RF SWITCHING DEVICE AND MOBILE TERMINAL USING THE SAME, ENABLING FILTER TO PASS TRANSMISSION SIGNAL THROUGH ANTENNA OF TRANSMISSION CIRCUIT SIDE IN TRANSMITTING MODE, AND PERFORM THE FUNCTION OF 1/4 WAVELENGTH IMPEDANCE TRANSFORMER IN RECEIVING MODE

摘要

PURPOSE: An RF(Radio Frequency) switching device and a mobile terminal using the same are provided to simplify a circuit and make a mobile terminal compact while satisfying loss characteristics of a receiving circuit and isolation characteristics of a transmitting circuit. CONSTITUTION: A filter(31) connected between a transmitting circuit(TX) and an antenna(ANT), passes a transmission signal received from the transmitting circuit(TX) through the antenna(ANT), and has an electrical length corresponding to approximately 1/4 wavelength of the frequency of a receiving signal in case of receiving. The first switching unit(32) connected between the filter(31) and the transmitting circuit(TX) operates the filter(31) as an impedance transformer by connecting the transmitting circuit(TX) of the filter(31) to ground by a switching signal(Ssw) to thereby alternately separate the transmitting circuit(TX) and the antenna(ANT). The second switching device(33) connected between the antenna(ANT) and the receiving circuit(RX) separates the antenna(ANT) and the receiving circuit(RX) by the switching signal in case of transmission.