Data Sheet

LJ1269HC
Rev1.0 Page 20 Web: www.ljelect.com
3.3.5. 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 = 0.3, 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 LJ1269HC is in Continuous mode, DCLK signal on pin 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 PaRamp setting is changed, in order to recalibrate the built-in filter.
3.3.6. Power Amplifiers
A higher power mode, when PA1 and PA2 are combined, providing up to +20 dBm to a matched load.
W hen PA1 and PA2 are combined to deliver +20 dBm to the antenna, a specific impedance matching / harmonic filtering design
is required to ensure impedance transformation and regulatory compliance.
All PA settings are controlled by RegPaLevel, and the truth table of settings is given in Table 10.
Table 10 Power Amplifier Mode Selection Truth Table
Pa0On
Pa1On
Pa2On
Mode
Power Range
Pout Formula
1
0
0
PA0 output on pin RFIO
-18 to +13 dBm
-18 dBm + OutputPower
0
1
0
PA1 enabled on pin PA_BOOST
-2 to +13 dBm
-18 dBm + OutputPower
0
1
1
PA1 and PA2 combined on pin PA_BOOST
+2 to +17 dBm
-14 dBm + OutputPower
0
1
1
PA1+PA2 on PA_BOOST with high output
power +20dBm settings (see 3.3.7)
+5 to +20 dBm
-11 dBm + OutputPower
Other combinations
Reserved
Notes To ensure correct operation at the highest power levels, please make sure to adjust the Over Current Protection Limit
accordingly inRegOcp, except above +18dBm where it must be disabled
If PA_BOOST pin is not used (+20dBm applications and less), the pin can be left floating.
Sub GHz FSK/OOK Transceiver Module DATASHEET