Fixed-pattern noise in photomatrices

Two MOS photomatrix configurations, voltage sampling and recharge sampling, have been compared with regard to sources of fixed-pattern noise. Voltage sampling provides a high-amplitude low-impedance photosignal, with FPN primarily due to threshold variation in the amplifying MOST at each element. Recharge sampling is used for large high-yield rapidly scanned arrays, with FPN caused mostly by variations in spurious capacitive breakthrough. Production peak-to-peak signal to FPN ratios are 20:1 for voltage sampling and 50:1 for recharge sampling.