SX1276IMLTRT View Datasheet(PDF) - Semtech Corporation
Part Name
Description
Manufacturer
SX1276IMLTRT Datasheet PDF : 132 Pages
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SX1276/77/78/79
WIRELESS, SENSING & TIMING
DATASHEET
3. SX1276/77/78/79 Features
This section gives a high-level overview of the functionality of the SX1276/77/78/79 low-power, highly integrated
transceiver. The following figure shows a simplified block diagram of the SX1276/77/78/79.
Figure 4. SX1276/77/78/79 Block Schematic Diagram
SX1276/77/78/79 is a half-duplex, low-IF transceiver. Here the received RF signal is first amplified by the LNA. The LNA
inputs are single ended to minimize the external BoM and for ease of design. Following the LNA inputs, the conversion to
differential is made to improve the second order linearity and harmonic rejection. The signal is then down-converted to in-
phase and quadrature (I&Q) components at the intermediate frequency (IF) by the mixer stage. A pair of sigma delta ADCs
then perform data conversion, with all subsequent signal processing and demodulation performed in the digital domain.
The digital state machine also controls the automatic frequency correction (AFC), received signal strength indicator (RSSI)
and automatic gain control (AGC). It also features the higher-level packet and protocol level functionality of the top level
sequencer (TLS), only available with traditional FSK and OOK modulation schemes.
The frequency synthesizers generate the local oscillator (LO) frequency for both receiver and transmitter, one covering the
lower UHF bands (up to 525 MHz), and the other one covering the upper UHF bands (from 779 MHz). The PLLs are
optimized for user-transparent low lock time and fast auto-calibrating operation. In transmission, frequency modulation is
performed digitally within the PLL bandwidth. The PLL also features optional pre-filtering of the bit stream to improve
spectral purity.
SX1276/77/78/79 feature three distinct RF power amplifiers. Two of those, connected to RFO_LF and RFO_HF, can deliver
up to +14 dBm, are unregulated for high power efficiency and can be connected directly to their respective RF receiver
inputs via a pair of passive components to form a single antenna port high efficiency transceiver. The third PA, connected to
the PA_BOOST pin and can deliver up to +20 dBm via a dedicated matching network. Unlike the high efficiency PAs, this
high-stability PA covers all frequency bands that the frequency synthesizer addresses.
SX1276/77/78/79 also include two timing references, an RC oscillator and a 32 MHz crystal oscillator.
Rev. 4 - March 2015
©2015 Semtech Corporation
Page 23
www.semtech.com
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