PURPOSE: A power amplifying module is provided to control bias of a power amplifier as desired by inserting a sensor PMOS into a Power PMOS of an LDO(Low Dropout). CONSTITUTION: A main LDO(10) conducts only output current between an input node and an output node according to a level of controlled output voltage. The main LDO compares lamp voltage with feedback voltage. An LDO control circuit(12) generates a linear control signal having a voltage level in proportion with difference between the lamp voltage and the feedback voltage. A power PMOS(14) is connected between the input node and output node. The power PMOS is controlled by the output signal of the LDO control circuit. A current sensor(20) comprises a sensor PMOS(24), a switch(26) and a current detecting circuit(22) in order to sense the current of the main LDO.
