AD9121 Datasheet, PDF (1/61 Pages) Analog Devices – TxDAC+ Digital-to-Analog Converter

Data Sheet
Dual, 14-Bit, 1230 MSPS,
TxDAC+ Digital-to-Analog Converter
AD9121
FEATURES
Flexible LVDS interface allows word or byte load
Single-carrier W-CDMA ACLR = 82 dBc at 122.88 MHz IF
Analog output: adjustable 8.7 mA to 31.7 mA,
R_L = 25 Ω to 50 Ω
Integrated 2×/4×/8× interpolator/complexmodulatorallows
carrier placement anywhere in the DAC bandwidth
Gain, dc offset, and phase adjustment for sideband
suppression
Multiple chip synchronization interfaces
High performance, low noise PLL clock multiplier
Digital inverse sinc filter
Low power: 1.5 W at 1.2 GSPS, 800 mW at 500 MSPS,
full operating conditions
72-lead, exposed paddle LFCSP
APPLICATIONS
Wireless infrastructure
W-CDMA, CDMA2000, TD-SCDMA, WiMAX, GSM, LTE
Digital high or low IF synthesis
Transmit diversity
Wideband communications: LMDS/MMDS, point-to-point
GENERAL DESCRIPTION
The AD9121 is a dual, 14-bit, high dynamic range digital-to-
analog converter (DAC) that provides a sample rate of 1230 MSPS,
permitting multicarrier generation up to the Nyquist frequency.
The AD9121 TxDAC+® includes features optimized for direct
conversion transmit applications, including complex digital mod-
ulation, and gain and offset compensation. The DAC outputs
are optimized to interface seamlessly with analog quadrature
modulators, such as the ADL537x F-MOD series from Analog
Devices, Inc. A 4-wire serial port interface provides for program-
ming/readback of many internal parameters. Full-scale output
current can be programmed over a range of 8.7 mA to 31.7 mA.
The AD9121 comes in a 72-lead LFCSP.
PRODUCT HIGHLIGHTS
1. Ultralow noise and intermodulation distortion (IMD)
enable high quality synthesis of wideband signals from
baseband to high intermediate frequencies (IF).
2. Proprietary DAC output switching technique enhances
dynamic performance.
3. Current outputs are easily configured for various single-
ended or differential circuit topologies.
4. Flexible LVDS digital interface allows the standard 28-wire
bus to be reduced to one-half of the width.
COMPANION PRODUCTS
IQ Modulators: ADL5370, ADL537x family
IQ Modulatorswith PLLand VCO: ADRF6701, ADRF670x family
Clock Drivers: AD9516, AD951x family
Voltage Regulator Design Tool: ADIsimPower
TYPICAL SIGNAL CHAIN
COMPLEX BASEBAND
COMPLEX IF
RF
DC
f_IF
DIGITAL
BASEBAND
PROCESSOR
2
SIN
COS
2
AD9121
NOTES
1. AQM = ANALOG QUADRATURE MODULATOR.
2/4
I DAC
2/4
Q DAC
Figure 1.
LO – f_IF
ANTIALIASING
FILTER
AQM ^PA
LO
Rev. B
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