ATA5423 ATMEL Corporation, ATA5423 Datasheet - Page 20

• Manufacturer Part Number: ATA5423
• Manufacturer: ATMEL Corporation

Figure 3-9.
3.12
20
Output Power Setting and PA Matching at RF_OUT
ATA5423/25/28/29 [Preliminary]
Ref 10 dBm
Samp
Log
10
dB/
VAvg
50
W1 S2
S3 FC
Center 433.92 MHz
Res BW 10 kHz
FSK–modulated TX Spectrum (433.92MHz/20 kBaud/ 16.17 kHz/Manchester Code)
The Power Amplifier (PA) is a single–ended open collector stage which delivers a current pulse
which is nearly independent of supply voltage, temperature and tolerances due to band gap sta-
bilization. Resistor R
current in the PA. A higher resistor value results in a lower reference current, a lower output
power and a lower current consumption of the PA. The usable range of R
PWR_H switches the output power range between about 0 dBm to 5 dBm (PWR_H = GND) and
5 dBm to 10 dBm (PWR_H = AVCC) by multiplying this reference current by a factor 1
(PWR_H = GND) and 2.5 (PWR_H = AVCC), which corresponds to about 5 dB more output
power.
If the PA is switched off in TX mode, the current consumption without output stage with
VS1 = VS2 = 3 V, T
433.92 MHz.
The maximum output power is achieved with optimum load resistances R
3-7 on page 22
absorbing it into the matching network consisting of L
21. There must also be a low resistive DC path to AVCC to deliver the DC current of the power
amplifier's last stage. The matching of the PA output was done with the circuit shown in
10 on page 21
ments may be necessary to compensate for individual board layouts.
with the values in
Atten 20 dB
with compensation of the 1.0 pF output capacitance of the RF_OUT pin by
amb
1
, see
= 25°C is typically 6.5 mA for 868.3 MHz and 6.95 mA for 315 MHz and
VBW 10 kHz
Figure 3-10 on page
Table 3-7 on page
21, sets a reference current which controls the
1
22. Note that value changes of these ele-
, C
1
, C
Sweep 27.5 ms (401 pts)
Span 1 MHz
3
as shown in
1
Lopt
is 15 k to 56 k . Pin
Figure 3-10 on page
according to
4841A–RKE–02/05
Figure 3-
Table