TC253SPD

680×500 PIXEL CCD IMAGE SENSOR

SOCS062B – JANUARY 2001 – REVISED MAY 2002

5

POST OFFICE BOX 655303

Terminal Functions

TERMINAL

I/O

DESCRIPTION

NAME

NO.

I/O

DESCRIPTION

ADB

9

I

Supply voltage for amplifiers and clearing drain

CMG

6

I

Charge multiplication gate

IAG1

12

I

Image area gate 1

IAG2

2

I

Image area gate 2

NC

8

–

No connection

ODB

1

I

Supply voltage for antiblooming drain

VOUT

7

O

Output signal, multiplier channel

SAG1

11

I

Storage area gate 1

SAG2

3

I

Storage area gate 2

SRG1

4

I

Serial register gate 1

SRG2

5

I

Serial register gate 2

SUB

10

Chip substrate

detailed description

The TC253SPD sensor consists of four basic functional blocks: the image-sensing area, the image storage

area, the serial register, and the charge multiplier. The location of each of these blocks is identified in the

functional block diagram.

image-sensing and storage areas

Figure 1 and Figure 2 show cross sections with potential-well diagrams and top views of the pixels in the

image-sensing and storage areas. As light enters silicon in the image-sensing area, electrons are generated

and collected in potential wells of the pixels. Applying a suitable dc bias to the antiblooming drain provides

blooming protection. Electrons that exceed a specified level, determined by the ODB bias, are drained away

from the pixels. If it is necessary to remove all previously accumulated charge from the wells, a short positive

pulse must be applied to the drain. This marks the beginning of the new integration period. After the integration

cycle is completed, charge is quickly transferred into the memory where it waits for readout. The lines can be

read out from the memory in a sequential order to implement progressive scan, or two lines can be summed

together to implement the pseudo-interlace scan.

Twenty-two columns at the left edge of the image-sensing area are shielded from incident light. These pixels

provide the dark reference used in subsequent video-processing circuits to restore the video black level. An

additional four dark lines located between the image-sensing area and the image storage area were added for

isolation.