RMPA0951AT Ver la hoja de datos (PDF) - Fairchild Semiconductor
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RMPA0951AT Datasheet PDF : 11 Pages
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DC Power Management for Reduced-Power Operating Modes
Many Cellular/PCS handsets can benefit from gain control and DC power management to optimize transmitter performance
while operating at backed-off output power levels. Oftentimes, cellular systems will operate at 10-20dB back-off from
maximum-rated linear power and peak power-added efficiency. The ability to reduce current consumption under these
conditions, without sacrificing linearity, is critical to extending battery life in nextgeneration mobile phones.
The RMPA0951AT PA offers the ability to lower quiescent current by more than 60 percent and small-signal gain by 10-
12dB using a single control voltage (Vref). Even with the amplifier biased for lowest current consumption, high linearity is
maintained over the full operating temperature range and at output power levels up to +16dBm. Bias and gain control
through Vref provides complete flexibility for the handset designer, allowing the user to define the operation by either an
analog (continuously-variable) or digital (discrete-step) voltage input. As an example, reducing the Vref voltage from 3.0V
(nominal) to 2.2V can lower PA current consumption by more than 20 percent at an output power of +12dBm.
The following charts demonstrate analog and digital control techniques for minimizing DC power consumption at reduced
RF output power levels. The first four graphs characterize analog control over a reference voltage (Vref) range of 1.8V to
3.0V. Using analog bias control, quiescent current is reduced to less than 30 mA and small-signal gain is reduced by 12dB
at Vref = 1.8V. Operating current at +12dBm is also reduced by 20 percent (25 mA) at Vref = 2.2V and by more than 50
percent (50 mA) at the lowest reference voltage (Vref =1.8V) compared with fixedbias operation at Vref = 3.0V. In all cases,
DC current savings is achieved while fully complying with IS-95 linearity requirements.
The last four graphs feature digital control performance using three discrete voltage levels (3.0V, 2.2V, 1.8V) to optimize
linear PA performance over three output power ranges (< +4dBm, +4dBm to +16dBm, >+16dBm). Alternate output power
ranges can be selected depending on the power-probability use in the cellular system.
Cellular PAM-Digital Control Mode
Parameter
Low-Power Range
Current
Gain
Linearity
Mid-Power Range
Current
Gain
Linearity
High-Power Range
Current
Gain
Linearity
Min
Typ
Max
Units
Conditions
+8
dBm
Vref = 1.8V typ
50
mA
24
dB
-50
dBc
+8
+12
+16
dBm
Vref = 2.2V typ
120
mA
28.5
dB
-50
dBc
+16
+28
dBm
Vref = 3.0V typ
540
mA
Pout = +28dBm
32.5
dB
-38
dBc
©2004 Fairchild Semiconductor Corporation
RMPA0951AT Rev. D
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