An ultra low noise readout integrated circuit for uncooled microbolometers

A low noise readout architecture for uncooled microbolometer focal plane arrays is described. The on-chip readout circuit contains an integration circuit in which the bolometer current is directed injected into a capacitor, and exhibits extremely low noise with no decrease in signal by using an ultra low noise capacitive transimpedance amplifier (CTIA). The simple configuration of the integration circuit makes it possible to operate more circuits in parallel, and increases the integration time and number of pixels. A 40 × 30 uncooled microbolometer focal plane array based on the low noise ROIC was implemented on silicon using a 0.5 μm CMOS technology. The total output noise voltage is 260 μV RMS. A noise at this level is so low that can loosen required TCR in the bolometer material. Experimental values of voltage responsivities of 3.98 × 10⁵ V/W on average at 1 Hz modulation frequency have been achieved.