Circuit Note

CN-0243

Circuits from the Lab™ reference circuits are

engineered and testedfor quickandeasy

system integrationtohelpsolvetoday’sanalog,

mixed-signal, and RF design challenges.

For more informationand/or support,visit

www.analog.com/CN0243.

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

Rev.0

CircuitsfromtheLab™circuitsfromAnalogDeviceshavebeendesignedandbuiltbyAnalogDevices

engineers. Standard engineering practices have been employed in the design and construction of

eachcircuit,andtheirfunctionandperformancehavebeentestedandverifiedinalabenvironmentat

room temperature. However, you are solely responsible for testing the circuit and determining its

suitabilityandapplicabilityforyouruseandapplication.Accordingly,innoeventshallAnalogDevices

be liable for direct, indirect, special, incidental, consequential or punitive damages due to any cause

whatsoeverconnectedtotheuseofanyCircuitsfromtheLabcircuits. (Continuedonlastpage)

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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

DUAL MODULUS PLL

WITH ON CHIP VCO

EXTERNAL LOOP

FILTER

EXTERNAL LOOP

FILTER

AD9516

AD9122

ADRF6702

PLL REFERENCE

INPUT

PROGRAMMABLE DIVIDER

PROGRAMMABLE DIVIDER

OPTIONAL

EXTERNAL

2 × LO (I/O)

INTERNALLY

GENERATED

2 × LO

ADRF6702

RF OUTPUT

AD9122 DAC

SAMPLE CLOCK

IDAC

I CHANNEL PASSIVE INTERFACE FILTER

QDAC

Q CHANNEL PASSIVE INTERFACE FILTER

16-BIT

DATA BUS

(I)

16-BIT

DATA BUS

(Q)

32-BIT NCO

2×/4×/8×

INTERPOLATION

FILTERS

2×/4×/8×

INTERPOLATION

FILTERS

INTERNAL LO

SYNTHESIZER/PLL

INTERNAL

VCO

÷2

MODULATOR

CORE

PLL CORE (PFD, CHARGE

PUMP, DIVIDER)

Figure 1. AD9122, ADRF6702, and AD9516 Used in a High Dynamic Range Transmitter