Low Power, High Speed

CCD Buffer Amplifier

ADA4800

Rev. A

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FEATURES

Integrated active load and gain of 1 buffer

Very low buffer power consumption

As low as 20 mW on chip

Power save feature to reduce active load current by GPO

control

High buffer speed

400 MHz, −3 dB bandwidth

415 V/μs slew rate

Fast settling time to 1%, 2 V step: 5 ns

Adjustable buffer bandwidth

Push-pull output stage

Adjustable active load current

Small package: 1.6 mm × 1.6 mm × 0.55 mm

APPLICATIONS

CCD image sensor output buffer

Digital still cameras

Camcorders

FUNCTIONAL BLOCK DIAGRAM

6

ISF

1

IN

5

VCC

2

VEE

4

IDRV

3

OUT

ADA4800

+1

Figure 1.

GENERAL DESCRIPTION

The ADA4800 is voltage buffer integrated with an active load.

The buffer is a low power, high speed, low noise, high slew rate,

fast settling, fixed gain of 1 monolithic amplifier for charge-

coupled device (CCD) applications. For CCD applications, the

sensor outputs and the buffer can drive the AFE load. The active

current load can also be switched off, to use the ADA4800 as just

a unity gain buffer. The buffer consumes only 20 mW of static

power. In applications where power savings is critical, the

ADA4800 features a power save mode (see the Power Save

Mode section), which further reduces the total current

consumption. The bandwidth of the ADA4800 buffer is also

fully adjustable through the IDRV pin.

The buffer of the ADA4800 employs a push-pull output stage

architecture, providing drive current and maximum slew

capability for both rising and falling signal transitions. At a

5 mA quiescent current setting, it provides 400 MHz, −3 dB

bandwidth, which makes this buffer well suited for CCD

sensors from machine vision to digital still camera applications.

The ADA4800 is ideal for driving the input of the Analog

Devices, Inc., 12-bit and 14-bit high resolution analog

front ends (AFE) such as the AD9928, AD9990, AD9920A,

AD9923A, and AD997x family.

The versatility of the ADA4800 allows for seamless interfacing

with many CCD sensors from various manufacturers.

The ADA4800 is designed to operate at supply voltages as low

as 4 V and up to 17 V. It is available in a 1.6 mm × 1.6 mm ×

0.55 mm, 6-lead LFCSP package and is rated to operate over the

6

ISF

1

IN

5

VCC

2

VEE

4

IDRV

3

OUT

ADA4800

10k

Ω

3V

7.5V

249k

Ω

15V

0.1µF

+

10µF

49.9

Ω

7.5V

1k

Ω

10

Ω

22pF

+1

Figure 2. Typical Test Circuit