6

TH7899M

2201A–IMAGE–02/02

Output Amplifiers

The TH7899M sensor has four output amplifiers. These are located in each corner of

the device at the ends of the readout register. Charge packets are clocked to a pre-

charge capacitor (floating diffusion) whose potential varies linearly with the quantity of

charge in each packet. This potential is applied to the input gate of a two stage source

follower amplifier and the output signal is read. Then, the reset clock

ΦR removes the

charge from the floating diffusion via the reset drain VDR which imposes its reference

level.

Figure 5. On-chip Output Amplifier Structure

Multi-Pinned-Phase

(MPP) Mode

The TH7899M sensor operates in the MPP mode in order to substantially decrease dark

ogy, the MPP mode allows, while keeping all other performances unchanged, either to

increase exposure time, or to operate at higher temperature.

Dark current is due to thermal generation in the substrate of the CCD. The different gen-

eration sources are as follows:

•

surface states at the Si-SiO

•

generation and diffusion in the bulk

•

generation in the depleted zone

If the gates are biased with adequate negative biases, holes appear at the Si-SiO

face and fill in the interface states suppressing their dark current contribution. As a

result, only the minor bulk and depleted zone contributions remain.

Absolute Maximum Ratings*

Storage temperature..................................... -55°C to + 150°C

Operating temperature ................................... -40°C to + 85°C

Temperature cycling ...................................................15°C/mn

*NOTICE:

Stresses above those listed under ABSOLUTE

MAXIMUM RATINGS may cause permanent

device failure. Functionally at or above these lim-

its is not implied. Exposure to absolute maximum

ratings for extended periods may affect reliability.