Circuit Note

CN-0134

Circuits from the Lab™ tested circuit designs address

common design challenges and are engineered for

quick and easy system integration. For more information

and/or support, visit www.analog.com/CN0134.

Devices Connected/Referenced

ADF4350

Fractional-N PLL IC with Integrated VCO

ADL5375

Wideband Transmit Modulator

ADP150

Low Noise 3.3 V LDO

ADP3334

Low Noise Adjustable LDO

Broadband Low Error Vector Magnitude (EVM) Direct Conversion Transmitter

Rev. B

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

suitabilityandapplicabilityforyouruseandapplication.Accordingly,innoeventshallAnalogDevices

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EVALUATION AND DESIGN SUPPORT

Circuit Evaluation Boards

CN-0134 Evaluation Board (CFTL-CN0134-EVALZ)

Design and Integration Files

Schematics, Layout Files, Bill of Materials

CIRCUIT FUNCTION AND BENEFITS

This circuit is a complete implementation of the analog portion

of a broadband direct conversion transmitter (analog baseband

in, RF out). RF frequencies from 500 MHz to 4.4 GHz are

supported through the use of a PLL with a broadband

integrated voltage controlled oscillator (VCO). Harmonic

filtering of the LO from the PLL ensures excellent quadrature

accuracy.

22nF

10nF

330nF

180Ω

82Ω

IBBP

IBBN

LOIP

LOIN

QBBP

QBBN

ADF4350

3.3V

AGND

1nF

1nF

4.7kΩ

LE

DATA

CLK

10

28

16

29

1

2

3

22

8

31

9

11 18 21

27

51Ω

14

15

17

20

7

26

6

32

5

SW

4

ADL5375

RFOUT

13

12

QUADRATURE

PHASE

SPLITTER

I/Q SMA INPUTS

I/Q SMA INPUTS

ADP150

1µF

1µF

5.5V

5.0V

VPS1, VPS2

ADP3334

1µF

1µF

5.5V

Figure 1. Direct Conversion Transmitter (Simplified Schematic: All Connections and Decoupling Not Shown)