SELF BIAS CONTROL CIRCUIT OF A POWER AMPLIFIER MODULE, ESPECIALLY WITH REGARDS TO DETECTING A LEVEL OF AN INPUT SIGNAL OR AN OUTPUT SIGNAL TO CONTROL A BIAS CURRENT

摘要

PURPOSE: A self bias control circuit of a PAM(Power Amplifier Module) is provided to detect a level of an input signal or an output signal of an amplifier without using an external control signal or another integrated element, and to control a bias current of the amplifier based on the detected level, thereby extending a life of a battery. CONSTITUTION: An amplifier(10) amplifies an input signal to output the amplified signal. An output power detector(20) detects an output power level of the amplifier(10), and outputs a power detection signal in accordance with the detected level. A bias circuit(30) properly controls an amount of bias current supplied to the amplifier(10) according to the power detection signal. The output power detector(20) comprises as follows. An output power sensor detects a positive peak voltage, and clips a negative swing part. A smoothing block smoothes the power detection signal to have smooth change features.