Because SOC (system-on-a-chip) needs multiple clocks and mostly with 50% duty cycle in same chip. We use multiphase outputs of voltage-controlled oscillator (VCO) in a phase-locked loop (PLL) to generate the needed frequencies with 50% duty cycle. Further, we propose a design flowchart to solve the problem of pseudo fractional-N clock generator. The circuits are processed in a standard 0.13mum CMOS technology, and work with a supply voltage of 1.2V
Relation:
2006 IEEE International Symposium on Circuits and Systems (ISCAS 2006)