GENERAL DESCRIPTION

The AD9775 is the 14-bit member of the AD977x pin compatible, high performance, programmable 2×/4×/8× interpolating TxDAC+ family. The AD977x family features a serial port interface (SPI) that provides a high level of programmability, thus allowing for enhanced system-level options. These options include selectable 2×/4×/8× interpolation filters; fS/2, fS/4, or fS/8 digital quadrature modulation with image rejection; a direct IF mode; programmable channel gain and offset control; programmable internal clock divider; straight binary or twos complement data

interface; and a single-port or dual-port data interface. The selectable 2×/4×/8× interpolation filters simplify the requirements of the reconstruction filters while simultaneously enhancing the pass-band noise/distortion performance of TxDAC+ devices. The independent channel gain and offset adjust registers allow the user to calibrate LO feedthrough and sideband suppression errors associated with analog quadrature modulators. The 6 dB of gain adjustment range can also be used to control the output power level of each DAC.

FEATURES

14-bit resolution, 160 MSPS/400 MSPS input/output data rate

Selectable 2×/4×/8× interpolating filter

Programmable channel gain and offset adjustment

fS/4, fS/8 digital quadrature modulation capability

Direct IF transmission mode for 70 MHz + IFs

Enables image rejection architecture

Fully compatible SPI® port

Excellent ac performance

SFDR: −71 dBc @ 2 MHz to 35 MHz

W-CDMA ACPR: −71 dB @ IF = 19.2 MHz

Internal PLL clock multiplier

Selectable internal clock divider

Versatile clock input

Differential/single-ended sine wave or TTL/CMOS/LVPECL compatible

Versatile input data interface

Twos complement/straight binary data coding

Dual-port or single-port interleaved input data

Single 3.3 V supply operation

Power dissipation: 1.2 W @ 3.3 V typical

On-chip, 1.2 V reference

80-lead, thin quad flat package, exposed pad (TQFP_EP)

APPLICATIONS

Communications

Analog quadrature modulation architecture

3G, multicarrier GSM, TDMA, CDMA systems

Broadband wireless, point-to-point microwave radios

Instrumentation/ATE