A Time-Domain SAR Smart Temperature Sensor With Curvature Compensation and a 3[sigma] Inaccuracy of -0.4°C ~ +0.6°C Over a 0°C to 90°C Range

• Published in: IEEE journal of solid-state circuits 2010-03, Vol.45 (3), p.600
• Main Authors: Chen, Poki, Chen, Chun-Chi, Peng, Yu-Han, Wang, Kai-Ming, Wang, Yu-Shin
• Format: Article
• Language: English
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2010.2040658

This paper describes a time-domain temperature sensor based on a successive approximation algorithm. Without using any bipolar transistor, a temperature sensor composed of a temperature-dependent delay line (TDDL) is utilized to generate a delay proportional to the measured temperature. A binary-weighted adjustable reference delay line (ARDL) is adopted with an effective delay varied by a SAR control logic to approximate the TDDL delay for output coding. For linearity enhancement, a curvature compensation between both delay lines is invented to achieve the best ever accuracy among inverter-delay-based smart temperature sensors. With two-point calibration, a [Formula Omitted]0.4[Formula Omitted][Formula Omitted][Formula Omitted]0.6[Formula Omitted] inaccuracy (3[Formula Omitted]) over a 0[Formula Omitted] temperature operation range has been measured for 23 test chips. With 10 output bits, the proposed sensor achieves a resolution better than 0.1[Formula Omitted] and a chip area of 0.6 [Formula Omitted] in a TSMC 0.35-[Formula Omitted] standard digital CMOS process. The sensor's average current consumption is 11.1 [Formula Omitted] at a conversion rate of 2[Formula Omitted]samples/s.