RM0453 Rev 5 157/1450
RM0453 Sub-GHz radio (SUBGHZ)
227
5.3.3 Transmitter
The transmit chain comprises the modulated output from the modem, that directly
modulates the RF-PLL. An optional pre-filtering of the bit stream can be enabled to reduce
the power in the adjacent channel also dependent on the selected modulation scheme. The
modulated signal from the RF-PLL directly drives the high-power PA (HP PA) or low-power
PA (LP PA).
Transmitter high output power
Transmit high output power up to + 22 dBm, is supported through the RFO_HP RF pin. The
HP PA can be supplied from the PA regulator (REG PA) up to 3.1 V.
For this, the REG PA must be supplied directly from V
DD
(on VDDSMPS pin), as shown in
Figure 10.
Figure 10. High output power PA
HSERDY Digital output HSE32 clock ready indication
SUBGHZSPI Digital in/output Sub-GHz radio SPI interface
BUSY Digital output BUSY signal
Interrupts Digital output IRQ interrupts
Table 26. Sub-GHz internal input/output signals (continued)
Signal name Signal type Description
MSv62616V2
VLXSMPS
VFBSMPS (1.55V)
VDDPA
VR_PA (up to 3.1V)
RFO_HP
LDO/SMPS
REG
PA
HP PA
VLXSMPS
VFBSMPS (1.55V)
VDDPA
VR_PA (up to 3.1V)
RFO_HP
LDO/SMPS
REG
PA
HP PA
V
DD
V
DD
V
DD
V
DD
VDDSMPS (1.8 to 3.6V) VDDSMPS (1.8 to 3.6V)
LDO mode
SMPS mode
Note: Use of the SMPS is optional. When SMPS is not used, the BOM can be reduced by removing the coil
between VLXSMPS and VFBSMPS pins.
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