AN-1309
APPLICATION NOTE
One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
A Range Extension Reference Design Using the ADF7023 and RFFM6901
915 MHz ISM Band Transmit Receive Module with Diversity Switch
by Stephen Hinchy
INTRODUCTION
For situations where customers want to extend the range of the
ADF7023 ISM band transceiver, this application note describes
a reference design that enables an improvement of almost
20 dB on the overall link budget. In a line of sight scenario that
is not interference limited, this equates to a range increase of
approximately 6 to 7 times.
This transceiver is suitable for circuit applications that operate
under the European ETSI EN300-220, the North American
FCC (Part 15), the Chinese short-range wireless regulatory
standards, or other similar regional standards. Data rates from
1 kbps to 300 kbps are supported
This design consists of an ADF7023 transceiver from Analog
Devices, Inc., and an RFFM6901 front-end module (FEM) from
RFMD, Inc. The design is suitable for operation in the 902 MHz
to 928 MHz ISM band and complies with FCC regulations.
The RFFM6901 is a single chip front-end module for
application in the 868 MHz and 915 MHz ISM bands. The
RFFM6901 addresses the need for aggressive size reduction for
typical portable equipment RF front-end designs and greatly
reduces the number of components outside of the core chipset
thus minimizing the footprint and assembly cost of the overall
solution. The RFFM6901 contains an integrated 1 W PA, dual
port diversity antenna switch, LNA with bypass mode, and
matching components. The RFFM6901 is packaged in a 32-pin,
6.0 mm × 6.0 mm × 1.2 mm over-molded laminate package.
About the RFFM6901
About the ADF7023
The ADF7023 is a very low power, high performance, highly
integrated 2FSK/GFSK/OOK/MSK/GMSK transceiver. It
is designed for operation in the 862 MHz to 928 MHz and
431 MHz to 464 MHz frequency bands, which cover the
worldwide license-free ISM bands at 433 MHz, 868 MHz, and
915 MHz.
VDDRFBAT1
VDDRFBAT2
VDD 3.3V
PA_VCC1
VDIG
ADF7023
PA_VCC2
LNA_VCC
VDD 4V
RFFM6901 DS
CTL4
CTL1
CTL3
CTL5
CTL2
LNA
BALUN
ATB1
ATB2
LNA
PA2
CTL3
CTL4
Figure 1. Functional Block Diagram
Rev. A | Page 1 of 8
12322-001
PA1
PA
AN-1309
Application Note
TABLE OF CONTENTS
Introduction ...................................................................................... 1
Reference Design Description .........................................................4
Revision History ............................................................................... 2
Mode Control of RFFM6901 with ADF7023 ............................4
General Operation and Performance Data ................................... 3
Reference Design Schematics and Artwork ...................................5
General Operating Conditions ................................................... 3
Recommended PCB Layout .........................................................6
Typical Performance Data ........................................................... 3
Bill of Materials ..................................................................................7
FCC Compliance .......................................................................... 3
REVISION HISTORY
5/14—Rev. 0 to Rev. A
Changes to Table 2 ............................................................................ 3
5/14—Revision 0: Initial Version
Rev. A | Page 2 of 8
Application Note
AN-1309
GENERAL OPERATION AND PERFORMANCE DATA
This section describes the general operating conditions and
typical performance realized when using these devices together.
Further details regarding the performance of each device are
available in the product data sheets.
Typical performance data is taken as an average of eight
different EVAL-ADF7023-RFFM6901 Revision C evaluation
boards tested at room temperature with 3.3 V applied to the
ADF7023 and 4 V applied to the RFFM6901.
GENERAL OPERATING CONDITIONS
Table 1. General Operation Conditions
Parameter
Frequency Range
Supply Voltage, ADF7023
Supply Voltage, RFFM6901
Temperature Range
Min
902
Typ
Max
928
3.3
4.0
−40
+85
Unit
MHz
V
V
°C
Table 2. Typical Performance Data
Parameter
Maximum Transmit Power
Harmonics at 30 dBm Tx
Power
2nd Harmonic
3rd Harmonic
4th Harmonic
5th Harmonic
Receiver Sensitivity
200 kbps
Current Consumption
Tx Current at 30 dBm
Rx
Bypass
Sleep
Typ
30
Unit
dBm
Test Conditions
−18
−43
−56
−65
dBm
dBm
dBm
dBm
Conducted
Conducted
Conducted
Conducted
−106.7
dBm
10−3 BER FSK (fDEV
50 kHz), 915 MHz
650
21
mA
mA
0.5
mA
TYPICAL PERFORMANCE DATA
FCC COMPLIANCE
All test results were carried out on a test board, the EVALADF7023-RFFM6901 Revision C evaluation board.
