250mW Power Amplifer Platform with the XE1205

AN1205.04
ADVANCED COMMUNICATIONS & SENSING
FINAL
Application Note
AN1205.04
250mW Power Amplifier Platform with the XE1205
GENERAL DESCRIPTION
KEY PRODUCT FEATURES
The XE1205 is an integrated transceiver operating in the
433, 868 and 915 MHz license-free ISM (Industrial,
Scientific and Medical) frequency bands. This application
note describes how to take advantage of a low-cost
external Power Amplifier to reach an output power of up to
250 mW (+24dBm) at 915 MHz. A full bill of materials and
details of regulatory compliance with §CFR 47 Part15.247
is also provided.
APPLICATIONS
Š
Š
Š
Š
Long Distance Automatic Meter Reading
Alarm system
Asset tracking
Š
Š
Programmable RF output power: from 12 to 24 dBm
Š
Š
Š
Š
Low power receive mode: 14 mA
High Rx sensitivity: down to -121 dBm at 1.2 kbit/s,
-116 dBm at 4.8 kbits
Good transmitter efficiency: 250 mA typ. @ +24 dBm
902 to 928 MHz frequency range
Lowest-Cost Bill Of Materials: L-C based output filter
SUPPORT MATERIAL
Š
Š
Š
Schematic Drawing
Bill Of Materials
Gerber Files upon request
Long Range Telemetry
Please contact your Semtech representative.
Revision 1.0 / February 2008
©2008 Semtech Corp.
Page 1
www.semtech.com
AN1205.04
ADVANCED COMMUNICATIONS & SENSING
FINAL
Application Note
Table of Contents
Section
1.
2.
3.
Page
Board Description .................................................................................................................................................... 3
1.1.
Board Overview ............................................................................................................................................... 3
1.2.
Board Schematics............................................................................................................................................ 4
1.3.
PCB Layout...................................................................................................................................................... 5
1.4.
Bill Of Materials................................................................................................................................................ 5
Board Performance.................................................................................................................................................. 7
2.1.
Output Power over the ISM Band .................................................................................................................... 7
2.2.
Pout vs. Vcc ..................................................................................................................................................... 7
2.3.
Pout vs. Temperature ...................................................................................................................................... 8
2.4.
Spurious Emissions ......................................................................................................................................... 9
Conclusion ............................................................................................................................................................. 10
Table of Figures
Figure 1. Board Overview ................................................................................................................................................3
Figure 2. Schematic Diagram ..........................................................................................................................................4
Figure 3. PCB Top Layer .................................................................................................................................................5
Figure 4. PCB Bottom Layer............................................................................................................................................ 5
Figure 5. Pout over Frequency ........................................................................................................................................ 7
Figure 6. Output Power vs. Vcc....................................................................................................................................... 8
Figure 7. Power Consumption vs. Vcc ............................................................................................................................ 8
Figure 8. Spectral Purity DC-960 MHz ............................................................................................................................9
Figure 9. Spectral Purity 960 MHz - 10 GHz .................................................................................................................10
Revision 1.0 / February 2008
©2008 Semtech Corp.
Page 2
www.semtech.com
AN1205.04
250mW PA Platform with the XE1205
ADVANCED COMMUNICATIONS & SENSING
FINAL
Application Note
1. Board Description
This 250 mW high power transceiver design is based on Semtech's XE1205 ISM band transceiver and an NEC
NESG250134 SiGe RF transistor. Information about the NEC transistor can be found at the following websites:
www.ncsd.necel.com
www.cel.com
This high power Short Range Device design is implemented on a simple low-cost, two-layer FR4 substrate board. The
design is as small as 37 x 57 mm, and is intended to meet the regulatory requirements of the North American FCC Part
15.247 FHSS (Frequency Hopping Spread Spectrum) systems.
1.1. Board Overview
Figure 1. Board Overview
Figure 1 shows the reference design sub-divided into six different areas:
Š
XE1205 2-layer reference design (blue) - the output matching network of this stage has been modified to optimize
power transfer to the following (PA) stage.
Š
Interstage Matching (yellow) - performs the impedance transformation between the XE1205 and the PA and is
necessary to ensure stability.
Š
Š
Š
Power Amplifier (grey) - includes the PA (an NESG-250134) and its associated power supply biasing and decoupling.
Š
Antenna tank circuit and switch (white) - these components are taken from the original XE1205 reference design
(downloadable from the Semtech website). However, a higher power switch (Hittite HMC595) has been used to
accommodate the higher 250 mW output power.
PA Output match (red) - necessary to ensure that the optimal gain, linearity and efficiency are achieved.
Output Filter (purple) - required for harmonic rejection, to ensure regulatory compliance with §CFR 47 Part 15.247 of
the FCC regulations. The filter is based upon discrete components for minimum cost.
