TDA5252G2 INFINEON [Infineon Technologies AG], TDA5252G2 Datasheet - Page 39

• Manufacturer Part Number: TDA5252G2
• Description: ASK/FSK 915MHz Wireless Transceiver
• Manufacturer: INFINEON [Infineon Technologies AG]

Measured Magnitude of S11 of evalboard:
Figure 3-3
Above you can see the measured S11 of the evalboard. The –3dB-points are at 851MHz and
989MHz. So the 3dB-bandwidth is:
The loaded Q of the resonant circuit is:
The unloaded Q of the resonant circuit is equal to the Q of the inductor due to its losses.
An approximation of the losses of the input matching network can be made with the formula:
Data Sheet
L
OSS
=
B
−
20
Q
=
Q
U
*
f
L
U
log
=
=
−
Q



S11 measured
1
f
f
INDUCTOR
−
L
center
B
Q
Q
=
U
L
989



=
=
MHz
−
138
915
≈
20
36
*
MHz
MHz
−
log
@
851



915
1
MHz
−
=
. 6
MHz
. 6
36
63
63
=



138
=
1
8 ,
MHz
dB
39
[3 – 4]
[3 – 1]
[3 – 3]
[3 – 2]
TDA5252 G2
S11_measured_915.pcx.
Version 1.1
Application
2007-02-26