain at the output of said one of the transmitting circuits, output being connected to the n transmission conductors, the generation of modal electrical variables, each being proportional to a single signal among the input signals;
• and
• means for proportioning one of the receiving circuits, the input of which is connected to the n transmission conductors, which combines, without using a transformer for this purpose, the signals present on the transmission conductors according to linear combinations defined by the inverse of the transition matrix from modal electrical variables to natural electrical variables, 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 output signal being proportional to a single modal electrical variable among the modal electrical variables.

A device for transmission providing, in a known frequency band, m transmission channels each corresponding to a signal to be sent from the input of at least one transmitting circuit to the 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, n being an integer greater than or equal to m, the interconnection being proportioned in such a way that the interconnection may, taking into account the lumped impedances seen by the interconnection and caused by the circuits connected to the interconnection elsewhere than at the ends of the interconnection, be modeled as a multiconductor transmission line having uniform electrical characteristics over its length for the known frequency band;
• one or two termination circuits, each arranged at one end of the interconnection and each having, in the known frequency band, an impedance matrix approximating the characteristic impedance matrix of the multiconductor transmission line, the termination circuits, if there are several termination circuits, being each arranged at a different end of the interconnection;
• at least one of the transmitting circuits for combining the m input signals, without using a transformer for this purpose, according to linear combinations defined by a transition matrix from modal electrical variables to natural electrical variables, in order to obtain at the output of said one of the transmitting circuits, output being connected to the n transmission conductors, the generation of modal electrical variables, each being proportional to a single signal among the input signals;
• and
• at least one of the receiving circuits, the input of which is connected to the n transmission conductors for combining, without using a transformer for this purpose, the signals present on the transmission conductors, according to linear combinations defined by the inverse of the transition matrix from modal electrical variables to natural electrical variables, 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 output signal being proportional to a single modal electrical variable among the modal electrical variables.