An apparatus for use with automatic testing equipment for testing infrared sensors on integrated circuits is provided. The apparatus includes an infrared source, a heat mass, and an electronic frequency modulator. The infrared source is modulated according to a predetermined test frequency such that the infrared source emits an infrared test signal representative of a test temperature and corresponding to the temperature of the heat mass and the predetermined test frequency. A signal processor, electrically coupled to an integrated circuit having an infrared sensor, receives a sensed signal from the infrared sensor in response to the infrared test signal and uses the sensed signal according to the predetermined test frequency to determine a measured temperature.