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 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.