RFM92 Datasheet, PDF (82/126 Pages) List of Unclassifed Manufacturers – Low Power Long Range Transceiver Module

RFM92W/93W V3.0
5.4. Transmitter Description
The transmitter of RFM92W/93W comprises the frequency synthesizer, modulator (both LoRa^TM and FSK/OOK) and
power amplifier blocks, together with the DC biasing and ramping functionality that is provided through the VR_PA block.
5.4.1. Architecture Description
The architecture of the RF front end is shown in the following diagram. Here we see that the unregulated PA0 is connected
to the RFO pin features a single low power amplifier device. The PA_BOOST pin is connected to the internally regulated
PA1 and PA2 circuits. Here PA2 is a high power amplifier that permits continuous operation up to +17 dBm and duty cycled
operation up to +20 dBm. For full details of operation at +20 dBm please consult Section 5.4.3.
LNA
RF I
Re c eiv er Ch ain
RFO
PA 0
PA 1
Loc al
Os c illa tor
PA _BOOS T
PA 2
Figure 41. RF Front-end Architecture Shows the Internal PA Configuration.
5.4.2. RF Power Amplifiers
Three power amplifier blocks, PA0 - PA2, are available in the RFM92W/93W. PA0 is a high efficiency amplifier capable of
yielding RF power programmable in 1 dB steps from -1 dBm to +14 dBm directly into a 50 ohm load with low current
consumption. PA0 is connected to pin RFO (pin 24).
PA1 and PA2 are both connected to pin PA_BOOST (pin 27). There are two potential configurations of these power
amplifiers, fixed or programmable. In the fixed configuration they can deliver up to +20 dBm. In programmable
configuration they can provide from +17 dBm to +2 dBm in 1 dB programmable steps. Naturally, low impedance matching
and harmonic filtering is required to ensure RF power delivery and regulatory compliance. (See the applications Section of
this document for more details).
Table 31 Power Amplifier Mode Selection Truth Table
PaSelect
0
1
1
Mode
PA0 output on pin RFO
PA1 and PA2 combined on pin PA_-
BOOST
PA1+PA2 on PA_BOOST with high output
power +20 dBm settings (see 5.4.3)
Power Range
-1 to +14 dBm
+2 to +17 dBm
+5 to +20 dBm
Pout Formula
-1 dBm + OutputPower
+2 dBm + OutputPower
+5 dBm + OutputPower
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