Subthreshold-Hybrid Solutions for Thermal Sensor and Reference Circuits in Advanced CMOS

We present a family of hybrid structures, which combine subthreshold MOS operation with a single bipolar transistor. In contrast to typical BJT-based circuits, the PTAT voltage is generated from an asymmetric differential pair in weak inversion, and only the CTAT part depends on the parasitic PNP. A common feature is the signal generation and processing within a single feedback loop, which yields specifically simple solutions, with enhanced robustness towards supply and device variations. The bandgap reference, realized in 14/16nm FinFET, provides a 600mV output and > 60dB PSRR, at sub-1V power supply. We further present temperature sensors in 28nm CMOS and 14/16nm FinFET, which feature very low complexity and power. The first sensor includes a SAR ADC and achieves a precision of ± 3 °C after a 1-point trim under production conditions. The FinFE T sensor variant is a scaling-friendly solution, providing enhanced resolution with a duty-cycle modulated output.