rf3145 RF Micro Devices, rf3145 Datasheet - Page 15

• Manufacturer Part Number: rf3145
• Description: Quad-band Gsm/edge/gsm850/dcs/pcs Power Amplifier Module Rf3145
• Manufacturer: RF Micro Devices

Where P
power.
The RF3145 improves the effective efficiency by minimizing the P
0.4dB to 0.5dB loss to the transit path. To demonstrate the improvement in effective efficiency consider the following exam-
ple:
Conventional PA Solution:
RF3145 Solution:
The RF3145 solution improves effective efficiency 5percent.
Output power does not vary due to supply voltage under normal operating conditions if V
By regulating the collector voltage to the PA, the voltage sensitivity is essentially eliminated. This covers most cases where the
PA will be operated. However, as the battery discharges and approaches its lower power range, the maximum output power
from the PA will also drop slightly. In this case it is important to also decrease V
switching transients. These transients occur as a result of the control loop slowing down and not regulating power in accor-
dance with V
The switching transients due to low battery conditions are regulated by incorporating the following relationship limiting the
maximum V
sation required for extreme conditions is covered by the relationship in Equation 4. This should be added to the terminal soft-
ware.
NOTE: Output power is limited by battery voltage. The relationship in Equation 4 does not limit output power. Equation 4 limits
the V
Due to reactive output matches, there are output power variations across frequency. There are a number of components that
can make the effects greater or less.
Rev A4 DS050919
η
V
EFF
RAMP
RAMP
=
PA
≤
10
------------------------------------------------ -
voltage to correspond with the battery voltage.
3
-- - V
8
is the output power from the PA, P
RAMP
V
RAMP
⋅
P
----------------------------- -
BAT
PA
BATT
+
voltage (Equation 4). Although no compensation is required for typical battery conditions, the battery compen-
.
10
P
⋅
LOSS
I
BAT
+
0.18
–
⋅
10
10
P
------- -
10
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IN
P
P
V
V
LOSS
LOSS
P
P
P
P
I
I
BAT
BAT
BAT
BAT
PA
IN
PA
IN
= +33.5 dBm
= 0 dB
= +33.5 dBm
= +3 dBm
= +3 dBm
= -0.4 dB
= 3.5 V
= 1.16 A
= 3.5 V
= 1.16 A
LOSS
the insertion loss, P
LOSS
term in the equation. A directional coupler may introduce
IN
h
η
the input power to the PA, and P
EFF
EFF
= 55.16%
RAMP
= 50.3%
to prevent the power control from inducing
RAMP
is sufficiently lower than V
RF3145
DC
the delivered DC
15 of 18
(Eq. 4)
(Eq. 3)
BATT
.