GENERAL DESCRIPTION

The AD9785/AD9787/AD9788 are 12-bit, 14-bit, and 16-bit, high dynamic range TxDAC® devices, respectively, that provide a sample rate of 800 MSPS, permitting multicarrier generation up to the Nyquist frequency. Features are included for optimizing direct conversion transmit applications, including complex digital modulation, as well as gain, phase, and offset compensation. The DAC outputs are optimized to interface seamlessly with analog quadrature modulators, such as the ADL5375 family from Analog Devices, Inc. A serial peripheral interface (SPI) provides for programming and readback of many internal parameters. Full-scale output current can be programmed over a range of 10 mA to 30 mA. The AD9785/AD9787/AD9788 family is manufactured on a 0.18 μm CMOS process and operates from 1.8 V and 3.3 V supplies. It is enclosed in a 100-lead TQFP package.

FEATURES

Analog output: adjustable 8.7 mA to 31.7 mA,

RL = 25 Ω to 50 Ω

Low power, fine complex NCO allows carrier placement

anywhere in DAC bandwidth while adding <300 mW power

Auxiliary DACs allow I and Q gain matching and offset control

Includes programmable I and Q phase compensation

Internal digital upconversion capability

Multiple chip synchronization interface

High performance, low noise PLL clock multiplier

Digital inverse sinc filter

100-lead, exposed pad TQFP package

APPLICATIONS

Wireless infrastructure

W-CDMA, CDMA2000, TD-SCDMA, WiMAX, GSM

Digital high or low IF synthesis

Transmit diversity

Wideband communications

LMDS/MMDS, point-to-point