TRANSMITTING/RECEIVING APPARATUS OF MOBILE COMMUNICATION SYSTEM, ESPECIALLY RELATED TO IMPROVING CHARACTERISTICS OF SYSTEM AND EFFICIENCY OF PARTS BY SHARING HIGH FREQUENCY FILTER IN HIGH FREQUENCY TRANSMITTING/RECEIVING PATH

摘要

PURPOSE: A transmitting/receiving apparatus of a mobile communication system is provided to enhance characteristics of a system and efficiency of parts and reduce a design area by sharing nonlinearity of an amplifier and a high frequency filter. CONSTITUTION: A low-pass filter(1) low-pass filters a received baseband signal. A modulator(2) modulates a signal outputted from the low-pass filter(1) to an IF(Intermediate Frequency) signal. An AGC(Automatic Gain Controller)(3) automatic-gain-controls the IF signal of the modulator(2) to a suitable level. The first mixer(5) mixes the IF signal with a local oscillation frequency to up-convert it to an RF(Radio Frequency) signal. A transmission/reception RF band filter(100) cancels a noise component of the up-converted RF signal outputted from the first mixer(5). The first RF AGC(7) automatic-gain-controls a signal outputted from the transmission/reception RF band filter(100) to a suitable level. A transmission/reception RF band filter(200) cancels a noise component of a signal outputted from the first RF AGC(7). A power amplifier(9) amplifies a signal outputted from the transmission/reception RF band filter(200). An isolator(10) passes only a signal outputted from the power amplifier(9) in a transmission mode. A switch(11) is switched to radiate an RF signal outputted through the isolator(10), through an antenna.