TDA5212_06 Datasheet, PDF (28/49 Pages) Infineon Technologies AG – ASK/FSK 915MHz Single Conversion Receiver

TDA 5212
Applications
4.5 Data Slicer Threshold Generation
The threshold of the data slicer can be generated in two ways, depending on
the signal coding scheme used. In case of a signal coding scheme without DC
content such as Manchester coding the threshold can be generated using an
external R-C integrator as shown in Figure 4-5. The time constant T_A of the R-
C integrator has to be significantly larger than the longest period of no signal
change T_L within the data sequence. For the calculation of the time constant T_A
please see Application Note „TDA521X_ANV1.1.“ chapter „4.11. Data Slicer“.
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
data slicer
Figure 4-5
Data_slice1.wmf
Data Slicer Threshold Generation with External R-C Integrator
Another possibility for threshold generation is to use the peak detector in con-
nection with two resistors and one capacitor as shown in the following figure.
The component values are depending on the coding scheme and the protocol
used.
R
C
R
Pins: ₂₆ 19
peak detector
20
U_threshold
data out
25
data slicer
data
filter
Figure 4-6
Data_slice2.wmf
Data Slicer Threshold Generation Utilising the Peak Detector
Wireless Components
4-7
Specification, December 2006