tda5255e1 Infineon Technologies Corporation, tda5255e1 Datasheet - Page 73

• Manufacturer Part Number: tda5255e1
• Description: Ask/fsk 434mhz Wireless Transceiver
• Manufacturer: Infineon Technologies Corporation

TDA5255 E1
Version 1.1
Application
Confidential
The best sensitivity performance can be achieved using a data filter bandwidth of 1.25 times the
maximum occuring data frequency.
The IQ filter setting is depending on the modulation type. ASK needs an IQ filter of 50kHz, 50kHz
deviation at FSK recommend a 100kHz IQ filter and 100kHz deviation were measured with a
150kHz IQ filter
A very practicable configuration is to set the chip-internal adjustable IQ filter to the sum of FSK peak
deviation and maximum datafrequency. Concerning these aspects the bandwidth should be chosen
small enough. With respect to both, the crystal tolerances and the tolerances of the crystal oscillator
circuit of receiver and transmitter as well, a too small IQ filter bandwidth will reduce the sensitivity
again. So a compromise has to be made. For further details on chip tolerances see also Section
3.2.7
3.10.2
BER performance depending on Supply Voltage
Due to the wide supply voltage range of this transeiver chip also the sensitivity behaviour over this
parameter is documented is the subsequent graph.
BER_VCC.wmf
Figure 3-37
BER supply voltage
Please notice the tiny sensitivity changes of 1.0 to 1.5dB, when variing the supply voltage.
Preliminary Specification
73
2002-11-28