A SINGLE-CHIP CMOS SMOKE AND TEMPERATURE SENSOR FOR AN INTELLIGENT FIRE DETECTOR

A SINGLE-CHIP CMOS SMOKE AND TEMPERATURE 

SENSOR FOR AN INTELLIGENT FIRE DETECTOR  

Aug. 2009  

A single-chip CMOS  smoke  and temperature  sensor  for use  as  an intelligent fire  detector  is  proposed.  The  proposed  smoke  sensor  measures  smoke density based on the light-scattering method.  

The temperature sensor is integrated with the smoke sensor not only to sense heat from a fire but also to compensate for the temperature dependency of the smoke sensor.  

The   prototype   chip   includes   an   on-chip   photodiode   (PD),   pixel   circuit,  correlated  double  sampling  (CDS)  circuit,  and  analog-to-digital  converter  (ADC).  The  prototype  chip  was  fabricated  using  a  0.35-mu  m  CMOS  process and was placed inside the smoke detection chamber, while the thermistor for the temperature sensor is placed outside the chamber.  

The measurement results show plusmn 1% smoke detection accuracy over the range  4%  ~  25%  and  plusmn1degC  temperature-sensing  accuracy  over  the range  25degC  ~  95degC. The power consumption of  the prototype chip is  220 nW, excluding the infrared light-emitting diode (IR LED).