Frequency hopping systems in the 902 MHz to 928 MHz
frequency band in the United States are subject to FCC Part 15
regulations. FCC Part 15.247 allows for transmission at up to
1 W (30 dBm) provided at least 50 frequency hopping channels
are used, the 20 dB bandwidth of the hopping channel is less
than 250 kHz, and the average time of occupancy on any
frequency is no greater than 0.4 seconds in a 20 second period.
The reference design described in this application note passed
FCC Part 15.247 radiated harmonics precompliance testing
at +30 dBm output power. Testing was carried out at both
100 kbps and 300 kbps for a 255-byte packet transmitted every
100 ms. No external SAW filter was used. RF shielding may be
required for other data rates, packet lengths, or if layout changes
are made to the reference design.
Rev. A | Page 3 of 8
AN-1309
Application Note
REFERENCE DESIGN DESCRIPTION
The reference design consists of an ADF7023 from Analog
Devices and an RFFM6901 front-end module from RFMD. This
design is applicable for the 915 MHz ISM band and is capable
of delivering +30 dBm output power and increasing receive
sensitivity. This specific configuration enables you to select a
number of modes.
In this reference design, the default power supply connections
for +30 dBm operation in transmit are as follows:
•
•
•
The ADF7023 is supplied at 3.3 V via the VDDBAT1 and
VDDBAT2 pins.
The LNA_VCC pin of the RFFM6901 is also supplied at
3.3 V.
The VDIG, PA_VCC1, and PA_VCC2 pins of the
RFFM6901 are supplied at 4 V.
However, if +27 dBm transmit power is required, a common
3.0 V to 3.3 V supply can be connected to both the ADF7023
and RFFM6901 power supply pins. For further information on
the operation of the RFFM6901 in this mode of operation,
consult the RFFM6901 data sheet.
For this reference design, it is recommend to use the RFFM6901
high bias mode in Receive and the low bias mode in Transmit.
Refer to the following subsection for how to configure the
reference design for these modes of operation. Other modes of
operation are also available (see Table 3) and are described in
the RFFM6901 data sheet.
MODE CONTROL OF RFFM6901 WITH ADF7023
The reference design is capable of a number of modes
dependent on specific user requirements. Table 3 summarizes
these modes and settings. The primary operation of the
RFFM6901 is controlled via the ADF7023 ATB ports thus
easing the load on the host processor. CTL 5 selects low or high
bias while CTL2 is the Tx/Rx select. These are controlled via
ATB 1 and ATB 2, respectively. CTL3 powers on or off the LNA
and CTL4 is the power-down pin; these pins can be controlled
via your host processor GPIO. If Rx bypass is not required, then
CTL 3 can be tied to CTL2 via a resistor. CTL1 is the antenna
select pin and is tied to ground in this design which is
configured for single antenna operation. Table 3 describes the
different modes and how they are controlled including register
writes from the ADF7023 where appropriate.
CTL2 and CTL5 are controlled via the ADF7023 ATB 1 and
ATB 2 GPIOs. The configuration of these pins is described in
the ADF7023 data sheet. In summary, Register 0x139,
Bit 7 controls the logic level drive at these pins. For this design,
it is recommended to set this to 3.3 V; this is established by
writing 0x139 = 0x00. Register 0x11A configures the logic table
for ATB1 and ATB2 and, once set, the ADF7023 state controls
the logic high or low at these pins. Thus, once Register 0x139
and Register 0x11A of the ADF7023 are configured, then the
state of the RFFM6901 is controlled by the ADF7023. This is
summarized in Table 3.
