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 ADL537x 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 AD978x 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 paddle TQFP package
APPLICATIONS
Wireless infrastructure
WCDMA, CDMA2000, TD-SCDMA, WiMAX, GSM
Digital high or low IF synthesis
Transmit diversity
Wideband communications
LMDS/MMDS, point-to-point