US Patent 7359694 - CNT RF mixer

http://www.freepatentsonline.com/7359694.html

This patent from Northrop Grumman Corporation teaches forming pn diodes using carbon nanotubes and arranging these nanotube diodes in a quad configuration commonly seen in full wave rectifier circuitry. The benefit of the circuit is taught to be found in high frequency (>terahertz) mixers. Claim 1 reads:

1. A diode quad comprising:

a substrate;

first and second electrodes formed on the surface of said substrate and separated by a first gap;

fourth and third electrodes formed on the surface of the substrate and separated by a second gap, a portion of said fourth and said third electrodes being formed in said first gap;

a first p-n junction carbon nanotube diode connecting said first electrode with said third electrode;

a second p-n junction carbon nanotube diode connecting said first electrode with said fourth electrode;

a third p-n junction carbon nanotube diode connecting said second electrode with said third electrode; and

a fourth p-n junction carbon nanotube diode connecting said second electrode with said fourth electrode.