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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
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.
Balun
&
RFIO_HF
Match
RFI_N_LF1
RFI_P_LF1
RFI_N_LF0
RFI_P_LF0
RFO_LP_LF
RFO_HP_LF
VBAT_RF
VR_PA
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
LR1110
User Manual
Rev.1.0
UM.LR1110.W.APP
March 2020
Figure 7-1: Sub-GHz Radio
LNA
HF
ADC
LNA
LF1
LNA
LF0
PA
LP LF
PLL
PA
HP LF
PDS
DC-DC
REG_PA
REGs
LDO
Figure 7-1: Sub-GHz Radio
for details.
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here below. It is composed of the frequency
LoRa
(G)FSK
modem
modem
BG/IREF
HFXOSC
HFRC
POR/
32MHz
32MHz
BRN
NVM
CPU
ROM
RAM
CKS
LFXOSC
LFRC
32kHz
32kHz
NRESET
DIO0/ BUSY
DIO1
DIO2
DIO3
DIO4
DIO5
DIO6
DIO7
DIO8
DIO9
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