LR1110
User Manual
Rev.1.0
UM.LR1110.W.APP
March 2020
41 of 130
Semtech
7. Sub GHz Radio
7.1 Description
The LR1110 is a half-duplex RF transceiver capable of handling constant envelope modulation schemes such as LoRa®, and
(G)FSK. It is fully compatible with the SX1261/62/68 family.
The sub-GHz radio system is shown in figure
here below. It is composed of the frequency
synthesizer (also referred as PLL), two TX paths (High Power and Low Power), and a RX path, followed by a high-bandwidth
ADC. Both the ADC and the PLL are tied to the digital subsystem and to the LoRa® and (G)FSK modems.
The High Power and the Low Power PA are described in a dedicated section, as well as the LoRa® and (G)FSK modems.
Figure 7-1: Sub-GHz Radio
The LR1110 frequency synthesizer allows a continuous operation in the 150 MHz-2700 MHz frequency range. It is shared
between the sub-GHz radio, the GNSS and the Wi-Fi scanning engines, therefore no simultaneous sub-GHz radio operation,
GNSS scanning, or Wi-Fi scanning is possible.
The LR1110 frequency synthesizer is clocked by a 32 MHz reference, provided by either a crystal oscillator, or a TCXO. Refer
to
Section 6. "Clock Sources" on page 38
for details.
LNA
LF0
LNA
LF1
PA
HP LF
PA
LP LF
RFO_HP_LF
RFO_LP_LF
RFI_P_LF0
RFI_N_LF0
RFI_P_LF1
RFI_N_LF1
LNA
HF
Balun
&
Match
RFIO_HF
ADC
PLL
VBAT_RF
VR_PA
VR
EG
DC
C
_
S
W
VB
A
T
VB
A
T_
R
F
DC-DC
LDO
BG/IREF
POR/
BRN
PDS
REGs
HFXOSC
32MHz
CKS
LFXOSC
32kHz
HFRC
32MHz
LFRC
32kHz
XT
A
XT
B
DIO11/
32
k
_
P
DIO10/
32k
_
N
VTCX
O
DIO0/ BUSY
DIO1
DIO2
DIO3
DIO4
DIO9
DIO8
DIO7
DIO6
DIO5
150 –
960 M
H
z,
TX
150 –
960 M
H
z,
RX
2.
412 –
2.
484 G
H
z,
RX
REG_PA
Di
gi
ta
l Ba
se
ba
n
d
+ D
S
P
CPU
RAM
ROM
NVM
IO
SW
M
Di
gi
ta
l Fr
o
n
t-
E
n
d
LoRa
modem
(G)FSK
modem
NRESET
1.
5 –
1.
6 G
H
z,
RX
