RF3145PCBA-41X RFMD [RF Micro Devices], RF3145PCBA-41X Datasheet - Page 15

• Manufacturer Part Number: RF3145PCBA-41X
• Description: QUAD-BAND GSM/EDGE/GSM850/DCS/PCS POWER AMPLIFIER MODULE
• Manufacturer: RFMD [RF Micro Devices]

Where P
the formula becomes (Equation 3):
Where P
ered DC power.
The RF3145 improves the effective efficiency by minimizing the P
introduce 0.4dB to 0.5dB loss to the transit path. To demonstrate the improvement in effective efficiency consider the fol-
lowing example:
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
V
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
the power control from inducing switching transients. These transients occur as a result of the control loop slowing down
and not regulating power in accordance with V
The switching transients due to low battery conditions are regulated by incorporating the following relationship limiting
the maximum V
tery compensation required for extreme conditions is covered by the relationship in Equation 4. This should be added to
the terminal software.
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 050919
η
V
BATT
EFF
RAMP
. By regulating the collector voltage to the PA, the voltage sensitivity is essentially eliminated. This covers most
=
≤
N
PA
10
------------------------------------------------ -
3
-- - V
8
is the sum of all positive and negative RF power, P
RAMP
is the output power from the PA, P
V
⋅
P
----------------------------- -
BAT
PA
BATT
RAMP
+
10
voltage to correspond with the battery voltage.
P
⋅
LOSS
I
BAT
+
voltage (Equation 4). Although no compensation is required for typical battery conditions, the bat-
0.18
–
⋅
10
10
P
------- -
10
IN
P
P
V
V
LOSS
LOSS
P
P
P
P
I
I
BAT
BAT
BAT
BAT
PA
IN
PA
IN
= +33.5 dBm
= +3 dBm
= -0.4 dB
= 3.5 V
= 1.16 A
= +33.5 dBm
= +3 dBm
= 0 dB
= 3.5 V
= 1.16 A
RAMP
LOSS
.
the insertion loss, P
IN
the input power and P
η
LOSS
EFF
h
EFF
= 50.3%
IN
term in the equation. A directional coupler may
= 55.16%
the input power to the PA, and P
DC
is the delivered DC power. In dB
RAMP
is sufficiently lower than
RF3145
RAMP
DC
to prevent
the deliv-
(Eq. 4)
(Eq. 3)
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