A New Envelope Predistorter With Envelope Delay Taps for Memory Effect Compensation

We present a new linearization method for high-power amplifiers, using an envelope predistorter (EPD) including envelope delay taps and control circuits, for memory effect compensation. The lower and upper third-order intermodulation (IM
₃
) components, generated by the EPD, can be separately controlled for their magnitudes and phases by the additional memory effect compensation circuits. By using experimental results for a high-power (30-W peak envelope power) class-AB amplifier, further linearity improvement was also demonstrated using the proposed EPD. For a two-tone signal with a tone spacing of 20 MHz, the proposed EPD, with only a single delay tap, cancelled the lower and upper IM
₃
components by 20.84 and 18.17 dB, while the conventional EPD, with no envelope delay tap, cancelled them by 11.67 and 8.50 dB, respectively