Abstract: A Radio Frequency (RF) transmitter and a signal amplification method therefor are provided, in which a signal source generates a signal of a predetermined Intermediate Frequency (IF) band, a local oscillator generates a signal of a predetermined high frequency band as a carrier signal, a power amplifier amplifies the signal received from the local oscillator to a predetermined transmission level, and a parametric mixer module receives the signals from the signal source and the power amplifier and outputs the received signals as a radio signal for transmission. The signal output from the parametric mixer module is transmitted as the radio signal without additional amplification.

Abstract: A Radio Frequency (RF) transmitter and a signal amplification method therefor are provided, in which a signal source generates a signal of a predetermined Intermediate Frequency (IF) band, a local oscillator generates a signal of a predetermined high frequency band as a carrier signal, a power amplifier amplifies the signal received from the local oscillator to a predetermined transmission level, and a parametric mixer module receives the signals from the signal source and the power amplifier and outputs the received signals as a radio signal for transmission. The signal output from the parametric mixer module is transmitted as the radio signal without additional amplification.

Abstract: A device and a method for combining outputs of a plurality of linear power amplifiers while preventing loss of signals.

Abstract: A feedforward-type linear power amplifier directly compares amplitude and phase of a signal applied to one input end of a first signal canceler with amplitude and phase of a signal applied to another input end of the first signal canceler, and according to the comparison results, controls a first variable attenuator and a first variable phase shifter disposed in a pre-stage of the first signal canceler so that the first signal canceler extracts only the intermodulation distortion signals generated while a main power amplifier amplifies the RF input signal. Then, the linear power amplifier directly compares amplitude and phase of the intermodulation distortion signal on a main path with amplitude and phase of the intermodulation distortion signal on a sub path, and according thereto, controls a third variable attenuator and a third variable phase shifter to cancel the intermodulation distortion signals contained in the RF output signal of the main power amplifier.

Abstract: A linear power amplifier and method for removing the intermodulation distortion with a predistortion system and a feed forward system. The linear power amplifier having a main power amplifier includes: a predistortion system for firstly suppressing the intermodulation signal generated upon amplification of an RF signal in the main power amplifier, by generating a harmonics corresponding to the input RF signal and a predistortion signal with coupling the RF signal to the harmonics; and a feed forward system for secondly suppressing the intermodulation signal by canceling the input RF signal and the output of the main power amplifier, extracting an intermodulation signal distortion, error-amplifying the extracted intermodulation signal distortion, and coupling the amplified intermodulation signal with the output of the main power amplifier.

Abstract: An improved Wilkinson-type power divider/combiner possessing switching capabilities for selectively controlling operative modes of its constituent dividing/combining channels is disclosed. The switchable power divider/combiner includes N first switches connecting N input/output transmission lines to a common junction and N second switches connecting N isolation resistors coupled to the N input/output transmission lines to a common node. The operating mode of the power divider/combiner can be controlled by activating each pair of the first and second switches to a closed or open switch position. The impedance values of the dividing/combining channel transmission lines are adjusted to provide the optimal impedance matching in both N-way and (N-1)-way operating modes. The resulting switchable power divider/combiner is capable of providing efficient power combining and distribution in a low-loss, phase-balanced manner in both N-way and (N-1)-1 way modes.