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 0.0038mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 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)