Linearization of Multi-Octave Power Amplifiers with Strong Memory Effects

Multi-octave power amplifiers (PAs) with strong memory effects often cannot be well approximated with the existing digital predistortion (DPD) models due to the overlapping between the operating band and the envelope band. A novel envelope-modulated memory polynomial (EMMP) model is proposed in this letter to linearize such ultra wideband PAs. The envelope modulation on the supply rail is incorporated into the conventional memory polynomial (MP) model in order to enhance the modelling of memory effects. Experiments were performed on a 1 MHz-3100 MHz PA. The PA was driven at 600MHz and 2600-MHz carrier frequencies using a 16QAM 10-MHz bandwidth signal. After the proposed DPD, the adjacent channel power ratio (ACPR) was improved from -33 dBc to -49 dBc and the error vector magnitude (EVM) was improved by about 13 dB.