Patent ID: 6718165
Filing Date: 2004-04-06
Classification: H03G,H04B

Abstract:
An apparatus for reducing nonlinear distortion occurring in a down-converter according to a level of a received RF (Radio Frequency) signal in a receiving stage of a mobile communication system, said receiving stage including a low-noise amplifier for low-noise amplifying an RF input signal received through an antenna and outputting the amplified received RF signal, said down-converter for down-converting the amplified received RF signal to an IF (Intermediate Frequency) signal by mixing the amplified received RF signal with a reference frequency signal, and an automatic gain control (AGC) amplifier for amplifying the IF signal according to an AGC voltage to maintain a power level of the IF signal and outputting the amplified IF signal for demodulation, said apparatus comprising:a power detector for detecting a power level of the amplified received RF signal; a comparator for comparing the detected power level with a predetermined reception power threshold and generating a comparison control voltage, said comparison control voltage being inversely proportional to a difference between the detected power level and the reception power threshold; and a voltage controlled amplifier for amplifying the reference frequency signal according to the generated comparison control voltage and outputting the amplified reference frequency signal to the down-converter.