US Patent 7321270 Current-controlled CMOS ring oscillator circuit

A ring oscillator having an odd number of active elements connected in series, where the signal output of one active element is connected to the signal input of the next active element to form a closed ring of active elements. Each active element has a power supply input and a ground connection, a signal input and a signal output, an inverter sub-element having a pair of current mirrors, and a capacitor controlled bias sub-element.