Low Cost CMOS On-Chip and Remote Temperature Sensors

Ming-Chan WENG  Jiin-Chuan WU  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E84-C   No.4   pp.451-459
Publication Date: 2001/04/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Integrated Electronics
Keyword: 
temperature sensor,  bandgap reference,  A/D converter,  CMOS,  

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Summary: 
This paper describes the design and results of low cost integrated CMOS local and remote temperature sensors with digital outputs. No trimming is needed to obtain good temperature linearity, so that only one-temperature calibration is needed which greatly reduces testing cost. The base-emitter voltage of the parasitic substrate bipolar transistor is used to measure the local temperature. A diode-connected external bipolar transistor is used to measure the remote temperature. Chopper techniques were used to cancel the offset voltage of the op-amp, so that a precise bandgap voltage can be obtained without resistance trimming. A first order ΣΔ ADC was used to produce the digital output. The local and remote temperature sensors were realized in a 0.6 µm single-poly triple-metal CMOS technology with active area of 0.6 mm2 and 0.65 mm2, respectively. After calibration, the error is 1 for the local temperature sensor over the temperature range of -20 to 130, and 2 for the remote temperature sensor over the range of 0 to 120. The supply currents of the local and remote temperature sensors are 3.5 µA and 38 µA at 8 samples/s, respectively.