Abstract: A power amplifier for a transmitter includes a plurality of CMOS amplifiers of different types which are serially and alternately connected, and matching circuits for matching impedance discrepancies between the CMOS amplifiers of different types.

Abstract: Disclosed is an RF transceiver including a receiver chain performing a dual conversion with respect to a received RF signal, thereby generating an IF signal; a chain of transceiver performing a dual conversion with respect to an IF signal to be transmitted, thereby generating an RF signal; and an IF SAW filter used in the receiver chain and the transmitter chain in common, the IF SAW removing an unnecessary signal generated during a first down-conversion after an IF signal having undergone the first down-conversion is IF-amplified in the receiver chain, and removing an unnecessary signal generated during a first up-conversion after an IF signal having undergone the first up-conversion is IF-amplified in the transmitter chain.

Abstract: A DC offset cancellation apparatus in a time division duplexing mode direct conversion receiver is disclosed that cancels DC offset of a present frame by using DC offset information of a previous frame by using a receive time difference between data transmission frames. Therefore, the DC offset cancellation unit has advantages of canceling the DC offset in an active mode in real time, of canceling the DC offset varying depending on time and circumferential conditions, and of minimizing power consumption by using an optimized element alignment.

Abstract: The invention relates to a duplex outdoor base station utilizing a hybrid system of a high amplifier and optic antenna to communicate over both radio and optic frequencies. The base station includes: a RF front end part interfaced with an optic antenna; a receiver interface unit for transmitting the received signal to the RF front end part after amplifying a received signal; a transceiver unit for transmitting the transmitted/received signal to the RF front end part; a base station transceiver subsystem (BTS) test unit, coupled to the front end part, for performing a self-diagnosis of a BTS; and an optic antenna interface unit for connecting an optic antenna system with the receiver interface unit. This base station transceiver subsystem (BTS) is a kind of hybrid system for simultaneously operating an optic antenna and a radio frequency antenna.