ACPM-7833-TR1 데이터 시트보기 (PDF) - Avago Technologies
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ACPM-7833-TR1 Datasheet PDF : 20 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 compared 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 compared 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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