ACPM-7813 데이터 시트보기 (PDF) - HP => Agilent Technologies
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ACPM-7813 Datasheet PDF : 21 Pages
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Design Tips to use Vcntl pin
Power Amplifier Control Using Vcntl
Pin on ACPM-7813
Power amplifier control scheme
in CDMA systems is one of the
important and challenging
aspects of CDMA-based handset
design. Handset designers must
balance maintaining adequate
linearity while optimizing
efficiency at high, medium and
low output power levels. The
primary method to achieve these
goals is to adjust the bias of the
PA as a function of output power.
Theoretically, the best efficiency
would be achieved when the bias
of the PA is continually adjusted
based on the output power
requirement of the PA. However,
implementing this type of circuit
can be complex and costly.
Therefore several different
approaches have been developed
to provide an acceptable trade-
off between optimum efficiency
and optimum manufacturability.
This application section reviews
four methods of controlling the
bias of a CDMA power amplifier:
fixed, step, logical and dynamic.
1. Fixed Bias Control
Using a fixed bias point on the
PA is the traditional method, and
it is the simplest. For example, a
fixed control voltage of 2.5V is
recommended when using
Agilent’s Power Amplifier, 2.5V
Vcntl for ACPM-7813. The Vcntl
pin on the PA is controlled by
PA_ON pin of the baseband IC.
When PA_ON is HIGH, the output
RF signal of the PA is enabled,
enabling the subscriber unit to
transmit the required data. The
switch circuit also controls the
on/off state of the PA.
Below is an example of how to
control the operation of the
ACPM-7813 using the PA_ON and
Vcntl pin of the PA.
Power Mode
PA_ON
Vcntl
Shut Down
LOW
0V
High Power
HIGH
2.5V
Power Range
—
≤ 28.5 dBm
To Duplexer
Vbias
Vdd2
Vdd1 PA
Vcntl
Battery
TxIC
Baseband
IC
Enable
Switch Circuit for PA
Vcntl
PMIC or LDO
PA_ON
Note: PMIC: Power Management IC
LDO: Low Drop Output (Regulator)
11
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