ANALOG DEVICES AN-1151 Service Manual

AN-1151

Application Note

Parameter

Description

10634-001

One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: [phone] • Fax: [phone] • www.analog.com

Using a Johanson 2450BM14E0007 Impedance-Matched, Integrated Filter Balun

with the ADF7241 and ADF7242

by Mary O’Keefe

INTRODUCTION

This application note describes the use and performance achieved
using the Johanson Technology, Inc., 2450BM14E0007 impedance­matched (complex differential impedance value) filter balun with
the ADF7241 or ADF7242 2.4 GHz RF transceivers. The filter
balun from Johanson Technology effectively reduces the RF
front-end component count and layout space. This balun is 100%
RF tested by Johanson Tec hnol og y. The Additional Information
from Johanson Technology section provides more insight about
how harmonic emissions are attenuated, as well as further details
about the balun component.

Table

1. Key Parameters of the Filter Balun

Part Number 2450BM14E0007
Frequency 2400 MHz to 2500 MHz
Unbalanced Port Impedance 50 Ω
Balanced Port Impedance Matched to ADF7241/ADF7242

RF port impedance

TYPICAL PERFORMANCE D ATA

Tabl e 2 shows typical performance data obtained from the

ADF7241 and ADF7242 using the 2450BM14E0007 impedance-

matched filter balun.

EVALUATION BOARD LAYO UT

An outline of the RF board layout is shown in Figure 1. Gerber
files of the board layout are available on the Analog Devices, Inc.,

ADF7242 evaluation board product website. Because the imped-

ance seen by the balun is inherently dependent on the layout,
it is recommended to follow the EVAL-ADF724xDB3Z layout
as shown in the Gerber files as closely as possible for optimum
performance.

The board schematic is shown in Figure 2. Note that the C7 and
C8 capacitors are required for power amplifier stability, and the
specified 10 nF value should be used.

2. Typical Performance of the ADF7241 and ADF7242

Table
Using the 2450BM14E0007 Filter Balun

Parameter Value

Tx Output Power 3 dBm
Harmonics

4.9 GHz −50 dBm

7.35 GHz −47 dBm

Figure 1. EVAL-ADF724xDB3Z Board Layout Highlighting Balun Location

Rev. 0 | Page 1 of 8

AN-1151 Application Note

TABLE OF CONTENTS

Introduction ...................................................................................... 1

Typical Performance Data ............................................................... 1

Evaluation Board Layout ................................................................. 1

REVISION HISTORY

5/12—Revision 0: Initial Version

Revision History ................................................................................2

Evaluation Board Schematic ............................................................3

Additional Information from Johanson Technology ....................4

Rev. 0 | Page 2 of 8

Application Note AN-1151

10634-002

EVALUATION BOARD SCHEMATIC

Figure 2. EVAL-ADF724xDB3Z Schematic

Rev. 0 | Page 3 of 8