A Comprehensive Analysis of Bandwidth and Size for Four-Types of Series-Combined Transformer-Based Doherty Output Networks: Theory and Examples
This paper presents theory-driven design guidelines for four types of series-combined transformer (SCT)-based Doherty output matching networks to maximize bandwidth (BW). Novel and intuitive methods were proposed for analyzing the series Doherty combiners. Compared with prior analyses relying solely...
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2025-01-01
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| Online Access: | https://ieeexplore.ieee.org/document/11080419/ |
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| author | Seokchul Lee John D. Cressler |
| author_facet | Seokchul Lee John D. Cressler |
| author_sort | Seokchul Lee |
| collection | DOAJ |
| description | This paper presents theory-driven design guidelines for four types of series-combined transformer (SCT)-based Doherty output matching networks to maximize bandwidth (BW). Novel and intuitive methods were proposed for analyzing the series Doherty combiners. Compared with prior analyses relying solely on ideal or insufficient models, this study systematically derives closed-form design equations based on non-ideal transformer-based practical circuit models. Doherty load modulation was clearly demonstrated for all four types using two combinations of SCT models and four capacitor configurations. Furthermore, the design parameters were simplified, and the equations were validated for both symmetrical and asymmetrical SCTs. To estimate the maximum achievable BW and identify the key design factors, four design examples of each type were compared using circuit simulations and numerical analysis. A clear trend observed across all four types is that a higher magnetic coupling coefficient results in a larger fractional BW. It is also demonstrated that the distinct “sweet spots” for the four types, when maximizing BW, depend mainly on only 2 or 3 variables, including turn ratios and/or self-inductances. SCT sizes were compared based on the sum of the two transformer dimensions. To validate the circuit model, a design example was built through a detailed procedure as the best practice, and a layout-based full-EM structure achieved close-to-theoretical BW. For further verification, four SCT-based Doherty power amplifiers were simulated and compared. |
| format | Article |
| id | doaj-art-eeb1d7b3c7b84bc6a02b52bf2d11503f |
| institution | Kabale University |
| issn | 2169-3536 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IEEE |
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| series | IEEE Access |
| spelling | doaj-art-eeb1d7b3c7b84bc6a02b52bf2d11503f2025-08-20T03:31:30ZengIEEEIEEE Access2169-35362025-01-011313032313033910.1109/ACCESS.2025.358950811080419A Comprehensive Analysis of Bandwidth and Size for Four-Types of Series-Combined Transformer-Based Doherty Output Networks: Theory and ExamplesSeokchul Lee0https://orcid.org/0000-0002-0999-9063John D. Cressler1https://orcid.org/0000-0001-8268-5135School of Electrical and Computer Engineering, Georgia Tech, Atlanta, GA, USASchool of Electrical and Computer Engineering, Georgia Tech, Atlanta, GA, USAThis paper presents theory-driven design guidelines for four types of series-combined transformer (SCT)-based Doherty output matching networks to maximize bandwidth (BW). Novel and intuitive methods were proposed for analyzing the series Doherty combiners. Compared with prior analyses relying solely on ideal or insufficient models, this study systematically derives closed-form design equations based on non-ideal transformer-based practical circuit models. Doherty load modulation was clearly demonstrated for all four types using two combinations of SCT models and four capacitor configurations. Furthermore, the design parameters were simplified, and the equations were validated for both symmetrical and asymmetrical SCTs. To estimate the maximum achievable BW and identify the key design factors, four design examples of each type were compared using circuit simulations and numerical analysis. A clear trend observed across all four types is that a higher magnetic coupling coefficient results in a larger fractional BW. It is also demonstrated that the distinct “sweet spots” for the four types, when maximizing BW, depend mainly on only 2 or 3 variables, including turn ratios and/or self-inductances. SCT sizes were compared based on the sum of the two transformer dimensions. To validate the circuit model, a design example was built through a detailed procedure as the best practice, and a layout-based full-EM structure achieved close-to-theoretical BW. For further verification, four SCT-based Doherty power amplifiers were simulated and compared.https://ieeexplore.ieee.org/document/11080419/BalunbroadbandDoherty power amplifier (PA)impedance inverterload modulationoutput matching network |
| spellingShingle | Seokchul Lee John D. Cressler A Comprehensive Analysis of Bandwidth and Size for Four-Types of Series-Combined Transformer-Based Doherty Output Networks: Theory and Examples IEEE Access Balun broadband Doherty power amplifier (PA) impedance inverter load modulation output matching network |
| title | A Comprehensive Analysis of Bandwidth and Size for Four-Types of Series-Combined Transformer-Based Doherty Output Networks: Theory and Examples |
| title_full | A Comprehensive Analysis of Bandwidth and Size for Four-Types of Series-Combined Transformer-Based Doherty Output Networks: Theory and Examples |
| title_fullStr | A Comprehensive Analysis of Bandwidth and Size for Four-Types of Series-Combined Transformer-Based Doherty Output Networks: Theory and Examples |
| title_full_unstemmed | A Comprehensive Analysis of Bandwidth and Size for Four-Types of Series-Combined Transformer-Based Doherty Output Networks: Theory and Examples |
| title_short | A Comprehensive Analysis of Bandwidth and Size for Four-Types of Series-Combined Transformer-Based Doherty Output Networks: Theory and Examples |
| title_sort | comprehensive analysis of bandwidth and size for four types of series combined transformer based doherty output networks theory and examples |
| topic | Balun broadband Doherty power amplifier (PA) impedance inverter load modulation output matching network |
| url | https://ieeexplore.ieee.org/document/11080419/ |
| work_keys_str_mv | AT seokchullee acomprehensiveanalysisofbandwidthandsizeforfourtypesofseriescombinedtransformerbaseddohertyoutputnetworkstheoryandexamples AT johndcressler acomprehensiveanalysisofbandwidthandsizeforfourtypesofseriescombinedtransformerbaseddohertyoutputnetworkstheoryandexamples AT seokchullee comprehensiveanalysisofbandwidthandsizeforfourtypesofseriescombinedtransformerbaseddohertyoutputnetworkstheoryandexamples AT johndcressler comprehensiveanalysisofbandwidthandsizeforfourtypesofseriescombinedtransformerbaseddohertyoutputnetworkstheoryandexamples |