Revision 1.0 / February 2008
©2008 Semtech Corp.
Page 3
www.semtech.com
AN1205.04
250mW PA Platform with the XE1205
ADVANCED COMMUNICATIONS & SENSING
FINAL
Application Note
1.2. Board Schematics
Figure 2 shows the 250 mW board schematic diagram. For clarity, the sub-divisions of section 1.1 are reproduced here.
Note: For the components values, please consult the Bill Of Material (BOM), in section 1.4.
Figure 2. Schematic Diagram
Revision 1.0 / February 2008
©2008 Semtech Corp.
Page 4
www.semtech.com
AN1205.04
250mW PA Platform with the XE1205
ADVANCED COMMUNICATIONS & SENSING
FINAL
Application Note
1.3. PCB Layout
For low-cost and practicality, the reference design has been implemented on a 2-layer, 1.6mm-thick, FR4 substrate printed
circuit board. The design can be implemented on other thicknesses and other substrate materials keeping in mind the
following:
Š
Any change in board thickness or material will affect the impedance of the board, as will changes in track length or
thickness. The RF signal path will be especially susceptible to such changes. We recommend, where possible, the
design be kept as close as possible to the reference design.
Š
The application note RF Design Guidelines: PCB Layout and Circuit Optimization can be downloaded from the
Semtech website www.semtech.com if the users want to implement the reference design for their own application.
Figure 3 and Figure 4 below show the two PCB layers, top and bottom sides.
Figure 4. PCB Bottom Layer
Figure 3. PCB Top Layer
1.4. Bill Of Materials
The table below gives the values and characteristics of the components detailed in the schematic on section 1.2. It is
important to note that deviation from the specified components may result in a degradation of the circuit performances.
Revision 1.0 / February 2008
©2008 Semtech Corp.
Page 5
www.semtech.com
AN1205.04
250mW PA Platform with the XE1205
ADVANCED COMMUNICATIONS & SENSING
Table 1
FINAL
Application Note
Bill Of Materials at 915MHz
RefDes
MPN
Geom
Value
U1
VQFN48
XE1205
XE1205I074TRLF
U2
TMX S110
SMT 3.8x3.8
915MHz
U3
HMC595E
SC-70 6L
HMC595
NX3225DA 39MHz EXS00A-02557
SMD 3.2x2.5
39.0MHz
Q1
Q2
NESG250134
Power Minimold
NESG250134
D1
0603
1N4148
R1
0402
1k
R2
0402
1k
R3
0402
1k
R4
0402
680
R5
0402
1k
R6
0402
1k
R7
NC
R8
0402
0R
R9
0402
0R
R10
0402
330
R11
0402
0R
R434
NC
R869
NC
R915
0402
0R
C1
0603
33pF
C2
0603
1uF
C3
0603
1.8pF
C4
0603
1.2pF
C5
0603
1.2pF
C6
NC
C7
0603
2.2pF
C8
0603
33pF
C9
NC
C10
0402
1.5pF
C11
0402
10nF
C12
0402
1nF
C13
0603
1.2pF
C14
0603
33pF
C15
0402
1nF
C16
0402
1nF
C17
NC
C18
NC
C19
NC
C20
0603
1.2pF
C21
0603
33pF
C22
0603
1uF
C23
0603
33pF
C24
0603
68pF
C25
0603
10nF
C26
NC
C27
NC
C28
0603
3.3nF
C29
0603
33pF
C30
0603
10nF
C32
0603
1uF
C33
0603
1.8pF
C34
0603
3.9pF
C35
0603
33pF
C36
0603
0.47pF
C37
0603
2.2pF
C38
NC
C39
0603
2.2pF
C40
0603
2.2pF
C41
0402
Note 1
C42
0402
Note 1
L1
0603
10nH
L2
0603
47nH
L3
LQW18AN27NG00D
0603
27nH
L4
0402
5.6nH
L5
0402
18nH
L6
0603
18nH
L7
0603
3.3nH
L8
0603
0R
L9
0603
47nH
L10
0603
0R
L11
0603
0R
L12
0603
0R
L13
0603
47nH
L15
0603
3.3nH
L16
0603
6.8nH
L17
0603
2.7nH
SMA
50 Ohms
RF_IO
Note 1: C41 and C42 are ajusted to tune LO at nominal frequency of 915.000MHz
Revision 1.0 / February 2008
©2008 Semtech Corp.
