Table of Contents
Advertisement
7. Radio
7.1 Overview
The LR1121 is a half-duplex RF transceiver capable of handling constant envelope modulation schemes such as LoRa,
(G)FSK, and LR-FHSS. The LoRa and (G)FSK modulations are fully compatible with the SX1261/62/68 family for sub-GHz, and
can be configured to be compatible with the SX1280/81 family for 2.4GHz.
The radio system is shown in
three TX paths ( High Power, Low Power and High Frequency), and two RX paths, 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, and the LR-FHSS modulator.
The PAs are described in a dedicated section, as well as the LoRa and (G)FSK modems, and the LR-FHSS modulation.
Balun
RFIO_HF
&
Match
RFI_N_LF0
RFI_P_LF0
RFO_LP_LF
RFO_HP_LF
VBAT_RF
VR_PA
The LR1121 frequency synthesizer allows a continuous operation in the 150MHz-2500MHz frequency range. It is shared
between the sub-GHz radio and HF radio, therefore no simultaneous sub-GHz /HF radio operation is possible.
The LR1121 frequency synthesizer is clocked by a 32MHz reference, provided by either a crystal oscillator, or a TCXO. Refer
to
Section 6. "Clock Sources" on page 44
LR1121
User Manual
Rev 1.1
UM.LR1121.W.APP
Mar 2023
Figure 7-1: Radio
below. It is composed of the frequency synthesizer (also referred as PLL),
PA
HF
LNA
HF
ADC
ADC
LNA
LF0
PA
LP LF
PLL
PA
HP LF
PDS
DC-DC
REG_PA
REGs
REGs
LDO
Figure 7-1: Radio
for details.
www.semtech.com
LoRa
LoRa
(G)FSK
(G)FSK
modem
modem
modem
modem
BG/IREF
HFXOSC
HFRC
POR/
32MHz
32MHz
BRN
NVM
CPU
ROM
RAM
CKS
LFXOSC
LFRC
32kHz
32kHz
Proprietary & Confidential
DIO0/ BUSY
DIO1
DIO2
DIO3
DIO4
DIO5
DIO6
DIO7
DIO8
DIO9
nRESET
48 of 130
Semtech
Advertisement
Table of Contents
