TDA5212_06 INFINEON [Infineon Technologies AG], TDA5212_06 Datasheet - Page 25

• Manufacturer Part Number: TDA5212_06
• Description: ASK/FSK 915MHz Single Conversion Receiver
• Manufacturer: INFINEON [Infineon Technologies AG]

Wireless Components
4.2 Data Filter Design
Utilising the on-board voltage follower and the two 100kΩ on-chip resistors a
2nd order Sallen-Key low pass data filter can be constructed by adding 2 exter-
nal capacitors between pins 19 (SLP) and 22 (FFB) and to pin 21 (OPP) as
depicted in the following figure and described in the following formulas
Figure 4-3
with
the quality factor of the poles
where
in case of a Bessel filter a = 1.3617, b = 0.618
and thus Q = 0.577
and in case of a Butterworth filter a = 1.141, b = 1
and thus Q = 0.71
Example: Butterworth filter with f
1. taken from Tietze/Schenk: Halbleiterschaltungstechnik, Springer Berlin, 1999
C
1
= 450pF, C
Data Filter Design
Pins:
C
2
4 - 4
1
= 225pF
=
100k
R
R
2
2
22
C
Q
Π
1
f
3
3dB
b
dB
100k
Q =
R
= 5kHz and R = 100kΩ:
C
21
2
C
a
b
2
=
4
QR
Π
b
f
Specification, December 2006
19
3
dB
Applications
TDA 5212
Filter_Design.wmf
1
.