TDA5252G2 INFINEON [Infineon Technologies AG], TDA5252G2 Datasheet - Page 43

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

The diagram of Figure 3-7 has been measured directly at the PA-output at V
the matching circuit of about 3dB will decrease the output power. As shown in the diagram, 250
Ohm is the optimum impedance for operation at 3V. For an approximation of R
other supply voltages those 2 formulas can be used:
and
The behaviour of the power amplifier over the impedance and frequency is in principle the same as
of the TDA5250, but of course strongly depends on the matching network. (see also specification
of TDA5250)
Figure 3-7
The DC collector current I c of the power amplifier and the RF output power P o vary with the load
resistor R L . This is typical for overcritical operation of class C amplifiers. The collector current will
show a characteristic dip at the resonance frequency for this type of “overcritical” operation. The
depth of this dip will increase with higher values of R L .
Data Sheet
P
E =
R
OUT
OPT
V
~
P
S
~
O
R
I
C
OPT
V
S
Output power P o (mW) and collector efficiency E vs. load resistor R L .
43
[3 – 11]
[3 – 12]
[3 – 10]
S
=3V. A power loss in
OPT
TDA5252 G2
Version 1.1
Application
Power_E_vs_RL.wmf
and P
2007-02-26
OUT
at