Broadband Power Amplifier Design via Fictitious Matching
Sedat Kılınç, Binboğa Sıddık Yarman, Serdar Özoğuz
Abstract
In this brief, we introduce a new matching concept, so called Fictitious Matching (FM), which may be defined between the artificially generated non-Foster passive immittances, namely <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}_{GF}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}_{LF}$ </tex-math></inline-formula> , over a lossless two-port or equivalently equalizer [E]. These immittances may not necessarily belong to physical devices, rather, they are fabricated like a source-pull or load-pull impedances to maximize the gain, the output power, the efficiency, and to minimize the output harmonics of a nonlinear-active device. In FM problems, [E] is constructed to optimize the power transfer from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}_{GF}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}_{LF}$ </tex-math></inline-formula> in the passband. In this regard, [E] is described by means of its back end driving point input immittance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}({\lambda })$ </tex-math></inline-formula> in Darlington sense, and it is determined as the outcome of the optimization process, where the complex variable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\lambda } = {\Sigma }+{j}{\Omega }$ </tex-math></inline-formula> refers to Richards variable. Synthesis of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}({\lambda })$ </tex-math></inline-formula> results in [E], consists of commensurate transmission lines. It is demonstrated that the new concept of FM can be utilized to build broadband power amplifiers. In this brief, solving FM problem successively, the input and the output matching networks of a power amplifier are designed over 500 MHz-3 GHz with the average gain of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${11}.{5}{dB}$ </tex-math></inline-formula> , the output power of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${40}.{5}{ }{dBm}$ </tex-math></inline-formula> , and the average drain efficiency of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${61}.{7}{\%}$ </tex-math></inline-formula> . The Power Amplifier was manufactured with microstrip lines using Wolfspeed’s CGH40010F <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${GaN}$ </tex-math></inline-formula> transistor.