CN-0243 Datasheet, PDF (1/8 Pages) Analog Devices – High Dynamic Range RF Transmitter Signal Chain Using Single External Frequency Reference for DAC Sample Clock and IQ Modulator LO Generation

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Circuit Note
CN-0243
Devices Connected/Referenced
ADRF6702
1200 MHz to 2400 MHz Quadrature
Modulator with1550 MHz to 2150 MHz
Fractional-N PLL and Integrated VCO
AD9122
Dual, 16-Bit, 1230 MSPS, TxDAC®
AD9516-0/AD9516-1/
AD9516-2/AD9516-3/
AD9516-4
Clock Generator with Integrated VCO
with Various Frequency Range Options
from 1.45 GHz to 2.95 GHz
High Dynamic Range RF Transmitter Signal Chain Using Single External Frequency
Reference for DAC Sample Clock and IQ Modulator LO Generation
EVALUATION AND DESIGN SUPPORT
Circuit Evaluation Boards
CN-0243 Circuit Evaluation Board (EVAL-CN0243-EB1Z)
Design and Integration Files
Schematics, Layout Files, Bill of Materials
CIRCUIT FUNCTION AND BENEFITS
The combination of the ADRF6702 IQ modulator and the
AD9122 16-bit dual 1.2 GSPS TxDAC has the dynamic range
necessary for a modern high level QAM or OFDM based
wireless transmitter as shown in Figure 1. The dynamic range
EXTERNAL
FREQUENCY
REFERENCE
INPUT
EXTERNAL LOOP
FILTER
DUAL MODULUS PLL
WITH ON CHIP VCO
AD9516
ADRF6702
PLL REFERENCE
INPUT
PROGRAMMABLE DIVIDER
EXTERNAL LOOP
FILTER
PLL CORE (PFD, CHARGE
PUMP, DIVIDER)
PROGRAMMABLE DIVIDER
AD9122
32-BIT NCO
AD9122 DAC
SAMPLE CLOCK
INTERNAL
VCO
INTERNAL LO
SYNTHESIZER/PLL
OPTIONAL
EXTERNAL
2 × LO (I/O)
INTERNALLY
GENERATED
2 × LO
÷2
RF OUTPUT
MODULATOR
CORE
ADRF6702
16-BIT
DATA BUS
(I)
2×/4×/8×
INTERPOLATION
FILTERS
IDAC
I CHANNEL PASSIVE INTERFACE FILTER
16-BIT
DATA BUS
(Q)
2×/4×/8×
INTERPOLATION
FILTERS
QDAC
Q CHANNEL PASSIVE INTERFACE FILTER
Figure 1. AD9122, ADRF6702, and AD9516 Used in a High Dynamic Range Transmitter
Rev.0
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