A BJT-based temperature-to-digital converter with ±60mK (3σ) inaccuracy from −70°C to 125°C in 160nm CMOS

Abstract

This paper presents the most accurate BJT-based CMOS temperature-to-digital converter (TDC) ever reported, with an inaccuracy of ±60mK (3σ) from -70°C to 125°C. This is 2× better than the state-of-the-art, despite being implemented in a process (160nm) that only offers low-β_F (<;5) PNPs. It is also the most energy-efficient ever reported, with a resolution FOM of 7.3pJ°C². This level of performance is achieved by an improved β_F-compensation scheme, the use of dynamic error correction techniques to suppress non-BJT related errors and the use of an energy-efficient zoom-ADC based on current-reuse OTAs. These techniques also result in very low power-supply sensitivity (12mK/V), thus maintaining TDC accuracy for supply voltages ranging from 1.5V to 2V.