A synthesizable pseudo fractional-N clock generator with improved duty cycle output

A proposed synthesizable pseudo fractional-N clock generator with improved duty cycle output is presented by the pseudo fractional-N frequency synthesizer unit for SoC chips and the dynamic frequency scaling applications. The different clock frequencies can be generated by following the design flowchart. It has been fabricated in a 0.13 μm CMOS technology and work with a supply voltage of 1.2 V. According to measured results, the frequency range of the proposed synthesizable pseudo fractional-N clock generator is from 12.5 MHz to 1 GHz and the peak-to-peak jitter is less than 5% of the output period. Duty cycle error rate of the output clock frequency is 1.5% and the measured power dissipation of the pseudo fractional-N frequency synthesizer unit is 146 μW at 304 MHz.

► Synthesizable pseudo fractional-N clock generator: generated by design flowchart.
► Wide output frequency range: the output frequency range is from 12.5 MHz to 1 GHz.
► 50% duty cycle output: achieved by the synthesizable pulse generator circuit.
► Low sensitivity to PVT: digital circuits are used to reduce sensitivity.