A 28nm CMOS ultra-compact thermal sensor in current-mode technique

Abstract

This paper describes an innovative architecture for temperature sensors, which achieves excellent linearity at minimum complexity. Fabricated in 28nm, the circuit occupies only 0.0038mm2 and draws 16μA from 1.8V, capable also for lower supplies. The 8-bit smart sensor operates from -20 to 130°C and utilizes the benefits of parasitic NPN transistor. Current-mode technique is adopted in a new way, which simplifies digital output and makes common error correction dispensable. Excellent PSRR and a raw accuracy of 1.8°C (3σ) is obtained without calibration, due to the inherent robustness against MOS mismatch. Precision can be increased to ~ +/-0.8°C by convenient single point soft-trimming. (smart thermal sensor, current-mode, NPN bipolar, CMOS)