A low-noise Bi-CMOS linear image sensor with auto-focusing function

A bipolar imaging device consisting of a capacitor-loaded emitter follower circuit for a phototransistor has been implemented in a linear image sensor with two lines of 48-bit array for an autofocus camera system. The sensor, which has self-noise reduction and charge amplification capabilities, has demonstrated excellent performance, such as responsivity of 24 V/x-s, a wide dynamic range of 85.3 dB at a storage time of 10 ms and ambient temperature of 25 degrees C, a high S/N ratio of 27.6 dB at a faceplate light intensity of 1*10/sup -3/ lx, a storage time of 200 ms, an ambient temperature of 25 degrees C, and applicability in a range of light intensity from 1*10/sup -3/ to 1*10/sup 4/ lx. >