TDA5150 Datasheet, PDF (8/106 Pages) Infineon Technologies AG – On-chip, high resolution fractional-N synthesizer and Sigma-Delta modulator with ASK, FSK, GFSK options

TDA 5150
Product Description
The matching shown is an example for a loop antenna application. Different antenna
types (electrical monopole or dipole, magnetic loop etc.) as well as different layout
versions might require component values which can differ from those given in above
example. The antenna geometry has a major influence on the antenna impedance and
consequently on the component values in the matching network.
1.5.2 Sigma-Delta fractional-N PLL with High Resolution
This type of PLL offers a multitude of advantages compared to fixed, integer division ratio
PLLs.
In the reference oscillator circuit the same crystal can be used for all of the RF bands
and frequencies (for example a 13 MHz crystal).
Dedicated crystals for each frequency are no longer required.
However by choice of crystal frequency a phenomenon, known as occurrence of
fractional-N spurs must be kept in mind. The phenomenon and the countermeasures
which should be taken to avoid it are described in detail in Chapter 2.4.6.1.
The PLL allows a direct (G)FSK modulation for reduced spurs and harmonics with high
accuracy and resolution compared to legacy transmitters using crystal pulling for FSK
modulation.
Synthesizer resolution down to 7 Hz for carrier frequency and FSK deviation allows fine
tuning, correction of crystal tolerances and for temperature drift.
Data Sheet
8
V 1.0, July 2009