This letter describes an NPN-based temperature sensor that achieves a 1-point trimmed inaccuracy of ±0.15 °C (3σ) from -15 to 85 °C while dissipating only 210 nW. It uses a dual-mode frontend to roughly halve the power consumption of conventional frontends. First, two NPNs are used to generate a well-defined PTAT bias current, then this current is sampled and applied to the same NPNs to generate well-defined PTAT and CTAT voltages. These voltages are then applied to a low-power tracking ΔΣ modulator-based ADC, which employs a digital filter to efficiently generate a multibit representation of temperature. A prototype fabricated in a 180-nm BCD process achieves 15-mK resolution in a 50 ms conversion time, which translates into a state-of-the-art resolution FoM of 2.3 pJK2.

This paper presents a 210nW BJT-based temperature sensor that achieves an inaccuracy of ±0.15°C (3s) from -15°C to 85°C. A dual-mode front-end (FE), which combines a bias circuit and a BJT core, halves the power needed to generate well-defined CTAT (VBE) and PTAT (?VBE) voltages. The use of a tracking ?S ADC reduces FE signal swing and further reduces system power consumption. In a 180-nm BCD process, the prototype achieves a 15mK resolution in 50ms conversion time, translating into a state-of-the-art FoM of 2.3pJK2.