SX1232
WIRELESS & SENSING
DATASHEET
3.4.4. OOK Modulation
OOK modulation is applied by switching on and off the Power Amplifier. Digital control and smoothing are available to
improve the transient power response of the OOK transmitter.
3.4.5. Modulation Shaping
Modulation shaping can be applied in both OOK and FSK modulation modes, to improve the narrowband response of the
transmitter. Both shaping features are controlled with PaRamp bits in RegPaRamp.
In FSK mode, a Gaussian filter with BT = 0.5 or 1 is used to filter the modulation stream, at the input of the sigma-delta
modulator. If the Gaussian filter is enabled when the SX1232 is in Continuous mode, DCLK signal on pin 10 (DIO1/
DCLK) will trigger an interrupt on the uC each time a new bit has to be transmitted. Please refer to section 5.4.2 for
details.
When OOK modulation is used, the PA bias voltages are ramped up and down smoothly when the PA is turned on and
off, to reduce spectral splatter.
Note the transmitter must be restarted if the ModulationShaping setting is changed, in order to recalibrate the built-in
filter.
3.4.6. RF Power Amplifiers
Three power amplifier blocks are embedded in the SX1232. The first one herein referred to as PA0, can generate high
efficiency RF power into a 50 ohm load. The RF power is programmable between -1dBm and +14dBm. PA0 is connected
to pin RFO (pin 22).
PA1 and PA2 are both connected to pin PA_BOOST (pin 23). They can deliver up to +17 dBm in programmable step of 1dB
to the antenna, a specific impedance matching / harmonic filtering design is required to ensure impedance transformation
and regulatory compliance. The RF power is programmable between +2 dBm and +17 dBm. The high power mode allows
to achieve fixed output power of +20dBm.
Table 10 Power Amplifier Mode Selection Truth Table
PaSelect
Mode
PA0 output on pin RFO
Power Range
Pout Formula
-1 to +14 dBm
-1 dBm + OutputPower
0
1
1
PA1 and PA2 combined on pin PA_BOOST
+2 to +17 dBm
+5 to +20 dBm
+2 dBm + OutputPower
+5 dBm + OutputPower
PA1+PA2 on PA_BOOST with high output
power +20dBm settings (see 3.4.7)
Notes - For +20dBm restrictions of operation, please consult the following section
- To ensure correct operation at the highest power levels, please make sure to adjust the OcpTrim accordingly in
RegOcp.
- If PA_BOOST pin is not used the pin can be left floating.
Rev 3 - August 2012
Page 24
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