TDA5251XT Infineon Technologies, TDA5251XT Datasheet - Page 39

• Manufacturer Part Number: TDA5251XT
• Manufacturer: Infineon Technologies

Specifications of TDA5251XT

• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 4.4mm
• Product Length (mm): 9.7mm
• Operating Supply Voltage (min): 2.1V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / Rohs Status: Compliant

Measured Magnitude of S11 of evalboard:
Figure 3-3
Above you can see the measured S11 of the evalboard. The –3dB-points are at 288MHz and
344MHz. 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
LOSS
=
B
−
Q
20
=
Q
U
*
U f
L
log
=
=
Q
S11 measured
−




1
INDUCTOR
f
−
f
center
L
Q
Q
B
=
U
L
344




=
=
−
MHz
20
315
≈
56
*
27
log
MHz
−
MHz
@
288




1
315
−
MHz
5
27
=
MHz
6 ,
5




6 ,
=
=
2
56
dB
MHz
39
[3 – 4]
[3 – 1]
[3 – 3]
[3 – 2]
TDA5251 F1
S11_measured_315.pcx.
Version 1.1
Application
2007-02-26