ATAB8402 Atmel, ATAB8402 Datasheet - Page 4

• Manufacturer Part Number: ATAB8402
• Description: BOARD DEMO 433MHZ RF TRANSMITTER
• Manufacturer: Atmel
• Type: Transmitterr

Specifications of ATAB8402

• Frequency: 433MHz
• Wireless Frequency: 315 MHz
• Modulation: ASK, FSK
• For Use With/related Products: ATA8402
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

4
ATA8401/ATA8402/ATA8403
The Power Amplifier (PA) is an open collector output delivering a current pulse, which is nearly
independent from the load impedance. Therefore, the output power can be controlled via the
connected load impedance. To achieve the maximum output power, the PA’s output capaci-
tance has to be compensated for by the reactive part of the load impedance so that all the power
will be delivered to the resistive load. The saturation of the PA’s output transistor is the limitation
of the voltage swing at matching. The PA’s matching principle is illustrated in
open collector output stage of the PA needs the DC current delivered by a low resistive path to
the power supply (V
choke) on the PA output (pin Ant1).
Figure 2-3.
The simple matching method of the loop antenna to the power amplifier is illustrated in
2-4 on page
ance (Z
The optimum load impedance of each transmitter is:
ATA8401 requires Z
ATA8402 requires Z
ATA8403 requires Z
||
) of the loop antenna to match the optimal load impedance of the transmitter, Z
5. The capacitors Cmatch1 and Cmatch2 transform the parallel resonance imped-
Principle of Power Amplifier Matching
I(t)
S
load,opt
load,opt
load,opt
). This low resistive path will be provided by connecting a feed inductor (RF
of (255 + j192)
of (166 + j223)
of (166 + j226)
C
PA_Out
V(t)
optimum
Zload
Vce sat
VS
I(t)
V(t)
I
Figure
9115A–INDCO–01/08
2-3. The
Figure
load,opt
.