There are many information about sensor, linear image sensor, and image sensor are described in this datasheet. This datasheet tells us discussion around internal gain, circuit, and sensor gain.
Inside the datasheet you can learn explanation about gain, driver circuit, and power supply. Here are selected from the datasheet:
The sensor is scanned in synchronization with this signal. Sensor scan start signal. The pulse interval of these start signals determines the sensor integration I time. Sensor gain setting. Low gain is selected at High level, and high gain at Low level. (External I gain setting is enabled with S2.) O Sensor end-of-scan signal. Negative logic O A/D conversion timing signal. The number of output pulses is equal to the number of pixels. Circuit ground I +5 V power supply line Circuit ground O Video output signal.
Additionally, this datasheet gives us discussion regarding signal, digital input, and cmos linear image.