TDA5150 Datasheet, PDF (48/106 Pages) Infineon Technologies AG – On-chip, high resolution fractional-N synthesizer and Sigma-Delta modulator with ASK, FSK, GFSK options

TDA 5150
TDA 5150 Functional Description
The Duty Cycle Control is accessible through the bits DCCCONF (0x1F.5:4) of SFR
ANTTDCC (0x1F).See Chapter DCCCONF for details.
In the 315 MHz band the DCCCONF and DCCDISABLE bits are ignored and the
optimized (and predefined) value of 33% Duty Cycle is superimposed
2.4.8.4 Antenna Tuning
A block of 4 switchable capacitors is paralleled with the PA output. The Antenna Tuning
option can be useful for fine-tuning the PA to Load matching network, and thus to obtain
a better antenna performance in a wider frequency band. This feature is useful by
multichannel applications, for maintaining antenna matching close to the optimum. The
tuning capacitors can be switched ON / OFF individually and the control of the switches
is implemented in SFR TUNETOP (0x1F).
.
VBAT
TUNETOP
TDA 5150
PA _IN
PA
PA
Ant
Tune
Ctrl
switched caps
0.06~0.9pF
Antenna
C1
(incl. parasitic from
PA)
Choke
C2
Figure 18 PA Antenna Tuning and Matching
The 4 switched capacitors have different values of typically 60 fF, 120 fF, 240 fF and 480
fF, giving an overall maximum capacitance of about 0.9 pF.
Note: Due to the low Q Factor of the switched capacitors at the higher frequencies, the
device´s current consumption tends to increase when this feature is used in the
868 MHz and 915 MHz frequency bands.
Data Sheet
48
V 1.0, July 2009