FEATURES

1 GSPS internal clock speed (up to 400 MHz analog output)

Integrated 1 GSPS 14-bit DAC

250 MHz I/Q data throughput rate

Phase noise ≤ −125 dBc/Hz (400 MHz carrier @ 1 kHz offset)

Excellent dynamic performance >80 dB narrow-band SFDR             FUNCTIONAL BLOCK DIAGRAM

8 programmable profiles for shift keying

SIN(x)/(x) correction (inverse sinc filter)                  

Reference clock multiplier

Internal oscillator for a single crystal operation

Software and hardware controlled power-down

Integrated RAM

Phase modulation capability

Multichip synchronization

Easy interface to Blackfin SPORT

Interpolation factors from 4× to 252×

Interpolation DAC mode

Gain control DAC

Internal divider allows references up to 2 GHz

1.8 V and 3.3 V power supplies

100-lead TQFP_EP package

APPLICATIONS

HFC data, telephony, and video modems

Wireless base station transmission

Broadband communications transmissions

Internet telephony

GENERAL DESCRIPTION

The AD9957 functions as a universal I/Q modulator and agile

upconverter for communications systems where cost, size, power

consumption, and dynamic performance are critical. The AD9957

integrates a high speed, direct digital synthesizer (DDS), a high

performance, high speed, 14-bit digital-to-analog converter (DAC),

clock multiplier circuitry, digital filters, and other DSP functions

onto a single chip. It provides for baseband upconversion for data

transmission in a wired or wireless communications system.

The AD9957 is the third offering in a family of quadrature

digital upconverters (QDUCs) that includes the AD9857 and

AD9856. It offers performance gains in operating speed, power

consumption, and spectral performance. Unlike its predecessors,

it supports a 16-bit serial input mode for I/Q baseband data.

The device can alternatively be programmed to operate either as

a single tone, sinusoidal source or as an interpolating DAC.

The reference clock input circuitry includes a crystal oscillator,

a high speed, divide-by-two input, and a low noise PLL for

multiplication of the reference clock frequency.

The user interface to the control functions includes a serial port

easily configured to interface to the SPORT of the Blackfin®

DSP and profile pins to enable fast and easy shift keying of any

signal parameter (phase, frequency, and amplitude).