REV. A

Information furnished by Analog Devices is believed to be accurate and

reliable. However, no responsibility is assumed by Analog Devices for its

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

otherwise under any patent or patent rights of Analog Devices.

a

CMOS

Complete DDS

AD9831

© Analog Devices, Inc., 1996

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

Tel: 617/329-4700

Fax: 617/326-8703

FEATURES

3 V/5 V Power Supply

25 MHz Speed

On-Chip SINE Look-Up Table

On-Chip 10-Bit DAC

Parallel Loading

Powerdown Option

72 dB SFDR

125 mW (5 V) Power Consumption

40 mW (3 V) Power Consumption

48-Pin TQFP

APPLICATIONS

DDS Tuning

Digital Demodulation

GENERAL DESCRIPTION

This DDS device is a numerically controlled oscillator employ-

ing a phase accumulator, a sine look-up table and a 10-bit D/A

converter integrated on a single CMOS chip. Modulation

capabilities are provided for phase modulation and frequency

modulation.

Clock rates up to 25 MHz are supported. Frequency accuracy

can be controlled to one part in 4 billion. Modulation is effected

by loading registers through the parallel microprocessor

interface.

A powerdown pin allows external control of a powerdown

mode. The part is available in a 48-pin TQFP package.

FUNCTIONAL BLOCK DIAGRAM

RESET

SLEEP

IOUT

COMP

REFIN

FS ADJUST

REFOUT

AGND

AVDD

DGND

DVDD

MCLK

D0

FSELECT

D15

WR

A0

A1

A2

PSEL0

PSEL1

12

Σ

AD9831

ON-BOARD

REFERENCE

10-BIT DAC

PHASE0 REG

PHASE1 REG

PHASE2 REG

PHASE3 REG

TRANSFER CONTROL

MPU INTERFACE

FULL-SCALE

CONTROL

SIN

ROM

PHASE

ACCUMULATOR

(32-BIT)

MUX

FREQ0 REG

FREQ1 REG

MUX

PARALLEL REGISTER