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