A Nonlinear Filter-Based Volterra Model With Low Complexity for Wideband Power Amplifiers
A nonlinear filter-based Volterra model with low complexity is proposed for modeling and characterizing wideband power amplifiers. This model has a similar form of a simplified second-order dynamic deviation reduction (DDR)-based Volterra model but without complex square root calculations and high order terms, which are replaced by a first-order nonlinear filter. The model parameters with smaller magnitude distribution range and lower precision in storing and calculation can be estimated by least-square method, and then the model has lower complexity than the second-order simplified DDR Volterra model. Experimental results verified that good performance and lower complexity can be achieved by using this model for a wideband Doherty power amplifier. Finally, the model is employed to compensate the nonlinearity of the Doherty power amplifier, and over 12 dB adjacent channel leakage ratio (ACLR) improvement is achieved for a five-carrier long-term evolution advanced (LTE-A) signal of 100 MHz bandwidth.