A Comparison for a Doherty power amplifier linearized using digital predistortion and feedforward compensation

A Doherty power amplifier (PA) is linearized using digital predistortion (DPD) and feedforward compensation. Power consumption and ACLR of the linearized PAs are measured and compared for a WCDMA signal. The PA used as the test device corresponds to the main amplifier of a feedforward power amplifier (FFPA). For the DPD tests, the error amplifier is turned off. For a given DC supply voltage, the DPD-compensated PA has better efficiency and worse ACLR than the FFPA. The efficiencies of the FFPA and DPD-corrected PA become similar when the DC supply voltage can be reduced because the DPD solution requires a higher supply voltage than the FFPA to meet the ACLR specification.