An All-MOS Mixed Analog and Digital Circuit for Fire Detection

MOS technology allows to make on the same chip analog and digital functions provided the analog functions can be realized in standard technology. This is the case for an all-MOS P channel Al gate fire detector chip where temperature rise or smoke density rise (signal from an ionization chamber) provide an alarm signal. Maximum values of these parameters are also detected. Self testing on chip is made for indicating a malfunctioning of the chip.