Patent ID: 6060952
Filing Date: 2000-05-09
Classification: H03F

Abstract:
An amplifier circuit for an infrared sensor for amplifying outputs from a plurality of passive infrared detectors in a single system of an amplifier circuit by cyclically switching, said amplifier circuit including a two-stage amplifier circuit comprising:a primary stage amplifier;a second stage amplifier;a plurality of series circuits provided between said primary stage amplifier and said second stage amplifier, there being the same number of said series circuits as the number of said passive infrared detectors; anda bias voltage generating circuit for providing a predetermined bias voltage to said primary stage amplifier and said second stage amplifier,wherein said series are connected in parallel and each said series circuit comprises at least one capacitor to determine a low frequency cut off and at least one switch to be switched over in synchronization with cyclic switching of outputs from said passive infrared detectors.