%0 Journal Article
%T A Linearization Time-Domain CMOS Smart Temperature Sensor Using a Curvature Compensation Oscillator
%A Chun-Chi Chen
%A Hao-Wen Chen
%J Sensors
%D 2013
%I MDPI AG
%R 10.3390/s130911439
%X This paper presents an area-efficient time-domain CMOS smart temperature sensor using a curvature compensation oscillator for linearity enhancement with a £¿40 to 120 ¡ãC temperature range operability. The inverter-based smart temperature sensors can substantially reduce the cost and circuit complexity of integrated temperature sensors. However, a large curvature exists on the temperature-to-time transfer curve of the inverter-based delay line and results in poor linearity of the sensor output. For cost reduction and error improvement, a temperature-to-pulse generator composed of a ring oscillator and a time amplifier was used to generate a thermal sensing pulse with a sufficient width proportional to the absolute temperature (PTAT). Then, a simple but effective on-chip curvature compensation oscillator is proposed to simultaneously count and compensate the PTAT pulse with curvature for linearization. With such a simple structure, the proposed sensor possesses an extremely small area of 0.07 mm 2 in a TSMC 0.35-mm CMOS 2P4M digital process. By using an oscillator-based scheme design, the proposed sensor achieves a fine resolution of 0.045 ¡ãC without significantly increasing the circuit area. With the curvature compensation, the inaccuracy of £¿1.2 to 0.2 ¡ãC is achieved in an operation range of £¿40 to 120 ¡ãC after two-point calibration for 14 packaged chips. The power consumption is measured as 23 mW at a sample rate of 10 samples/s.
%K curvature compensation
%K smart temperature sensor
%K oscillator
%K time-domain
%K delay line
%U http://www.mdpi.com/1424-8220/13/9/11439