GENERAL DESCRIPTION

The AD9776A/AD9778A/AD9779A are dual, 12-/14-/16-bit, high dynamic range digital-to-analog converters (DACs) that provide a sample rate of 1 GSPS, permitting a multicarrier generation up to the Nyquist frequency. They include features optimized for direct conversion transmission applications, including complex digital modulation and gain and offset compensation. The DAC outputs are optimized to interface seamlessly with analog quadrature modulators such as the ADL537x FMOD series from Analog Devices, Inc. A 3-wire interface provides for programming/readback of many internal parameters. Full-scale output current can be programmed over a range of 10 mA to 30 mA. The devices are manufactured on an advanced 0.18 μm CMOS process and operate on 1.8 V and 3.3 V supplies for a total power consumption of 1.0 W. They are enclosed in a 100-lead thin quad flat package (TQFP).

FEATURES

Low power: 1.0 W @ 1 GSPS, 600 mW @ 500 MSPS,

full operating conditions

Single carrier W-CDMA ACLR = 80 dBc @ 80 MHz IF

Analog output: adjustable 8.7 mA to 31.7 mA,

RL = 25 Ω to 50 Ω

Novel 2×, 4×, and 8× interpolator/coarse complex modulator

allows carrier placement anywhere in DAC bandwidth

Auxiliary DACs allow control of external VGA and offset control

Multiple chip synchronization interface

High performance, low noise PLL clock multiplier

Digital inverse sinc filter

100-lead, exposed paddle TQFP

APPLICATIONS

Wireless infrastructure

W-CDMA, CDMA2000, TD-SCDMA, WiMax, GSM, LTE

Digital high or low IF synthesis

Internal digital upconversion capability

Transmit diversity

Wideband communications: LMDS/MMDS, point-to-point