TC255P

336-

× 244-PIXEL CCD IMAGE SENSOR

SOCS057 – JUNE 1996

2-6

POST OFFICE BOX 655303

charge-detection node and output amplifier

The buffer amplifier converts charge into a video signal. Figure 4 shows the circuit diagram of the

charge-detection node and output amplifier. As charge is transferred into the detection node, the potential of

this node changes in proportion to the amount of signal received. This change is sensed by an MOS transistor

and, after proper buffering, the signal is supplied to the output terminal of the image sensor. After the potential

change is sensed, the node is reset to a reference voltage supplied by an on-chip reference generator. The reset

is accomplished by a reset gate that is connected internally to the serial register. The detection node and buffer

amplifier are located a short distance from the edge of the storage area; therefore, two dummy cells are used

to span this distance.

Reference

Generator

Q0

Q1

Q2

Q3

Q5

Q6

VO

Q4

QR

SRG

Detection

Node

ADB

Figure 4. Buffer Amplifier and Charge-Detection Node