Qty
1
1
1
1
1
1
1
1
1
1
1
1
0
1
1
1
1
0
0
1
1
1
1
1
1
0
1
1
0
1
1
1
1
1
1
1
0
0
0
1
1
1
1
1
1
0
0
1
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Page 6
Description
RF transceiver IC
SAW Bandpass Filter 915MHz
GaAs MMIC 3W T/R Switch
Crystal 39MHz CL=8pF
NPN SiGe RF Transistor
General purpose 1N4148 diode
Resistor (+/-5%)
Resistor (+/-5%)
Resistor (+/-5%)
Resistor (+/-1%)
Resistor (+/-5%)
Resistor (+/-5%)
Manufacturer
Semtech
Temex
Hittite
NDK
NEC
Resistor
Resistor
Resistor (+/-5%)
Resistor
Resistor
Capacitor NPO (+/-5%)
Capacitor Y5V (+80/-20%)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-5%)
Capacitor NPO (+/-0.25pF)
Capacitor X7R (+/-10%)
Capacitor X7R (+/-10%)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-5%)
Capacitor X7R (+/-10%)
Capacitor X7R (+/-10%)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-5%)
Capacitor Y5V (+80/-20%)
Capacitor NPO (+/-5%)
Capacitor NPO (+/-5%)
Capacitor X7R (+/-10%)
Capacitor X7R (+/-10%)
Capacitor NPO (+/-5%)
Capacitor X7R (+/-10%)
Capacitor Y5V (+80/-20%)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-5%)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-0.25pF)
Capacitor NPO (+/-0.25pF)
Multilayer inductor
Multilayer inductor
Wirewound
MURATA
Multilayer inductor
Multilayer inductor
Multilayer inductor
Multilayer inductor
Resistor
Multilayer inductor
Resistor
Resistor
Resistor
Multilayer inductor
Multilayer inductor
Multilayer inductor
Multilayer inductor
SMA Straight Jack Receptacle for PCB mount
www.semtech.com
AN1205.04
250mW PA Platform with the XE1205
ADVANCED COMMUNICATIONS & SENSING
FINAL
Application Note
2. Board Performance
This application was designed to meet the conducted output power requirement of 250 mW (i.e. +24 dBm) over the 902928 MHz North American ISM band. This circuit will deliver the specified power over the following ranges:
Š
Š
Š
Š
Pout=+24 dBm
Vcc range from 2.4 to 3.6 V
Temperature range from -40 to +85°C
Output Power derating along all operating conditions: +/-2 dB
2.1. Output Power over the ISM Band
Figure 5 shows the variation in ouput power of the XE1205 power amplifier circuit over the 902 to 928 MHz ISM band. The
measured performance guarantees a constant link budget over the whole band of operation.
Output Pow er over the Frequency Band
Vcc=3.3V, m axim um pow er level
26
Pout [dBm]
25
24
23
22
21
20
902 904 906 908 910 912 914 916 918 920 922 924 926 928
Frequency [MHz]
Figure 5. Pout over Frequency
2.2. Pout vs. Vcc
Figure 6 below illustrates the reference design performance versus the supply voltage range for each of the output power
settings of XE1205. Figure 7 then shows the total dissipation of the amplifier plus XE1205 over the same range of test
conditions.
Revision 1.0 / February 2008
©2008 Semtech Corp.
Page 7
www.semtech.com
AN1205.04
250mW PA Platform with the XE1205
ADVANCED COMMUNICATIONS & SENSING
Application Note
FINAL
Pout vs. Vcc
30.0
25.0
Pout [dBm]
20.0
15.0
10.0
5.0
0.0
3
3.15
3.3
3.45
3.6
Vcc [V]
"11"
"10"
"01"
"00"
Figure 6. Output Power vs. Vcc
Icc vs. Vcc
350
300
Icc [mA]
250
200
150
100
50
0
3
3.15
3.3
3.45
3.6
Vcc [V]
"11"
"10"
"01"
"00"
Figure 7. Power Consumption vs. Vcc
2.3. Pout vs. Temperature
With the combination of D1 and R10, the design exhibits a very good stability of the output power over the temperature
range, i.e. from -40 to +85°C:
Š
Š
Š
at 25°C, 3.3V: +25.2 dBm
at -40°C, 3.3V: +25.8 dBm
at +85°C, 3.3V: +23.7 dBm
Revision 1.0 / February 2008
©2008 Semtech Corp.
Page 8
www.semtech.com
AN1205.04
250mW PA Platform with the XE1205
ADVANCED COMMUNICATIONS & SENSING
Application Note
FINAL
2.4. Spurious Emissions
The North American regulatory constraints applicable to this circuit are given in the FCC Part 15.247 section.
Š
If the spurious emissions fall inside the restricted bands (listed under section 15.205a), their level should be below 200
microvolts per meter measured at a 3 meter distance, if their frequency is below 960 MHz.
Š
Spurious emissions that fall inside restricted bands over 960 MHz should respect a field strength limit of 500 microvolts
per meter at a 3 meter distance.
Š
For any other spurii, their level should be 20 dB below that of the carrier (i.e. -20dBc).
The measured radiated response will, of course, depend upon the type of antenna employed and the screening employed.
