Digital Predistortion of Envelope Tracking Amplifiers driven by slew-rate limited envelopes

This paper presents a new Digital Predistorter (DPD) to compensate for nonlinear distortion that arises in Envelope Tracking (ET) Power Amplifiers (PAs) driven by slew-rate limited versions of the real signal´s envelope. The slower version of the transmitted signal´s envelope is used to cope with the slew-rate and bandwidth limitations of Envelope Amplifiers (EAs). Unfortunately, the use of slower versions of the real signal´s envelope as the drain modulator generates a special kind of nonlinear memory effects. This paper shows experimental results that prove that is possible to compensate for these nonlinear memory effects that appear when exciting the supply of a RF linear PA with a slew-rate limited version of the envelope.