Digitally programmable DC-DC voltage down converter

This paper describes a digitally programmable DC-DC voltage down converter (VDC) with a new structure of pulse width modulation (PWM) circuit. The PWM circuit is constructed by a cascaded digitally controlled oscillator (DCO) delay cells and provides two control words to select the operating frequency and duty cycle respectively. The VDC was implemented with a 0.6-/spl mu/m triple-metal CMOS process on 1000/spl times/1000 /spl mu/m/sup 2/ core size. The simulation results show that it can convert +5 V input voltage to +2/spl sim/+5 V output voltage in the 50 /spl mu/s settling time.