ATA5423_06 ATMEL [ATMEL Corporation], ATA5423_06 Datasheet - Page 21

• Manufacturer Part Number: ATA5423_06
• Description: UHF ASK/FSK Transceiver
• Manufacturer: ATMEL [ATMEL Corporation]

4841C–WIRE–05/06
Example:
According to
11 dBm the overall current consumption is typically 17.8 mA; hence, the PA needs
17.8 mA - 6.95 mA = 10.85 mA in this mode, which corresponds to an overall power amplifier
efficiency of the PA of (10
Using a higher resistor in this example of R
rent in the PA of 10.85 mA/1.091 = 9.95 mA and 10 × log(1.091) = 0.38 dB less output power if
using a new load resistance of 300Ω × 1.091 = 327Ω. The resulting output power is then
1 1 d B m – 0 . 3 8 d B = 1 0 . 6 d B m
6.95 mA + 9.95 mA = 16.9 mA.
The values of
quality factors Q according to
with the quality factor of Q
r e s i s ta n c e o f t h e i n d u c to r R
10 log (1 + R
the PA efficiency is then 42% instead of 38.6%.
Be aware that the high power mode (PWR_H = AVCC) can only be used with a supply voltage
higher than 2.7V, whereas the low power mode (PWR_H = GND) can be used down to 2.4V as
can be seen in the
The supply blocking capacitor C
because of the RF current flowing through it.
Figure 3-10. Power Setting and Output Matching
Lopt
Table 3-7 on page 22
Table 3-7 on page
/R
loss
“Electrical Characteristics: General” on page
) which is equal to 0.32 dB losses in this inductor. Taking this into account,
RF
(11dBm/10)
L1
OUT
= 43 the loss in this inductor is estimated with the parallel equivalent
C3
Table 3-7 on page
AVCC
l o s s
VPWR_H
× 1 mW)/(3 V × 10.85 mA) × 100% = 38.6% in this case.
2
22, with a frequency of 433.92 MHz and output power of
were measured with standard multi-layer chip inductors with
(10 nF) has to be placed close to the matching network
C1
= 2 × π × f × L × Q
a n d
R1
L1
1
10
= 1.091 × 22 kΩ = 24 kΩ results in 9.1% less cur-
8
t h e
9
C2
RF_OUT
R_PWR
PWR_H
ATA5423/ATA5425/
22. Looking to the 433.92 MHz/11 dBm case
ATA5428/ATA5429
o v e r a l l
L 1
ATA5423/25/28/29
c u r r e n t
a n d t h e m a tc h i n g l o s s w i t h
67.
c o n s u m p t i o n
i s
21