An NPN-based temperature sensor with digital output transistors has been realized in a 65-nm CMOS process. It achieves a batch-calibrated inaccuracy of ±0.5 • C (3σ) and a trimmed inaccuracy of ±0.2 • C (3σ) over the temperature range from −70 • C to 125 • C. This performance is obtained by the use of NPN transistors as sensing elements, the use of dynamic techniques, i.e. correlated double sampling and dynamic element matching, and a single room-temperature trim. The sensor draws 8.3 µA from a 1.2-V supply and occupies an area of 0.1 mm 2. I. INTRODUCTION Temperature sensors are used in a wide range of commercial applications, ranging from the control of domestic appliances and industrial machinery to environmental monitoring. Fabrication costs can be reduced by implementing the sensors in standard digital CMOS processes. This enables the co-integration of the read-out electronics, so that a digital temperature reading can be directly provided to, for instance, a microcontroller. This work is funded by the European Commission in the Marie Curie project TRANDSSAT-2005-020461.