A new power combining and outphasing modulation system for high-efficiency power amplification

Abstract

Abstract---This paper describes a new power combining and outphasing system that provides both high efficiency and linear output control. Whereas conventional outphasing systems utilize two power amplifiers, the system introduced here combines power from four or more amplifiers. The proposed technique overcomes the loss and reactive loading problems of previous outphasing systems. It provides ideally lossless power combining, along with resistive loading of the individual power amplifiers over a very wide output power range. A conceptual development illustrating the operating principles of the system is provided, along with a representative design, detailed analysis, and supporting simulations. The relation of the proposed technique to multi-level resistance compression is also described. It is anticipated that the new power combining and outphasing modulation approach will find widespread use in applications where both high linearity and high efficiency are desired.

High Efficiency Power Amplifiers for Modern Mobile Communications: The Load-Modulation Approach

“…In Figure 14, an example of how this balun combiner can be realized is shown. In the original version, Chireix proposed the use of two quarter-wavelength transmission lines sections joining at the output [15,100] (see Figure 14a), while in [114,115], a Marchand balun (see Figure 14b) and a transformer (see Figure 14c) are used, respectively.…”

Experimental Validation of a Four-Way Outphasing Combiner for Microwave Power Amplification

“…1 with connector length ℓ c = λ/2 and with the system driving a resistive load R L , the output power is given by [2]:…”

“…Following the design method in [2], X 1 and X 2 are uniquely determined by design parameter k. This parameter controls the tradeoff between output power dynamic range for optimum load modulation and the maximum variation in the phase of the load admittance seen by the four PAs. For this work, a value of k = 1.05 is chosen, corresponding to an output power ratio of approximately 10 dB for which an admittance phase of less than 2…”

“…The four-way power combining and outphasing system demonstrated in this work was recently proposed as a way to overcome the limitations of conventional outphasing techniques such as Chireix outphasing [2]. A design procedure and development of outphasing control laws have been described in [3].…”

Multi-Way Lossless Outphasing System Based on an All-Transmission-Line Combiner

“…In order to address the suboptimal loading conditions of conventional outphasing formulations, a multi-way power combining and outphasing amplifier has been introduced that provides branch PA loading conditions that are almost entirely resistive over a wide output power range [8], [9]. Four-way implementations of this approach have been demonstrated using all lumped elements in a tree structure [9], [10], and by incorporating microstrip lines with ground-referenced shunt reactive elements [11], [12].…”