Use of negative permeability metamaterials to improve signal impedance

Signal integrity is an important issue in signal interface circuits. Impedance mismatches between different discontinuities can cause significant signal distortion. However, sometimes this cannot be easily avoided due to the tendency of package interconnects to have higher impedance than other parts of the system. To mitigate this problem it would be advantageous to design the dielectric to achieve desired signal impedance without changing materials from the current inexpensive material set. A means to achieve this is by using so called "metamaterials". Metamaterials can be designed to achieve desired dielectric properties even to the point of non-positive values of permittivity or permeability for a specific frequency range. By adjusting the dielectric properties in this way, better interconnect impedance can be achieved