Compact PNP BJT-Based Temperature Sensor and Sub-1-V Bandgap Reference for SoC Applications in 4-nm FinFET

Abstract

This article presents a dual-function circuit of a temperature sensor and a sub-1-V bandgap reference (BGR) implemented in the 4-nm FinFET CMOS process. The design, based on subthreshold MOS transistors and parasitic PNP bipolar junction transistor (BJT) devices, offers distinct advantages over existing PNP BJT-based sensors and sub-1-V BGRs. As a temperature sensor, it achieves the fastest conversion time of $7~{\mu }$ s, while consuming a power of only $68.5~{\mu }$ W, which results in the lowest energy consumption rate of 0.5 nJ per conversion. In addition, the sensor demonstrates a resolution of $0.46~{^{\circ }}$ C and a resolution figure-of-merit (FOM) of 0.106 nJ $\cdot $ K2. It also functions as a low-cost, high-accuracy BGR capable of sub-1-V operation, producing a stable output of 450 mV within a compact 0.0061 mm2 footprint, and featuring an accuracy of $\pm 1.1\% (\pm 3\sigma)$ along with an average temperature coefficient (TC) of 33 ppm/°C. Moreover, by supporting both BGR and sensing modes, the design significantly reduces costs by incorporating dual functionalities within a single architecture.