ATA5423 ATMEL Corporation, ATA5423 Datasheet - Page 21

• Manufacturer Part Number: ATA5423
• Manufacturer: ATMEL Corporation

4841A–RKE–02/05
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
using a new load resistance of 300
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
with quality factors Q according to
case with the quality factor of Q
equivalent resistance of the inductor 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 2.7 V, whereas the low power mode (PWR_H = GND) can be used down to 2.4 V 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
Table 3-7 on page 22
/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)
OUT
C3
L1
AVCC
VPWR_H
2
22, with a frequency of 433.92 MHz and output power of
ATA5423/25/28/29 [Preliminary]
Table 3-7 on page
= 43 the loss in this inductor is estimated with the parallel
(10 nF) has to be placed close to the matching network
C1
1 mW)/(3 V 10.85 mA)
a n d
were measured with standard multi–layer chip inductors
R1
L1
loss
1.091 = 327 . The resulting output power is then
1
= 2
10
t h e
= 1.091
8
9
C2
RF_OUT
R_PWR
PWR_H
ATA5423/ATA5425/
ATA5428/ATA5429
o v e r a l l
log(1.091) = 0.38 dB less output power if
f
22. Looking to the 433.92 MHz/11 dBm
22 k = 24 k results in 9.1% less cur-
L
Q
c u r r e n t
100% = 38.6% in this case.
66.
L1
and the matching loss with
c o n s u m p t i o n
21
i s