On the design of GaN Chireix power amplifiers using an embedding device model

Abstract

As wireless cellular communication keeps expanding toward higher bandwidth, multiband signals, and high frequencies of operation, the design of power efficient radio frequency power amplifiers (PAs) for cellular phone basestations is submitted to more stringent requirements. This paper discusses the promising technique of nonlinear embedding , which may help stream line the design of such PAs. To this order, the design of a GaN radio frequency PA from device modeling to circuit design is presented. The large signal modeling of GaN high-electron-mobility transistors including thermal and trapping memory effects is discussed first. The nonlinear embedding device model is then introduced using the concept of an anti-circuit transfer network. This embedding device model is then applied to the design of a Chireix amplifier. New Chireix design equations are developed to work with the memoryless inner core of the embedding device model, and their validity is confirmed in circuit simulations. The Chireix amplifier is then designed using the multi-harmonic impedance terminations predicted by the embedding device model for the package reference planes. Finally, the resulting Chireix amplifier is implemented in a circuit simulator with the original GaN high-electron-mobility transistors device model and verified in simulations to have a performance approaching that of the originally targeted Chireix at the current reference planes. These theoretical and simulation results demonstrate the potential of the nonlinear embedding PA design technique in the design of Chireix power amplifiers.

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

“…In [113], it is shown how to overcome this issue combining the non-linear embedding technique and a novel Chireix structure, where the current-generator-like behaviour of the branch PAs is transformed into the desired voltage-generator-like one by using two offset lines and two ideal transformers.…”

Waveform engineering: State-of-the-art and future trends (invited paper)

“…An interesting variant was recently proposed by Roblin: the model-based nonlinear embedding. [45][46][47] Starting from Figure 1, the idea is to directly apply the optimum impedance conditions suggested by the theory 14-21 at the CGP. To accomplish this, the device model is separated into its three different parts, i.e., a resistive core, a capacitive core, and a linear parasitic network.…”

A compact outphasing power amplifier with integrated reactive compensation

“…Inspired by these, some alternative design approaches were reported in the literature. In order to eliminate the influence of linear and nonlinear parasitic parameters, an anticircuit transfer network‐based de‐embedding method was used for outphasing PA design . This success of this technique is built upon the prior knowledge of the accurate device model, therefore limits the scope of application.…”

“…In order to eliminate the influence of linear and nonlinear parasitic parameters, an anticircuit transfer network-based de-embedding method was used for outphasing PA design. 4 This success of this technique is built upon the prior knowledge of the accurate device model, therefore limits the scope of application. In Reference 5, a network synthesization method based on load-pull results was proposed to realize impedance matching and reactive compensation.…”