TDA5220 Datasheet, PDF (27/44 Pages) Infineon Technologies AG – ASK/FSK Single Conversion Receiver

confidential
TDA 5220
preliminary
Applications
4.5 Data Slicer Threshold Generation
The threshold of the data slicer can be generated using an external R-C inte-
grator as shown in Figure 4-5. The cut-off frequency of the R-C integrator has
to be lower than the lowest frequency appearing in the data signal. In order to
keep distortion low, the minimum value for R is 20kΩ.
R
C
Pins: 19
data
filter
20
U_threshold
data out
25
CM
data slicer
Figure 4-5
Data_slice1.wmf
Data Slicer Threshold Generation with External R-C Integrator
In case of ASK operation another possibility for threshold generation is to use
the peak detector in connection with an internal resistive divider and one capac-
itor as shown in the following figure. The component values are depending on
the coding scheme and the protocol used.
data
filter
C
Pins: ₂₆
peak detector
56k
data out
25
390k
data slicer
U_threshold
CP
Figure 4-6
Data_slice2.wmf
Data Slicer Threshold Generation Utilising the Peak Detector
Wireless Components
4-7
Target Specification, October 2001