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