Independently Tunable Linearizer Based on Characteristic Self-Compensation of Amplitude and Phase

In this paper, an independently tunable linearizer (ITL) is proposed to offer a continuous tuning and individual compensation of AM/AM and AM/PM distortion of power amplifiers (PAs). Two new operating modes of linearizer have been extended from conventional linearizer which has a correlated expansion characteristic of gain and phase, a derivative factor of the linearizer's forward S-parameter is presented to characterize the modes and aided the ITL design. By synthesizing these modes, an ITL prototype is designed and fabricated at a center frequency of 3.5 GHz. The restrictions of the derivative factors during the design are analyzed and presented first, then the ITL is tested with a continuous wave (CW) and several Long Term Evolution (LTE) signals with different bandwidth and Peak to Average Power Ratio (PAPR), respectively. The results show that the independent tuning range of AM/AM and AM/PM is measured by more than 3.4 dB and 33 degrees, and the ITL can significantly improve the linearity of PAs with wideband stimulated up to a bandwidth of 55 MHz. Two different PAs achieve over -40 dBc of Adjacent Channel Power Ratio (ACPR) with the ITL. Furthermore, the power consumption of ITL is less than 0.5 W, the performance improvement does not increase the cost compared to conventional analog linearization.