Digitally controlled wide range pulse width modulator for on-chip power supplies

A digitally controlled current starved pulse width modulator is described in this paper. The current from the power grid to the ring oscillator is controlled by a header circuit. By changing the header current, the pulse width of the switching signal generated at the output of the ring oscillator is dynamically controlled, permitting the duty cycle to vary between 50% and 90%. A duty cycle to voltage converter is used to ensure the accuracy of the system under process, voltage, and temperature (PVT) variations. The accuracy and performance of the proposed digitally controlled pulse width modulator is evaluated with 22 nm CMOS predictive technology models under PVT variations. The proposed pulse width modulator is appropriate for dynamic voltage scaling systems due to the small on-chip area and high accuracy under process, voltage, and temperature variations. Although the frequency of the switching signal is affected by changes in the duty cycle, the frequency variations are typically negligible.