A 1.2 GHz programmable DLL-based frequency multiplier for wireless applications

A CMOS local oscillator using a programmable delayed-lock loop based frequency multiplier is present in this paper. The maximum measured output frequency is 1.2 GHz. The frequency of the output clock is 8/spl times/ to 10/spl times/ of an input reference clock between 100 to 150 MHz at simulation. No LC-tank is used in the proposed design such that the power dissipation as well as the active area is drastically reduced. The design is carried out by TSMC 1P5M 0.25 /spl mu/m CMOS process at 2.5 V power supply. The average lock time is optimally shortened by initializing the start-up voltage of the voltage-controlled delay tap line at the midway of the working range. Meanwhile, the power dissipation is 52.5 mW at 1.2 GHz output.