Per-Pixel Floating-Point ADCs with Electronic Shutters for a High Dynamic Range, High Frame Rate Infrared Focal Plane Array

A per-pixel floating-point, dual-slope A/D converter (ADC) array for a 16 times 16 long wavelength infrared detector array has been integrated in a 0.18-mum CMOS technology. To achieve a high dynamic range and high frame rate simultaneously, an electronic shutter is combined with an ADC for each pixel. A unique method of comparator offset cancellation, employing an integration capacitor with digital calibration, improves the uniformity of the array. The experimental prototype achieves a 19-bit dynamic range and 8-bit resolution at 3 kfps, with a power consumption of only 7 muW/pixel. Each per-pixel ADC occupies 4000 mum2 and is well-suited to 3-dimensional integration