HIGH EFFICIENCY STAGE-CONVERSION TYPE POWER AMPLIFIER FOR CDMA COMMUNICATION SYSTEM

摘要

PURPOSE: A high efficiency stage-conversion type power amplifier for a CDMA(Code Division Multiplex Access) is provided to possess a two-stage amplifier having two amplifying stages to a base station, compare the power level of an input signal to a predetermined reference value and performs an amplification of the input signal by using one between two amplification stages according to the comparison result, thereby improving the amplification efficiency of the input signal. CONSTITUTION: A signal amplifier(300) receives a wireless frequency signal through an input terminal(302). An envelope detector(304) is connected to the input terminal(302) and detects a power level of the input signal. A controller(306) is connected to the envelope detector(304) and receives a signal showing the power level of the input signal from the detector(304). The controller(306) determines an amount of a proper power amplification by using a momentary power level of the input signal detected from the envelope detector(304). The controller(306) also controls an input bias voltage level of an amplifier(308) according to the power level of the input signal. The amplifier(308) connected to the input terminal(302) amplifies the input signal inputted from the input terminal(302) according to the control operation of the controller(306) and then outputs the output signal to an output terminal(310).