Crosstalk polarity reversal and cancellation through substrate material tuning

摘要

Transmission lines with a first dielectric material separating signal traces and a second dielectric material separating the signal traces from a ground plane. In embodiments, mutual capacitance is tuned relative to self-capacitance to reverse polarity of far end crosstalk between a victim and aggressor channel relative to that induced by other interconnect portions along the length of the channels, such as inductively coupled portions. In embodiments, a transmission line for a single-ended channel includes a material of a higher dielectric constant within the same routing plane as a microstrip or stripline conductor, and a material of a lower dielectric constant between the conductor and the ground plane(s). In embodiments, a transmission line for a differential pair includes a material of a lower dielectric constant within the same routing plane as a microstrip or stripline conductors, and a material of a higher dielectric constant between the conductors and the ground plane(s).

主权项

1. A method of fabricating transmission line circuitry for coupling a first and second input/output (I/O) channel of an integrated circuit (IC) disposed on a chip to an off-chip connection point, the method comprising:
forming a first conductive trace defining a routing path for the first I/O channel in a first metallization level disposed over a substrate; forming a second conductive trace defining a routing path for the second I/O channel in the first metallization level wherein the first I/O channel is separate and electrically isolated from the second I/O channel; forming a first dielectric material disposed between the first and second conductive traces; forming a ground plane in a second metallization level disposed over the substrate and above or below the first metallization level; and forming a second dielectric material disposed between the ground plane and the first and second conductive traces, wherein the second dielectric material has a different dielectric constant than that of the first dielectric material.