RFM92 Datasheet, PDF (21/126 Pages) List of Unclassifed Manufacturers – Low Power Long Range Transceiver Module

RFM92W/93W V3.0
3. RFM92W/93W Features
This section gives a high-level overview of the functionality of the RFM92W/93W low-power, highly integrated transceiver.
The following figure shows a simplified block diagram of the RFM92W/93W.
Figure 4. Simplified RFM92W Block Schematic Diagram
RFM92W/93W Is a half-duplex, low-IF transceiver. Here the received RF signal is first amplified by the LNA. The LNA
input is single ended to minimize the external BoM and for ease of design. Following the LNA output, 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).
The frequency synthesizer generates the local oscillator (LO) frequency for both receiver and transmitter. The PLL is
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 prefiltering of the bit stream to improve
spectral purity.
RFM92W/93W feature a pair of RF power amplifiers. The first, connected to RFO, can deliver up to +14 dBm, is
unregulated for high power efficiency and can be connected directly to the RF receiver input via a pair of passive
components to form a single antenna port high efficiency transceiver. The second PA, connected to the PA_BOOST pin
and can deliver up to
+20 dBm via a dedicated matching network.
RFM92W/93W also include two timing references, an RC oscillator and a 32 MHz crystal
oscillator.
All major parameters of the RF front end and digital state machine are fully configurable via an SPI interface which gives
access to RFM92W/93W’s configuration registers. This includes a mode auto sequencer that oversees the transition and
calibration of the RFM92W/93W between intermediate modes of operation in the fastest time possible.
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