AD9959

Preliminary Technical Data

Rev. PrB | Page 6 of 9

PRODUCT OVERVIEW

The AD9959 consists of four independently programmable

DDS channels. The AD9959 features independent frequency,

phase, and amplitude control of each channel; this allows for the

correction of imbalances due to analog processing such as

filtering, amplification, or PCB layout related mismatches. The

AD9959 supports frequency sweeping for radar and

instrumentation applications. Since all four channels share a

common system clock, they are inherently synchronized. If

more than four channels are required, synchronizing multiple

AD9959s is a simple task.

The AD9959 uses advanced DDS technology which provides

low power dissipation with high performance. The device

incorporates four integrated high speed 10-bit DACs with

excellent wideband and narrowband SFDR. Each DDS has a 32-

bit frequency tuning word, 14-bits of phase offset, and a 10-bit

output scale multiplier.

Each DAC has it own programmable reference to enable a

different full scale current for each channel.

Each DDS acts as a high resolution frequency divider with the REF_

CLK as the input and the DAC providing the output. The REF_CLK

input source is common to all DDS channels, and can be driven

directly, or used in combination with an integrated REF_CLK

multiplier (using a PLL) up to a maximum of 500 MSPS. The REF_

CLK multiplication factor is programmable from 4 to 20, in integer

steps. The REF_CLK input features an oscillator which supports either

a crystal as a source, or may be bypassed. The crystal frequency must

be between 20MHz and 30MHz. The crystal can be used with or

without the REF_CLK multiplier.

The DAC outputs are supply referenced and must be terminated into

AVDD by a resistor, or an AVDD center-tapped transformer.

The AD9959 comes in a space-saving 56-lead LFCSP package. The

DDS core (AVDD and DVDD pins) must be powered by a 1.8V supply.

The digital I/O interface (SPI) operates at 3.3V and requires that the

pin labeled “DVDD_I/O” (pin 49) be connected to 3.3V.

The AD9959 operates over the industrial temperature range of -40C to

+85