AD9776A Datasheet, PDF (1/56 Pages) Analog Devices – Dual, 12-/14-/16-Bit,1 GSPS Digital-to-Analog Converters

Dual, 12-/14-/16-Bit,1 GSPS
Digital-to-Analog Converters
AD9776A/AD9778A/AD9779A
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
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).
PRODUCT HIGHLIGHTS
1. Ultralow noise and intermodulation distortion (IMD)
enable high quality synthesis of wideband signals from
baseband to high intermediate frequencies.
2. A proprietary DAC output switching technique enhances
dynamic performance.
3. The current outputs are easily configured for various
single-ended or differential circuit topologies.
4. CMOS data input interface with adjustable setup and hold.
5. Novel 2×, 4×, and 8× interpolator/coarse complex
modulator allows carrier placement anywhere in DAC
bandwidth.
COMPLEX I AND Q
TYPICAL SIGNAL CHAIN
QUADRATURE
MODULATOR/
MIXER/
DC
AMPLIFIER
LO
DC
DIGITAL INTERPOLATION FILTERS
FPGA/ASIC/DSP
I DAC
Q DAC
POST DAC
ANALOG FILTER
A
AD9776A/AD9778A/AD9779A
Figure 1.
Rev. B
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