| 摘要 |
A column amplifier architecture having automatic gain selection for CMOS image sensors, which reduces the effect of analog noise, while maintaining a system's dynamic range. A comparator compares an amplified column buffer output signal to a reference voltage. The output of the comparator controls the gain of the amplifier based on the result of the comparison. Initially, a high column buffer gain is selected. For small signals, the output of the column buffer stays below the reference voltage and the output signal stays within the system's dynamic range. For larger signals, the column buffer output will exceed the reference voltage (and also the system's dynamic range) and therefore the comparator output switches states, which selects the low-gain setting. Multiple gain levels may be implemented, if desired.
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