Programmable analog-to-digital converter for low-power DC-DC SMPS

An application-specific delay-line based windowed analog-to-digital converter (ADC) with programmable reference voltage, conversion time, and accuracy of voltage regulation, is introduced. The ADC can be fully implemented on a small silicon area and is suitable for implementation in various integrated digital controllers for high-frequency low-power switch-mode power supplies. The programmable characteristics are achieved through the utilization of the inherent averaging effect of the delay line and through the adjustments of delay cells' propagation times. The ADC is implemented in a standard 0.18 mu m CMOS technology, as a part of a high-frequency digital controller integrated circuit, and tested with a 1.5 MHz, 1 W buck dc-dc converter.