User Manual
718
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
Measurement Core Module (incl. ADC2)
23.6
IIR-Filter
23.6.1
Functional Description
To cancel low frequency noise out of the measured signal, every channel of the digital signal includes a first
order IIR Filter. The structure of the IIR Filter is shown in the picture below.
Figure 189 IIR-Filter Implementation Structure
(23.5)
This filter allows an effective suppression of high-frequency components like noise or crosstalk caused by HF-
components in order to avoid the generation of unwanted interrupts. The coefficient b can be expressed as:
(23.6)
With the coefficient b implemented in the IIR Filter transfer function, it looks like:
(23.7)
The IIR Filter transfer function is shown in the plot below.
IIR-Filter-Structure.vsd
+
b
0
a
1
Z
-1
Calib_Raw_Data
IIR _Data
H
IIR
(z)
=
(1
-
a
*
z
-1
)
b
0
1
1 – a
1
b
=
0
H
IIR
(z)
=
(1
-
a
*
z
-1
)
1 - a
1
1