APPARATUS AND METHOD FOR DIRECTLY CONVERTING FREQUENCY OF MOBILE COMMUNICATION SYSTEM

摘要

PURPOSE: An apparatus and a method for directly converting the frequency of a mobile communication system is provided to reduce the number of local oscillators to simplify the circuit. CONSTITUTION: In an apparatus for converting the frequency of a mobile communication system, a variable local oscillator(300) oscillates a frequency variable according to communication channels. A fixed local oscillator(312) oscillates a fixed frequency for generating a base band signal. The first mixer mixes the variable frequency with a reception radio frequency signal. The second mixer mixes the output of the first mixer with the fixed frequency to convert the mixed signal into a reception base band signal. The third mixer mixes the variable frequency with the fixed frequency. The fourth mixer mixes a transmission base band signal with the output of the third mixer to convert the mixed signal into a transmission radio frequency signal.