Table 3. Mode Control
System State
Power-Down/Sleep
Tx 1 (High Gain)
RFFM 6901
State
Power down
Tx high bias
ADF7023
State
Sleep
PHY_Tx
Tx 2 (Low Gain)
Tx low bias
PHY_Tx
Rx 1 (High Gain)
Rx high bias
PHY_Rx
Rx Bypass
Rx bypass
PHY_Rx
ADF7023 Register
Settings
Don’t care
0x139 = 0x00 and
0x11A = 0x43
0x139 = 0x00 and
0x11A = 0x42
0x139 = 0x00 and
0x11A = 0x42/43
0x139 = 0x00 and
0x11A = 0x42/43
CTL2 and CTL5 (Controlled via
Register Settings and ADF7023 State)
Don’t care
CTL2 = Low; CTL5 = High
CTL3
Don’t care
Low
CTL4
Low
High
CTL2 = Low; CTL5 = Low
Low
High
CTL2 = High; CTL5 = Low
High
High
CTL2 = High; CTL5 = Low
Low
High
Rev. A | Page 4 of 8
C10
CTL2
C11
CTL3
R5
C12
CTL4
PA_VCC1
CTL5
C4
CTL4
CTL3
CTL2
CTL1
GND
NC
GND
RFIO
C8
C18
RFFM6901
GND
V_D IG
GND
NC
CTL5
CTL4
C113
C7
R13
GND
P2
PA2_IN
VDD_RF_B AT
GND
GND
ANT2
GND
ANT1
GND
PA_VCC2
PA_VCC1
GND
1
2
3
4
5
6
7
8
9
10
HDR_1X10
C16
P1-3
C23
L2
C6
C112
C66
C2
PA_VCC2
C42
L3
C20
C19
L5
C111
C65
C115
C27
L1
ANT2
C30
NC
ATB4
R8
C34
C62
XTL
P4
P5
C35
1
2
3
1
2
3
CTL5
ADF7023
R9
CTL2
VDD_RF_BA T
VCOGUA RD
C33
VDD_BAT
RFO 2
RFIO_1N
RFIO_ 1P
VDD _RF2
RBIAS
PA_VCC1
C14
ADC IN_ATB3
VDD_SYNTH
L4
R12
C15
VDDBAT1
CSYNTH
C26
PA1_OUT
OSC 32KN_ATB2
XOS C26P
C24
PA1_IN
LN A_VCC
1
2
3
4
5
6
7
8
9
10
HDR_1X10
GND
LNA_BIAS
Rev. A | Page 5 of 8
LN A_IN
Figure 2. Schematic
ASW_RX
OSC KP_G P5_ATB1
XOS C26N
ADCVREF
VDD_VCO
VDDIG
DGUARD
C37
R15
R16
CTL4
CTL3
PA_VCC2
R3
VDD_RF_B AT
C2
PA_VCC1
GP 0
GP 1
GP 2
IRQ_GP 3
MISO
SCLK
MOSI
CSN
GP 4
VDDIG
VDD_RF1
GND
P2
C1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
HDR_1X20
P3
Application Note
AN-1309
REFERENCE DESIGN SCHEMATICS AND ARTWORK
A full reference design package is available from the Analog Devices website that consists of Gerber files, circuit schematic, fabrication
notes, and the bill of materials (BOM).
12322-002
AN-1309
Application Note
RECOMMENDED PCB LAYOUT
12322-003
Figure 3 and Figure 4 show the recommended PCB layout. The Gerber files are available from the Analog Devices website.
