State-of-the-Art Design Techniques for Efficient and Linear RF and Microwave Power Amplifiers

The focus of this talk is on state-of-the-art techniques to improve the linearity-efficiency tradeoff in RF power amplifiers (PAs) excited by wideband signals. At first, an algorithm capable of generating multi-tone signals with arbitrary bandwidth (or band distribution) and a set peak-to-average ratio (PAR) is introduced and used to create realistic operating conditions for PAs. Next, an overview of PA linearization techniques such as digital pre-distortion (DPD) and analog pre-distortion (APD) will be provided with examples up to K-band and with modulation bandwidths up to 750MHz. A brief overview of PA efficiency-enhancement techniques such as Envelope-Tracking (ET), Doherty and Outphasing PAs will be provided. Overall PA architecture efficiency can only be maximized by individually optimizing the constituent PA bandwidth and efficiency. This can be achieved by harmonically tuning the constituent PAs. An example of a very wideband Doherty PA with over 1GHz bandwidth between 2.1 and 3.2GHz and with high average drain efficiency of 65% at 8–9dB backoff is provided.