FUNCTIONAL BLOCK DIAGRAM

REV. A

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use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

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a

Ultrahigh Speed IC

D/A Converter

AD9768

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

Fax: 617/326-8703

FEATURES

5 ns Settling Time

100 MSPS Update Rate

20 mA Output Current

ECL-Compatible

40 MHz Multiplying Mode

APPLICATIONS

Raster Scan & Vector Graphic Displays

High Speed Waveform Generation

Digital VCOs

Ultrafast Digital Attenuators

GENERAL DESCRIPTION

The Analog Devices AD9768SD D/A converter is a monolithic

current-output converter which can accept 8 bits of ECL-level

digital input voltages and convert them into analog signals at

update rates as high as 100 MSPS. In addition to its use as a

standard D/A converter, it can also be utilized as a two-quadrant

multiplying D/A at multiplying bandwidths as high as 40 MHz.

An inherently low glitch design is used, and the complementary

current outputs are suitable for driving transmission lines

directly. Nominal full-scale output is 20 mA, which corresponds

to a 1 volt drop across a 50

Ω load, or ±1 volt across 100 Ω

returned to +1 volt. The actual output current is determined by

–1.26 V) and an external

calculated with the equation:

both have low temperature coefficients. A complementary

AD9768JD/SD PIN CONNECTIONS

The reference voltage source is a modified bandgap type

and is nominally –1.26 volts. This reference supply requires

no external regulation. To reduce the possibility of noise

generation and/or instability, Pin 15 (REFERENCE OUT)

can be decoupled using a high-quality ceramic chip

capacitor. Stabilization of the internal loop amplifier is by a

single capacitor connected from Pin 17 (COMPENSATION)

to ground. The minimum value for this capacitor is 3900 pF,

although a 0.01

µF ceramic chip capacitor is recommended.

The incredible speed characteristics of the AD9768SD D/A

converter make it attractive for a wide range of high speed

applications. The ability of the unit to operate as a two-

quadrant multiplying D/A converter adds another dimen-

sion to its usefulness and makes the AD9768SD a truly

versatile device.

AD9768SE PIN CONNECTIONS