A CMOS uncooled heat-balancing infrared imager

In this paper, we report the fabrication, design, and testing of an uncoole d 8 x 8 infrared imager based on an active pixel heat balancing technique. The imager is fabricated using a commercial CMOS process plus a simple elec trochemical etch stop releasing step. The basic active pixel detector struc ture consists of a simple cascode CMOS amplifier in which the PMOS devices are built inside a thermally isolated floating n-well, The intrinsic coupli ng of the cascode currents with the self-heating of the well forms an elect rothermal feedback loop that tends to maintain the well temperature constan t. By employing the heat balance between incoming infrared radiation and th e PMOS device power dissipation, the responsivity of the detector is contro lled by the cascode biasing current, Measurements show responsivities betwe en 0.3-1.2 x 10(6) V/W when the infrared source is chopped at 20 Hz and a d etectivity D* = 3 x 10(7) cm root HzW(-1) at 30 Hz, Noise measurements sugg est that a D* of 10(8) cm root HzW(-1) is achievable in this design.