ACPM-7813 データシートの表示（PDF） - HP => Agilent Technologies
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ACPM-7813 Datasheet PDF : 21 Pages
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3. Dynamic Bias Control
Alternate Implementation
Phone designers can use
TX_ADC_ADJ pin of the
baseband IC to get dynamic bias
control with Vcntl pin of PA.
TX_ADC_ADJ is a PDM output
pin produced by the TX AGC
subsystem and used to control
the gain of the Tx signal prior to
the PA. The variable output levels
from two inverting operational
amplifiers, generated and com-
pared by TX_ADC_ADJ, provide
dynamic control voltages for the
Vcntl of 1.0V ~ 2.7V with a 0.1V
step.
To Duplexer
Battery
Vbias
Vdd2
Vdd1 PA
Vcntl
Enable
Switch Circuit
TxIC
Vcontrol
Baseband IC
R3
R1
R5
_
_
R4 V1
R2 Vin C1
+
PA_ON
TX_ADC_ADJ
Av = -(V1/Vin) = -R3/R2,
V1 = -(R3/R2)Vin,
Vo = -(R5/R4)V1= [(R5*R3)/(R4*R2)]*Vin
The using of combination of two
pins, PDM1 and TX_ADC_ADJ, is
another method of realizing a
dynamic bias control scheme.
The two OP Amps control the
Vcntl voltage levels with com-
pared and integrated circuits.
To Duplexer
Vbias
Vdd2
Vdd1 PA
Vcntl
Battery
Enable
Switch Circuit
TxIC
Vcontrol
_
_
+
+
Baseband IC
PA_ON
TX_ADC_ADJ
PDM1
13
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