Analysis & Design of Non-Linear Amplifiers for Efficient Microwave Transmitters

Roberg, Michael Dean

Graduate Thesis Or Dissertation

Analysis & Design of Non-Linear Amplifiers for Efficient Microwave Transmitters Public Deposited

Analytics

Download PDF

Citations

Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/3x816m83f

Abstract

This thesis addresses analysis and design of high efficiency microwave power amplifiers and rectifiers. The focus of this body of work is to optimize narrow band power amplifiers for maximization of Power-Added-Efficiency (PAE) and rectifiers for maximization of RF-DC power conversion efficiency. A power amplifier performs DC-RF conversion while a rectifier performs RF-DC conversion, therefore a strong analogy exists between the two. Design with non-linear devices suffers from lack of accurate models characterizing large signal behavior, therefore measurement based techniques are often adopted in order to create high performance designs. The theoretical analysis presented in this thesis provides the microwave circuit designer intuition concerning performance expectations of design options rather than a recipe for creating a successful design. The complexity of non-linear device physics results in behavior which is often limited to qualitative description, complicating accurate model development. The presented theoretical analysis is applied to load-pull based design of S-Band and X-Band power amplifiers and S-Band power rectifiers. The measured circuits exhibit high efficiency consistent with the analysis. An implementation of a high efficiency pulsed S-band AM radar transmitter is presented along with measured results. An extension of the presented analysis is investigated in the form of a harmonic injection amplifier, which conceptually allows realization of a high power, high efficiency broadband amplifier. In summary, this thesis details 1) the load-pull measurement based design technique applied to microwave power amplifiers and rectifiers, 2) a theoretical analysis technique characterizing the performance limitations of harmonically terminated power amplifiers which may be applied to power rectifiers as well, 3) the design and measurement of several successful high efficiency power amplifiers and rectifiers and 4) interesting implementations of the presented theory in a system context.

Creator