Abstract: A linear amplification with nonlinear components (LINC) power transmitter is provided. The LINC power transmitter includes a digital signal processing unit which controls the LINC power transmitter; a frequency modulation unit which modulates or converts a digital signal output from the digital signal processing unit into a radio-frequency (RF) signal; a signal amplification unit which amplifies the RF signal output from the frequency modulation unit using a gain amplifier and a power amplification module; and a direct current/direct current (DC/DC) conversion unit which controls bias of the power amplification module. Here, the DC/DC conversion unit controls a base bias and/or a collect bias of the power amplification module, and the power amplification module operates in saturation.

Abstract: A feedforward amplifier, and a method of improving the performance thereof, are provided. More particularly, a feedforward amplifier using imperfect cancellation of a main signal and a method of improving the performance thereof, in which, by including a predetermined amount of a main signal in an error signal that is input to an error signal cancellation loop of the feedforward amplifier, more error components of a final output signal are removed, such that the linearity and efficiency of the final output signal improve.

Abstract: A predistortion linearizer for predistorting a radio frequency(RF) signal includes a power divider, an even order harmonics generator and a predistortion component producer. The power divider divides the RF signal into a first and a second RF signals. The even order harmonics generator, responsive to the second RF signal, generates one or more even order harmonics of the fundamental frequencies. And, the predistortion component producer produces one or more odd order harmonics from the fundamental frequencies and the even order harmonics to provide a predistorted RF signal including the fundamental frequencies and the odd order harmonics. The power divider divides the RF signal into first and second RF signals and delays the first RF signal.

Abstract: A signal amplifier includes a splitter for splitting an input signal into first and second signals, first and second bias control networks for generating a base bias signal for a Doherty amplifier in accordance with a power level of the input signal, a carrier amplifier for amplifying the first input signal, a peaking amplifier for amplifying the second input signal and a Doherty output network for combining the amplified signals. Through a simplified transformation of characteristic impedances in the Doherty output network, minimization of circuitry including the signal amplifier is obtained. Further, by controlling the Doherty amplifier in accordance with the power level of the input signal, both high efficiency and high linearity of the signal amplifier are achieved.

Abstract: A so-called microwave Doherty amplifier is provided. The microwave Doherty amplifier employs a way-extension method by which N ways (N≧2 N is a natural number) are established, and an envelope tracking method so that high efficiency and linearity of the power amplifier of a mobile communications base station or a handset can be achieved and price competitiveness and reliability of an apparatus employing the Doherty amplifier can be improved. The Doherty amplifier comprises N ways, where N≧2 and N is a natural number; a carrier amplifier which is placed on one of the N ways; peak amplifiers which are placed on respective ways of the (N−1 ways excluding the way on which the carrier amplifier is placed; a power distribution unit which distributes power to each of the N ways; and a quarter wave impedance transformer at which the N ways meet.

Abstract: A feedforward amplifier which is one of the leading element of linearization systems for mobile communications base stations, and a method of improving the performance thereof, are provided. More particularly, provided are a feedforward amplifier using imperfect cancellation of a main signal and a method of improving the performance thereof, in which by including a predetermined amount of a main signal in an error signal that is input to an error signal cancellation loop of the feedforward amplifier, more error components of a final output signal are removed such that the linearity and efficiency of the final output signal improve.

Abstract: A linearized amplification apparatus includes a means for dividing an input signal into a main channel signal and a subsidiary channel signal, a PAR (Peak-to-Average power Ratio) adjustment block for reducing a PAR of the main channel signal to generate a sub-main signal having a reduced PAR compared to the PAR of the main channel signal, an error extraction block for extracting an error signal from the subsidiary channel signal and amplifying the error signal, the amplified error signal corresponding to distortion components in the sub-main signal, and a means for coupling the sub-main signal with the amplified error signal to generate an output signal having an increased PAR compared to the PAR of the sub-main signal.

Abstract: Quarter wave transformers are connected to final outputs of a carrier amplifier and a peaking amplifier, which are coupled in parallel to each other, so as to induce a Doherty operation of a microwave Doherty amplifier. Load matching circuits for obtaining a microwave output matching are connected to output terminals of the carrier amplifier and the peaking amplifier. A phase tuning component is positioned behind the load matching circuit. Accordingly, a matching state can be maintained without being changed at a high power level but can be adjusted depending on phase variations at a low power level to attain efficiency enhancements and optimum linearity.

Abstract: Quarter wave transformers are connected to final outputs of a carrier amplifier and a peaking amplifier, which are coupled in parallel to each other, so as to induce a Doherty operation of a microwave Doherty amplifier. Load matching circuits for obtaining a microwave output matching are connected to output terminals of the carrier amplifier and the peaking amplifier. A phase tuning component is positioned behind the load matching circuit. Accordingly, a matching state can be maintained without being changed at a high power level but can be adjusted depending on phase variations at a low power level to attain efficiency enhancements and optimum linearity.