A PIR sensor apparatus and method make use of a dc amplifier circuit. The dc amplifier circuit amplifies a dc-coupled sensor signal generated by a PIR sensor for analysis. For improved accuracy, the dc amplifier circuit is controlled to compensate for dc offset in the sensor signal. In this manner, the...http://www.google.com.au/patents/US6307200?utm_source=gb-gplus-sharePatent US6307200 - Passive infrared sensor apparatus and method with DC offset compensation
