A Compact Resistor-Based CMOS Temperature Sensor With an Inaccuracy of 0.12 °C (3σ) and a Resolution FoM of 0.43 pJ . K2 in 65-nm CMOS

This paper presents a compact resistor-based CMOS temperature sensor intended for dense thermal monitoring. It is based on an RC poly-phase filter (PPF), whose temperature-dependent phase shift is read out by a frequency-locked loop (FLL). The PPF's phase shift is determined by a zero-crossing (ZC) detector, allowing the rest of the FLL to be realized in an area-efficient manner. Implemented in a 65-nm CMOS technology, the sensor occupies only 7000 mu m(2). It can operate from supply voltages as low as 0.85 V and consumes 68 mu W. A sensor based on a PPF made from silicided p-poly resistors and metal-insulator-metal (MIM) capacitors achieves an inaccuracy of +/- 0.12 degrees C (3 sigma) from -40 degrees C to 85 degrees C and a resolution of 2.5 mK (rms) in a 1-ms conversion time. This corresponds to a resolution figure-of-merit (FoM) of 0.43 pJ.K-2.