A Compact Resistor-Based CMOS Temperature Sensor With an Inaccuracy of 0.12 °C (3 <tex-math notation="LaTeX">σ </tex-math> ) and a Resolution FoM of 0.43 pJ <tex-math notation="LaTeX">· </tex-math> K <tex-math notation="LaTeX">² </tex-math> in 65-nm CMOS

This paper presents a compact resistor-based CMOS temperature sensor intended for dense thermal monitoring. It is based on an <tex-math notation="LaTeX">$RC$ </tex-math> 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 <tex-math notation="LaTeX">μ m~² </tex-math> . It can operate from supply voltages as low as 0.85 V and consumes 68 <tex-math notation="LaTeX">μ W </tex-math> . A sensor based on a PPF made from silicided p-poly resistors and metal–insulator–metal (MIM) capacitors achieves an inaccuracy of ±0.12 °C (3 <tex-math notation="LaTeX">σ </tex-math> ) from −40 °Cto 85 °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 <tex-math notation="LaTeX">· K~² </tex-math> .