Dual-loop programmable and dividerless clock generator for ultra low power applications

摘要

A programmable clock generator is provided which is particularly suitable for low power applications. The programmable clock generator is comprised of: an oscillator circuit that generates an output signal whose frequency is set by a control signal, two feedback loops for controlling output frequency and a loop select that selects which feedback loop is operational at a given time. In operation, the frequency loop operates to coarsely adjust the frequency of the output signal; whereas, the phase loop operates to finely adjust the frequency of the output signal. The clock generator is preferably implemented by transistors operating in or near the subthreshold region.