TDA5200_10 Datasheet, PDF (24/39 Pages) Infineon Technologies AG – ASK Single Conversion Receiver

TDA 5200
ASK Single Conversion Receiver
Applications
4.2
Data Filter Design
Utilizing the on-board voltage follower and the two 100 kΩ on-chip resistors a 2^nd order Sallen-Key low pass data
filter can be constructed by adding 2 external capacitors between pin 19 (SLP) and pin 22 (FFB) and to pin 21
(OPP) as depicted in the following figure and described in the following formulas¹⁾.
C₁
C₂
Pins:
22
21
19
R
R
100k
100k
Figure 7 Data Filter Design
C1 = ^{2Q b}
R2Πf _3dB
C2 =
b
4QRΠf_3dB
with
Q= ^b
a
the quality factor of the poles where
in case of a Bessel filter
and thus
and in case of a Butterworth filter
and thus
a = 1.3617, b = 0.618
Q = 0.577
a = 1.141, b = 1
Q = 0.71
Example
Butterworth filter with
f_3dB = 5 kHz and R = 100 kΩ
C₁ = 450 pF, C₂ = 225 pF
1) Taken from Tietze/Schenk: Halbleiterschaltungstechnik, Springer Berlin, 1999
Data Sheet
24
(1)
(2)
(3)
Revision 3.0, 2010-12-28