A 0.45-V MOSFETs-Based Temperature Sensor Front-End in 90 nm CMOS With a Noncalibrated $\pm \hbox{3.5} \ ^{\circ}\hbox{C} \ \hbox{3}\sigma$ Relative Inaccuracy From $-\hbox{55} \ ^{\circ}\hbox{C}$ to 105 $^{\circ}\hbox{C}$

This brief presents a low-voltage subthreshold MOSFETs-based scattered relative temperature sensor that uses a simple regulated current mirror structure. NMOSFETs in the subthreshold region instead of bipolar junction transistors are used as sensing devices for low voltage purpose. Dynamic element matching is implemented to minimize the errors induced by device mismatches. The 3 × 3 sensor nodes with small size are remotely distributed across the chip, whereas the other parts are centralized and shared. Experimental results show that the minimum analog supply voltage can be 0.45 V from -55°C to 105°C in a 90-nm process implementation. The measured 3σ relative inaccuracy was less than ±3.5°C without any calibration. Furthermore, the multilocation thermal monitoring function has been experimentally demonstrated, and a 2.2°C/mm on-chip temperature gradient was detected. Compared with our previous design, superior line sensitivity and comparable relative accuracy are realized with simpler circuit implementation.