Taiwanese design house Richtek has filed a patent infringement complaint with the US International Trade Commission (ITC) against uPI Semiconductor, AMD, Sapphire Technology, Diamond Multimedia and XFX.

The outfit claims that the graphics chip makers have been nicking their technology related to Pulse Width Modulation. Richtek said that technology involved in the graphics chip company's portfolios violate its patents No. 7315190, 6414470 and 7132717.

The first patent is for a PWM (Pulse Width Modulation) circuit, which can get an external programming signal without any extra pin. The second is a method for current balance in a multi-phase DC-to-DC converter to produce a respective PWM signal to regulate the corresponding channel current. The third is for a power metal oxide semiconductor transistor layout comprising: a gate electrode with a lattice pattern on a substrate having a first area and a second area. (You lost me at 'the'. sub.ed.)

All heavy technology and probably not something that is going to grab the headlines.