WIRELES S SENSING TIMING PRO ODUCTS Sx127x R Reference D AN12 Design Over 20019 rview AP PLICATION N NOTE SX1 127x Refer rence vervie gn Ov Desig 19 ew 2001 AN12 Revision 1 2014 Se 1 May 2014 emtech Corpo oration www semtechcom m P a g e 1 WIRELES S SENSING TIMING PRO ODUCTS Sx127x R Reference D AN12 Design Over 20019 rview ......
200.19
AN12
WIRELES
S, SENSING &
& TIMING PRO
ODUCTS
Sx127x R
Reference D
Design Over
rview
AP
PLICATION N
NOTE
AN12 19
200.1
SX1
127x Refer
rence Desig vervie
gn Ov
ew
1, May 2014
Revision 1
@2014 Se
emtech Corpo
oration
m
www.semtech.com
P a g e
| 1
200.19
AN12
WIRELES
S, SENSING &
& TIMING PRO
ODUCTS
Sx127x R
Reference D
Design Over
rview
AP
PLICATION N
NOTE
roduction
n
1 Intr
This purpo
ose of this do
ocument is to
assist the en
ngineer with b
both the selec
ction of the o
optimum refe
erence
design mo
odule and the
e associated development
t tool for the
e SX127x family of LoRa™
long‐range,
ultra‐
tenna
low powe transceivers, and provi
er
iding informa
ation relating to circuit o
g
optimization f single ant
for
port OEM
M designs.
It is recom
mmended tha
at this applica
ation note is r
read in conjun
nction with th
he following d
documents:
1.
2.
3.
4.
5.
6.
7.
SX
X1272 Datash
heet
SX
X1276 Datash
heet
SX
X1272 Docum
ment and Reso
ources Design
n Pack:
SX
X1276 Docum
ment and Reso
ources Design
n Pack:
SX
X1232 Datash
heet:
SX
X1232 Docum
mentation and
d Resources D
Design Pack:
Se
emtech Appli
ication Note A
AN1200.6, “SX1232 LNA an
nd PA Impeda
ance Matchin
ng Techniques”
LoRa™
™ Modulat
tion
LoRa™, Semtech’s pro
S
oprietary mo
odulation is a spread‐spec
a
ctrum techniq that use wideband linear
que
es
frequency modulated pulses to en
y
ncode inform
mation, whose frequency increases or decreases o
e
over a
certain am
mount of time
e.
As with other spread‐
o
‐spectrum
mo
odulation tec
chniques LoR
Ra™ uses the entire chan
e
nnel bandwid to
dth
broadcast
t a signal, making it robust
t to channel n
noise. In addit
tion, because
e LoRa modulation uses a broad
band of the spectrum
it is also res
t
sistant to lon term relat ive frequency error, mult
ng
ti‐path, fading and
y
Doppler e
effects.
1, May 2014
Revision 1
@2014 Se
emtech Corpo
oration
m
www.semtech.com
P a g e
| 2
200.19
AN12
WIRELES
S, SENSING &
& TIMING PRO
ODUCTS
Sx127x R
Reference D
Design Over
rview
AP
PLICATION N
NOTE
2 Sem
mtech LoR
Ra Module
e Referen
nce Design
ns
2.1 SX
X1272
The SX12
272RF1xAS re
eference des
sign module schematic is illustrated below in Fig
s
gure 1. From the
m
schematic
c it can be ob
bserved that the split RX/T
TX path as re
eferenced in t
the specificat
tion section o
of the
datasheet
t [1] has been
n employed.
Figure 1: SX127
72RF1 Evaluatio
on Module
The split path approa allows fo the receive RFI port t be optimized for sens
ach
or
er
to
sitivity rather than
r
g
ned
ciency transm
mitter RFO / RFI lumped‐
‐element
matching single path
e
employing the combin high‐effic
network o
of the SX1232
2. The high‐po
ower PA Boos
st transmitter
r port is empl
his design, ena
abling
loyed with th
transmitte
ed output po
ower up to +2
20 dBm. Note
e that the hig
gh‐efficiency RFO port is le
eft open‐circuit on
this design implementa
ation.
