TDK5100F_08 INFINEON [Infineon Technologies AG], TDK5100F_08 Datasheet - Page 29

• Manufacturer Part Number: TDK5100F_08
• Description: 434 MHz ASK/FSK Transmitter in 10-pin Package
• Manufacturer: INFINEON [Infineon Technologies AG]

In practice the RF-saturation voltage of the PA transistor and other parasitics reduce the
“critical” R
The output power P
R
The power efficiency (and the bandwidth) increase when operating at a slightly higher
R
The collector efficiency E is defined as
The diagram of Figure 17 was measured directly at the PA-output at V
the matching circuitry decrease the output power by about 1.5 dB. As can be seen from
the diagram, 550 Ω is the optimum impedance for operation at 3 V. For an approximation
of R
and
Figure 17
The DC collector current I
the load resistor R
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
Data Sheet
L
L
, as shown in Figure 17.
> R
OPT
LC
and P
.
LC
.
OUT
Output power P
10*E
Po [mW]
at other supply voltages those two formulas can be used:
L
. This is typical for overcritical operation of class C amplifiers. The
o
7
6
5
4
3
2
1
0
is reduced by operating in an “overcritical” mode characterised by
0
c
of the power amplifier and the RF output power P
o
(mW) and collector efficiency E vs. load resistor R
1000
P
E =
R
OUT
OPT
29
V
2000
~
P
~
S
O
I
R
V
C
OPT
S
RL [Ohm]
3000
10*E
Po
S
V 1.2, 2008-04-04
= 3 V. Losses in
Applications
TDK5100F
o
vary with
L
L
.
.