Reflective adjustable analog predistorter for dual inflection point amplifiers

In this paper, An adjustable analog predistortion linearizer for double inflection point power amplifier is proposed. In this circuit, a hybrid impedance matching network (HIMN) composed of a Schottky diode and two varactor diodes is introduced before the nonlinear load (NL). Adjusting the varactor and Schottky diode bias voltages achieves adjustable gain and phase conversion and adjustable inflection depth, respectively. A reflection linearizer circuit operating at 4.8GHz is designed and fabricated. The measurement results show that by increasing the bias voltage of the varactors, the gain expansion increases from 2.4 dB to 6.7 dB, the phase compression increases from 14.2 ° to 46.7 °. The shape of the predistortion curve can be adjusted by adjusting the Schottky diode bias voltage. The maximum adjustment range of inflection point depth is 0~4.1dB, while the gain and phase compensation are basically unchanged.