| 摘要 |
PURPOSE: An apparatus for controlling the voltage of a power amplifier in a wireless terminal is provided to prevent power from being unnecessarily consumed by effectively supplying control voltage. CONSTITUTION: A TX_agc power is supplied to the base terminal of a transistor(TR). A power of Vc is inputted to the collector terminal of the transistor(TR). The output of the emitter terminal of the transistor(TR) is connected between the first resistor(R1) and the second resistor(R2). The first resistor(R1) is connected with the Vc power, and the second resistor(R2) is grounded. Also the output of the emitter terminal of the transistor(TR) is connected to the positive terminal(+) of an OP-Amp(813). The third resistor(R3), which is grounded, is connected to the negative terminal(-) of the OP-Amp(813). The fourth resistor(R4) is connected between the positive and negative terminals(+,-) of the OP-Amp(813). The output of the OP-Amp(813) is supplied to a power amplifier(711) as a reference voltage(Vref). Based on the supplied reference voltage(Vref), the power amplifier(711) executes amplification for an input signal.
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