This paper describes a precision temperature sensor based on dynamic threshold MOS (DTMOS) transistors. By using the DTMOS configuration, i.e. by connecting the body of a MOSFET to its gate, a near-ideal diode characteristic can be realized. The resulting device can then replace the substrate PNP used in most precision temperature sensors. After a two-temperature trim, the proposed sensor achieves an inaccuracy of ±0.1°C (3σ) over the military temperature range: -55°C to 125°C. This represents a 5x improvement in accuracy over previously reported MOSFET-based temperature sensors. The chip was implemented in a 0.16-μm standard CMOS process. At a conversion rate of 5Hz, it achieves a resolution of 33mK, while dissipating only 8.6 μW from a 1.8V supply.