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Type: 
Conference
Description: 
A complete gas-sensing system for portable ambient monitoring purpose, consisting of a sensor (with embedded heater and thermometer) and an integrated interface (with read-out channel and closed-loop temperature control circuit) is presented. The micromachined sol-gel tin-oxide sensor features a 450 nm thick silicon nitride/oxide membrane, an active area of 170 mum times 170 mum and a power consumption of 25 mW at 350degC in isothermal operation. The read-out circuit uses a current integration and resistance-to-frequency conversion, providing digital output. The sensor is biased with a constant voltage and its temperature is regulated by an on-off closed-loop control circuit, consisting of a thermometer conditioning network, an A/D converter and a digital control block that drives the on-chip output p-MOS power stage. The circuit can operate with different sensors to grant maximum flexibility. Chemical …
Publisher: 
IEEE
Publication date: 
26 Oct 2008
Authors: 

A Lombardi, L Bruno, M Grassi, P Malcovati, S Capone, L Francioso, P Siciliano, A Baschirotto

Biblio References: 
Pages: 596-599
Origin: 
SENSORS, 2008 IEEE