TC271

1080

× 580-PIXEL CCD IMAGE SENSOR

SOCS039A – JANUARY 1994 – REVISED JUNE 1996

4

POST OFFICE BOX 655303

Terminal Functions

TERMINAL

I/O

DESCRIPTION

NAME

NO.

I/O

DESCRIPTION

ABG†

2

I

Antiblooming gate

ABG†

20

I

Antiblooming gate

ADB

5

I

Supply voltage for amplifier-drain bias

AMP GND

9

Amplifier ground

CDB

10

I

Supply voltage for clearing-drain bias

IAG†

3

I

Image-area gate

IAG†

19

I

Image-area gate

OUT1

8

O

Output signal 1

OUT2

7

O

Output signal 2

OUT3

6

O

Output signal 3

SAG1

4

I

Storage-area gate

SAG2

17

I

Storage-area gate

SRG1

14

I

Serial-register gate 1

SRG2

15

I

Serial-register gate 2

SRG3

16

I

Serial-register gate 3

SUB†

1

Substrate and clock return

SUB†

11

Substrate and clock return

SUB†

12

Substrate and clock return

SUB†

22

Substrate and clock return

TDB

21

I

Supply voltage for top-drain bias

TMG

18

I

Transfer-multiplex gate

TRG

13

I

Transfer gate

† All pins of the same name should be connected together externally (i.e., pin 2 to pin 20,

pin 3 to pin 19, etc.).

detailed description

The TC271 consists of five basic functional blocks: (1) the image-sensing area, (2) the multiplexer block, (3)

the image-storage area with dual-field memories, (4) the serial-register and transfer gates, and (5) the low-noise

signal-processing amplifier block with charge-detection nodes. The location of each of these blocks is identified

in the functional block diagram.

image-sensing area

Figure 4 and Figure 5 show cross sections with potential-well diagrams and top views of image-sensing

elements. As light enters the silicon in the image-sensing area, free electrons are generated and collected in

the potential wells of the sensing elements. During this time, blooming protection is activated by applying a burst

of pulses to the antiblooming-gate inputs every horizontal-blanking interval. This prevents blooming caused by

the spilling of charge from overexposed elements into neighboring elements. Thirty-four full columns and one

half-column of elements at the right edge of the image-sensing area are shielded from incident light; these

elements provide the dark reference used in subsequent video-processing circuits to restore the video-black

level. There are also one full column and one half-column of light-shielded elements at the left edge of the

image-sensing area and four lines of light-shielded elements at the bottom of the image area immediately above

the multiplexer. The latter prevent charge leakage from the image area into the multiplexer.