Application Note "Antenna for Japanese Market"

A pp . Not e , V 1. 0 , No v 20 0 3
Application Note TDx5101x
Low P ow er An te nna Bo ard fo r Jap ane se
Market
Ver s i on 1 .0
W i re l e s s C o m mu n i c a t i o n
N e v e r
s t o p
t h i n k i n g .
Edition 2003-11-26
Published by Infineon Technologies AG,
St.-Martin-Strasse 53,
81669 München, Germany
© Infineon Technologies AG 2004.
All Rights Reserved.
Attention please!
The information herein is given to describe certain components and shall not be considered as a guarantee of
characteristics.
Terms of delivery and rights to technical change reserved.
We hereby disclaim any and all warranties, including but not limited to warranties of non-infringement, regarding
circuits, descriptions and charts stated herein.
Information
For further information on technology, delivery terms and conditions and prices please contact your nearest
Infineon Technologies Office in Germany or the Infineon Technologies Companies and our Infineon Technologies
Representatives worldwide (www.infineon.com).
Warnings
Due to technical requirements components may contain dangerous substances. For information on the types in
question please contact your nearest Infineon Technologies Office.
Infineon Technologies Components may only be used in life-support devices or systems with the express written
approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the failure
of that life-support device or system, or to affect the safety or effectiveness of that device or system. Life support
devices or systems are intended to be implanted in the human body, or to support and/or maintain and sustain
and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other persons may
be endangered.
A pp . Not e , V 1. 0 , No v 20 0 3
Application Note TDx5101x
Low P ow er An te nna Bo ard fo r Jap ane se
Market
Ver s i on 1 .0
W i re l e s s C o m mu n i c a t i o n
N e v e r
s t o p
t h i n k i n g .
Application Note TDx5101x
Confidential
Revision History:
2003-11-26
Previous Version:
Page
V 1.0
none
Subjects (major changes since last revision)
We Listen to Your Comments
Any information within this document that you feel is wrong, unclear or missing at all?
Your feedback will help us to continuously improve the quality of this document.
Please send your proposal (including a reference to this document) to:
[email protected]
Application Note TDx5101x
Table of Contents
Page
1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2
2.1
2.2
2.3
2.4
TDK5101F Antenna-Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Measurement Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3
TDx5101 Antenna-Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4
4.1
4.2
Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Output Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
App.Note
5
V 1.0, 2003-11-26
Application Note TDx5101x
Introduction
1
Introduction
In Japan operation of RF-Transmitters is allowed without any license if the field-strength
at 3m distance is below the limits given in Figure 1:
Figure 1
Japanese Radio Regulations
As can be easily seen the maximum field strength at 315MHz is 500 µV/m, which is quite
low. So the output power of our TDx5101x-transmitters has to be reduced by more than
20dB using a special design of the antenna-matching circuit. Also care has to be taken
on the harmonic emissions since the maximum field strength is 35 µV/m there. This
requires some additional filtering.
App.Note
6
V 1.0, 2003-11-26
Application Note TDx5101x
TDK5101F Antenna-Board
2
TDK5101F Antenna-Board
2.1
Schematic
Figure 2
App.Note
Antenna Board Schematic
7
V 1.0, 2003-11-26
Application Note TDx5101x
TDK5101F Antenna-Board
2.2
Layout
Figure 3
AntennaBoard_TOP
Figure 4
AntennaBoard_Bottom
App.Note
8
V 1.0, 2003-11-26
Application Note TDx5101x
TDK5101F Antenna-Board
2.3
Bill of Materials
Table 1
BOM Table
FSK-Mode
ASK-Mode
R1
open
open
R2
0R
0R
0603, SMD-Jumper
R3
0R
4k7
0603, +/-5%
R4
open
open
R5
0R
0R
0603, SMD-Jumper
R6
0R
4k7
0603, +/-5%
R7
82k
open
0603, +/-5%
R8
4k7
4k7
0603, +/-1%
R9
15k
15k
0603, +/-5%
C1
15p
15p
0603, C0G, +/-1%
C2
6p8
6p8
0603, C0G, +/-0,1p
C3
open
open
C4
open
open
C5
open
1nF
C6
10n
10n
0603, X7R, +/-10%
C7
330p
330p
0603, C0G, +/-10%
C8
18p
18p
0603, C0G, +/-1%
C9
10p
10p
0603, C0G, +/-1%
C10
47n
47n
0603, X7R, +/-10%
L1
0R
0R
0603, SMD-Jumper
L2
39n
39n
0603, EPCOS SIMID, +/-2%,
B82496C3390G
S1
push-button
push-button
STTSKHMPW, ALPS
Q1
9843.75 kHz,
CL=12pF
9843.75 kHz,
CL=12pF
Tokyo Denpa TSS-3B 9843.75 kHz
Spec.No. 1053-921
IC1
TDK5101F
TDK5101F
P-TSSOP-10
IC2
HCS360
HCS360
SO8, Microchip
BAT1
battery-holder
battery-holder
HU2031-1, Renata
App.Note
0603, X7R, +/-10%
9
V 1.0, 2003-11-26
Application Note TDx5101x
TDK5101F Antenna-Board
2.4
Measurement Results
Table 2
Measurement Results
Fundamental:
400 µV/m
Harmonics:
<35 µV/m
Current Consumption:
5.4 mA
App.Note
10
V 1.0, 2003-11-26
Application Note TDx5101x
TDx5101 Antenna-Board
3
TDx5101 Antenna-Board
The antenna board of the TDx5101 (16-pin-package) can be found in the specification
of the TDA5101. However, investigations revealed that the PA-biasing-resistor R4 has
to be changed from 1 kOhm to 4.7 kOhm in order to comply with Japanese Radio
Regulations.
App.Note
11
V 1.0, 2003-11-26
Application Note TDx5101x
Design Considerations
4
Design Considerations
4.1
Output Power
Figure 5 shows the effective radiated power as a function of the biasing-resistor.
Figure 5
Effective Radiated Power as a function of the biasing resistor
On our low-power-evalboards for the Japanese Market a PA-biasing-resistance of
4.7 kOhm is used.
Above 9 kOhm the output power is not dependant on the biasing resistor any more due
to RF-leakage. That’s why the PA-biasing-resistance must not exceed 6.8 kOhm in order
to avoid this operating region.
4.2
Stability
The evalboards described above are stable over mass-production.
However, if less efficient antennas are used in the application, the PA-biasing-resistor
would have to be decreased in order to compensate the additional losses in the antenna.
When using a biasing resistor below 3.3 kOhm, an additional resistor of approximately
18 Ohm has to be used in series to the antenna loop in order to damp spurious
resonances.
App.Note
12
V 1.0, 2003-11-26
w w w . i n f i n e o n . c o m
Published by Infineon Technologies AG
Similar pages