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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.

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

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