A 1.85 GHz band linearizer using the feedforward loop without delay lines

This paper presents a linearizer using the feedforward loop without delay lines which can be applied to personal communication system (PCS) base-station applications. This linearizer uses an IM amplifier and an auxiliary amplifier in order to remove the delay lines used in the feedforward technique. The delay line in the error loop is changed by the main power amplifier (PA) and the error amplifier is utilized to amplify the error signal which is combined with the output of the main amplifier. Two-tone signals at 1.85 GHz and 1.85125 GHz with -17 dBm/tone from synthesizers are injected into the linearizer. The main PA in the linearizer with a gain of 50 dB and an average power of 10 W was fabricated. The reduction of intermodulation distortion (IMD) is around 19 dB.