LINEARITY ENHANCED DOHERTY POWER AMPLIFIER USING ANALOG PREDISTORTION

We propose a linearity-enhanced Doherty power amplifier using an analog predistortion (APD) technique, which incorporates an intermodulation (IM) generator. Because the IM generator is configured with antiparalleled diode structure, the resulting Doherty power amplifier behaves differently from a conventional one. Using antiphased IM generated by the hybrid coupler before the auxiliary amplifier, linearity for the whole power amplifier is improved because the IM from the main amplifier can be cancelled out at the combining section. The output power of the proposed Doherty power amplifier is observed 28 dBm at the maximum in measurement, whereas the adjacent channel leakage ratio is 18 dB improved at 5 MHz offset compared with that of the Doherty power amplifier without APD. (C) 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:403-404, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25701