Here, an equivalent conducted measurement is performed to assess compliance with the FCC limits. We define these
limits as:
Š
Š
200 uV/m @ 3m correspond to -49.2 dBm EIRP limit below 960 MHz
500 uV/m @ 3m correspond to -41.2 dBm EIRP limit above 960 MHz
These limits are shown in red on Figure 8 and Figure 9, assuming the use of a 0 dBi gain antenna.
Spectral Purity from DC to 960MHz
30
20
10
Power [dBm]
0
-10
-20
-30
FRF-4*FXO
-40
-50
4*FXO
-60
0
100
200
300
400
500
600
700
800
900
Frequency [MHz]
Figure 8. Spectral Purity DC-960 MHz
A spurious emission at 4 times the crystal oscillator frequency (i.e. 156 MHz +/- 100ppm typ.) is highlighted on Figure 8.
Referring to the FCC Part 15.205(a), which lists the restricted bands of operation, the 200uV/m @ 3 meters limit will apply
from 156.52475 to 156.52525 MHz. This is very narrow and, since the crystal drift is not expected to be over +/-100ppm,
this spur will not fall inside the restricted band.
Revision 1.0 / February 2008
©2008 Semtech Corp.
Page 9
www.semtech.com
AN1205.04
250mW PA Platform with the XE1205
ADVANCED COMMUNICATIONS & SENSING
Application Note
FINAL
Spectral Purity from 960MHz to 10GHz
0
H2
-10
Power [dBm]
-20
-30
H7
-40
H4
H5
-50
-60
960
1960
2960
3960
4960
5960
6960
7960
8960
9960
Frequency [MHz]
Figure 9. Spectral Purity 960 MHz - 10 GHz
The harmonic frequencies of the transmitter are highlighted on Figure 9. Their level is below the specified limit.
Notes:
Š
Semtech suggests the user also read the accompanying application note: FCC Regulations for ISM Band Devices:
902-928 MHz. This describes in detail the North American FCC restriction on ISM band Short Range Devices. It can be
downloaded from www.semtech.com
Š
The rejection of harmonic frequencies on this design, has been achieved through lumped elements, to enable the
lowest-cost BOM. For size constrained applications, the filter (outlined in purple on Figure 1) can be replaced by a
multilayer LTCC (Low Temperature Co-Fired Ceramic) low-pass filter. This type of filter exhibits a very good harmonic
response within a single 0603 footprint. An example is the 0915LP15B026 from Johanson Technology. It offers a
minimum attenuation of 30 dB on the 2nd and 3rd harmonics (actually more than 40dB). Additional information can be
found at www.johansontechnology.com.
3. Conclusion
A reference design for a single-stage 250 mW power amplifier in conjunction with XE1205 has been presented. This
reference design uses a low-cost lumped element filter and is intended for operation in the 902-928 MHz ISM band.
Applications of this circuit include, for instance, long range Automatic Meter Reading or two-way car alarm systems.
Revision 1.0 / February 2008
©2008 Semtech Corp.
Page 10
www.semtech.com
AN1205.04
ADVANCED COMMUNICATIONS & SENSING
FINAL
Application Note
© Semtech 2008
All rights reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The
information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable
and may be changed without notice. No liability will be accepted by the publisher for any consequence of its use. Publication
thereof does not convey nor imply any license under patent or other industrial or intellectual property rights. Semtech assumes
no responsibility or liability whatsoever for any failure or unexpected operation resulting from misuse, neglect improper
installation, repair or improper handling or unusual physical or electrical stress including, but not limited to, exposure to
parameters beyond the specified maximum ratings or operation outside the specified range.
SEMTECH PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN
LIFE-SUPPORT APPLICATIONS, DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF
SEMTECH PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE UNDERTAKEN SOLELY AT THE CUSTOMER’S
OWN RISK. Should a customer purchase or use Semtech products for any such unauthorized application, the customer shall
indemnify and hold Semtech and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims,
costs damages and attorney fees which could arise.
Contact information
Semtech Corporation Advanced Communications & Sensing Products
E-mail: [email protected]
[email protected]
Internet: http://www.semtech.com
USA
200 Flynn Road, Camarillo, CA 93012-8790.
Tel: +1 805 498 2111 Fax: +1 805 498 3804
FAR EAST
12F, No. 89 Sec. 5, Nanking E. Road, Taipei, 105, TWN, R.O.C.
Tel: +886 2 2748 3380 Fax: +886 2 2748 3390
EUROPE
Semtech Ltd., Units 2 & 3, Park Court, Premier Way, Abbey Park Industrial Estate, Romsey, Hampshire, SO51 9DN.
Tel: +44 (0)1794 527 600 Fax: +44 (0)1794 527 601
ISO9001
CERTIFIED
Revision 1.0 / February 2008
©2008 Semtech Corp.
Page 11
www.semtech.com
Similar pages