APPARATUS FOR CONTROLLING TRANSMISSION POWER IN MOBILE COMMUNICATION TERMINAL

PURPOSE: An apparatus for controlling a transmission power in a mobile communication terminal is provided to prevent the unnecessary power loss of a power amplifier and increase a use time of a battery by adjusting a gain of the power amplifier in a transmission terminal of the mobile communication terminal according to a level of a receiving signal. CONSTITUTION: If a terminal is a call on state, an MSM(Mobile Station Modem)(100) outputs a PDM(Pulse Density Modulation) transmission power control signal corresponding to an RF(Radio Frequency) signal together with a power-on signal. If the terminal is a call off state, the MSM(100) outputs a power off signal. A regulator(200) receives a power(VCC) from a battery(1) and generates a 3V power. An operation amplifier(300) receives the 3V power from the regulator(200), receives the PDM transmission power control signal from the MSM(100), and outputs 0-3 reference voltages according to the level of the PDM transmission power control signal. If the reference voltage is inputted from the operation amplifier(300) after being driven by the power(VCC) of the battery(1), a power amplifier(400) determines its current amplification gain by the reference voltage. If an RF transmitting signal output from the MSM(100) is received through a transmission circuit terminal, the power amplifier(400) amplifies the power of the RF transmitting signal to be suitable for the currently set gain. If the power-on signal is received from the MSM(100), a switch(500) is turned on so that the power(VCC) of the battery(1) is supplied to the power amplifier(400). If the power on signal is received from the MSM(100), the switch(500) is turned off for blocking the power(VCC) of the battery(1).