Port combination to a single anten port is achieved via t single control line RF switch. Whil the
a
nna
the
le
reference
e module is in
ntended to in
nterface with
the appropr
riate Semtech
h SX127x Dev
velopment Ki
it and
thus the s
switch contro
ol line is via a separate con
ntrol port, by
y open‐circuiting R2 and pl
lacing a 1k re
esistor
at R1, the
e RF switch may be control
lled via the RX
XTX pin of the
e SX1272 (Pin
n 23.)
1, May 2014
Revision 1
@2014 Se
emtech Corpo
oration
m
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P a g e
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200.19
AN12
WIRELES
S, SENSING &
& TIMING PRO
ODUCTS
Sx127x R
Reference D
Design Over
rview
AP
PLICATION N
NOTE
2.2 SX
X1276
There are
e three versions of the SX1276 reference design mod
dule and thes
se are summa
arized below:
1. SX
X1276RF1IAS: 169 MHz / 8
868 – 915 MH
Hz
2. SX
X1276RF1JAS
S: 433 MHz / 8
868 – 915 MH
Hz
3. SX
X1276RF1KAS
S: 470 – 490 M
MHz / 868 – 9
915 MHz
All SX127
76RF1xAS ref
ference modu designs employ the split RX / TX path architecture to e
ule
e
X
ensure
optimum performance
e of both the transmitter a
and receiver [
[2].
2.2.1 SX
X1276RF1IA
AS
chematic is il
The SX127
76RF1IAS 169
9 MHz / 868 –
– 915 MHz re
eference desiign module sc
llustrated bel
low in
Figure 2.
Figu
ure 2: SX1276RF
F1IAS 169 MHz /
/ 868 – 915 MHz
z Dual‐Band Ref
ference Design
–
b
igured using RFI_HF and RFO_HF, wh the 169 MHz band utilizes
hile
The 868 – 915 MHz band is confi
PA_Boost
t and RFI_LF. Note that the
e RFO_LF pin is not connec
cted.
1, May 2014
Revision 1
@2014 Se
emtech Corpo
oration
m
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P a g e
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200.19
AN12
WIRELES
S, SENSING &
& TIMING PRO
ODUCTS
AP
PLICATION N
NOTE
This refer
rence design configuratio is primaril targeted f ETSI / EU applications The high‐p
on
ly
for
U
s.
power
transmitte
er PA_Boost is optimized for the 169 M
MHz band to
take advant
age of the 50
00 mW ERP p
power
limit available in this b
band. RFO_HF is optimize
ed for 868 M Hz – 915 MH
Hz. The +14 d
dBm output p
power
s suitable for the 25 mW E
ERP permitted
d in the majo
ority of the Eu
uropean 863 – 870
available at this port is
d as well as th
he proposed g
g2, g2.1, g3 and g3.1 ban
nd extensions
s (870 – 876 M
MHz and 915 – 921
MHz band
MHz)
2.2.2 SX
X1276RF1JA
AS
The SX127
76RF1JAS 433
3 MHz / 868 –
– 915 MHz re
eference desiign module sc
chematic is il
llustrated bel
low in
Figure 3:
Sx127x R
Reference D
Design Over
rview
Figu
ure 3: SX1276RF
F1JAS 433 MHz /
/ 868 – 915 MHz
z Dual‐Band Ref
ference Design
The 433 M
MHz band is c
configured with RFI_LF and RFI_LF. The
e high‐efficien
ncy transmitt
ter is ideally s
suited
to meet the maximum
m ERP limits p
prescribed by both ETSI an
nd the FCC, even when an
ntenna efficie
ency is
reduced d
due to size co
onstraints.
The 868 / 915 MHz band is config
/
b
gured with PA_Boost and RFI_HF. No that the RFO_LF pin i not
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