An enhanced pulse width modulator with adaptive duty cycle and frequency control

A digitally controlled pulse width modulator (PWM), targeting on-chip power management applications is proposed in this paper. A current starved ring oscillator, with digitally controlled current source based headers and footers, is used to provide a versatile duty cycle and an accurate frequency control. The proposed circuit achieves i) a controlled duty cycle that can vary between 20% and 90% and ii) a compensation circuit that guarantees a constant duty cycle under process, voltage, and temperature (PVT) variations. A fast response time of 5 ns - 20 ns with a fine duty cycle granularity has been achieved through the proposed control techniques. The circuit operates at a frequency range of 500 MHz - 1.66 GHz and is implemented with a 22 nm CMOS predictive technology model.