A cost-effective thermal compensation technique for CMOS digital integrated circuits (ICs) is proposed. The technique features a temperature-adaptive dc-dc converter serving as both temperature detector and variable power supply. The converter adopts a delay-line-based analog-to-digital converter to translate the temperature information into digital signals. By adjusting the output voltage, the dc-dc converter can help stabilize the ICs' operating frequency. The system was fabricated with a standard 1.5-mum digital CMOS process. With a supply of 3.3 V, the converter is capable of providing a variable supply voltage of 1.1-2.0 V with a maximum power efficiency of 92.1%. With this compensation technique, the temperature sensitivity of ICs is reduced from 4046 to 74 ppm/degC within a temperature range of 0-110degC