12322-004
Figure 3. PCB Layout Diagram
Figure 4. Component Placement Diagram
Rev. A | Page 6 of 8
Application Note
AN-1309
BILL OF MATERIALS
Table 4. Components Listing
Name
Value
Tolerance
PCB Decal
SMD
Layer
Manufacturer
Part Number
C1
C2
C4
C6
C7
C8
C10
C11
C12
C15
C16
C18
C19
C20
C23
C24
C26
C27
C28
C30
C33
C34
C35
C37
C42
C62
C65
C66
C111
C112
C113
C115
J2
L1
L2
L3
L4
L5
P1
P2
P3
P4
P5
R1
R3
R4
DNI
3.3 pF
0.1 µF
1 nF
1 nF
1 nF
1 nF
1 nF
1 nF
100 pF
220 nF
56 pF
2.7 pF
1.2 pF
220 nF
220 nF
10 µF
100 pF
220 nF
220 nF
220 nF
18 pF
18 pF
220 nF
10 µF
150 nF
220 nF
100 pF
0.1 µF
0.1 µF
0.1 µF
1 nF
N/A
N/A
±5%
±10%
±10%
±10%
±10%
±10%
±10%
±5%
±10%
±5%
±0.25
±0.25
±10%
±10%
±20%
±5%
±10%
±10%
±10%
±5%
±5%
±10%
±20%
±10%
±10%
±5%
±5%
±5%
±5%
±10%
47 nH
7.5 nH
12 nH
6.2 nH
7.5 nH
±5%
±5%
±5%
±5%
±5%
DNI
DNI
DNI
±1%
±1%
±1%
C0402
C0402
C0402
C0201
C0201
C0201
C0201
C0201
C0201
C0402
C0402
C0402
C0402
C0402
C0402
C0402
C0603
C0402
C0402
C0402
C0402
C0402
C0402
C0402
C0603
C0402
C0402
C0402
C0402
C0402
C0402
C0201
SMA_CARD_EDGE_RF
L0402
L0402
L0402
L0402
L0402
SKT10_1.27MM
SKT10_1.27MM
SKT20_1.27MM
SIP-3P-RA_SMD
SIP-3P-RA_SMD
R0201
R0402
R0402
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
Yes
Yes
Yes
Yes
Yes
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Bottom
Top
Top
Top
Top
Top
Top
Top
Bottom
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Bottom
Bottom
Bottom
Top
Top
Top
Top
Top
N/A
Murata
Murata
TDK
TDK
TDK
TDK
TDK
TDK
Murata
Murata Electronics
Murata
Murata
Murata
Murata Electronics
Murata Electronics
Johanson
Murata
Murata Electronics
Murata Electronics
Murata Electronics
Murata
Murata
Murata Electronics
Johanson
Murata Electronics
Murata Electronics
Murata
Murata
Murata
Murata
TDK
Johnson Components
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Samtec
Samtec
Samtec
Sullins
Sullins
N/A
N/A
N/A
N/A
GRM1555C1H3R3CA01D
GRM155R71C104KA88D
C0603X7R1E102K030BA
C0603X7R1E102K030BA
C0603X7R1E102K030BA
C0603X7R1E102K030BA
C0603X7R1E102K030BA
C0603X7R1E102K030BA
GRM1555C1H101JZ01D
GRM155R61A224KE19D
GRM1555C1H560JD01D
GRM1555C1H2R7CZ01D
GRM1555C1H1R2CZ01D
GRM155R61A224KE19D
GRM155R61A224KE19D
6R3R14X106MV4T
GRM1555C1H101JZ01D
GRM155R61A224KE19D
GRM155R61A224KE19D
GRM155R61A224KE19D
GRM1555C1H180JZ01D
GRM1555C1H180JZ01D
GRM155R61A224KE19D
6R3R14X106MV4T
GRM155R61A154KE9D
GRM155R61A224KE19D
GRM1555C1H101JZ01D
GRM155R71C104KA88D
GRM155R71C104KA88D
GRM155R71C104KA88D
C0603X7R1E102K030BA
142-0711-821
0402CS-47NXJL
0402CS-7N5XJL
Coilcraft 0402CS-12NXJL
Coilcraft 0402CS-6N2XJL
Coilcraft 0402CS-7N5XJL
SFM-105-02-S-D-A
SFM-105-02-S-D-A
SFM-110-02-S-D-A
GEC36SGSN-M89
GEC36SGSN-M89
N/A
N/A
N/A
Rev. A | Page 7 of 8
AN-1309
Application Note
Name
Value
Tolerance
PCB Decal
SMD
Layer
Manufacturer
Part Number
R5
R8
R9
R12
R13
R15
R16
U1
U2
Y1
0r
0r
0r
36 k
DNI
100 k
0r
±1%
±1%
±1%
±1%
N/A
±1%
±1%
R0402
R0402
R0402
R0402
R0402
R0402
R0402
LFCSP-32
LGA, 32-Pin, 6 mm × 6 mm
XTAL-SMD-3_2-2_5MM
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Top
Top
Top
Top
Top
Top
Top
Top
Yes
Top
Rohm
Rohm
Rohm
Rohm
N/A
Rohm
Rohm
Analog Devices
RFMD
NDK
MCR01MRTJ000
MCR01MRTJ000
MCR01MRTJ000
MCR01MZPF3602
N/A
MCR01MZPF1003
MCR01MRTJ000
ADF7023-LFCSP32
RFFM6901
NX3225SA-26.000000MHZ-G2
26 MHz
©2014 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
AN12322-0-5/14(A)
Rev. A | Page 8 of 8