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Fachzeitschrift für Hochfrequenz- und Mikrowellentechnik

RF & Wireless S-Band

RF & Wireless S-Band IMFET Design With NI AWR Software Figure 1: Block diagram and 3D layout of IMFET Wavice, Inc. is a leading defense company in South Korea and equipped with an internal fab that provides a durable RF gallium nitride (GaN) process that has been bolstered by the recent opening of its 0.4 µm foundry service. Wavice is expanding its presence as an integrated device manufacturer within South Korea to the global market with its high reliability and high efficiency products. GaN high-electron mobility transistor (HEMT) devices have been widely adopted as a core technology of choice for many military and commercial RF applications such as longdistance radar, mobile base stations, satellite communications, and more. GaN HEMT high-power amplifiers (HPAs) provide very high efficiency, excellent power handling capabilities, and exceptional tolerance of operational temperature in a wide frequency range. Challenge Long-range radar systems with solid-state PAs often require very high-power output with a very small device size because there is limited installation space. Monolithic microwave integrated circuits (MMICs) are considered the best solution for reducing the size of HPAs, however, the development cost of MMICs can be extremely high when used in low- to medium-volume applications. Internally matching fieldeffect transistors (IMFETs), a block diagram of which is shown in Figure 1, include impedancematching circuits that reduce the size of HPAs more than 10 times, while keeping the manufacturing cost comparable to designs with unmatched discrete transistors. In addition, IMFETs keep manufacturing costs lower compared to SMT-based matching networks by reducing the bill of materials. Solution The designer chose the Microwave Office circuit simulator within NI AWR software for the IMFET design and used the large-signal model and manufacturer information for the GaN HEMT devices. Load-pull simulation was done at 48-dBm input power (Pin), -2.75 V gate voltage (V g ), 50 V drain voltage (V d ), and 1 A drain current (I d ) at 3.4 GHz, which was the center frequency of the target frequency range of 3.2 to 3.6 GHz. The matching circuit was designed based on the load-pull simulation results. Figure 2 provides the IMFET simulation results at 48 dBm P in for a 3.1...3.7 GHz frequency range. The P out and the gain show excellent flatness across the 3.2...3.6 GHz range and the PAE is over 50% for 3.2...3.6 GHz range. Figure 3 shows P out (top) and PAE (bottom) as a function of Pin for various frequencies. For 3.2...3.6 GHz frequency range, the Pout, PAE, and power gain of over 57.8 dBm, 45.5%, and 9.8 dB were measured, respectively, with 48 dBm P in . The size of the IMFET was 24 x 17.4 mm and the Pout per unit area of the NI AWR www.awr.com www.ni.com Figure 2: IMFET simulation results 46 hf-praxis 5/2020

RF & Wireless Figure 4: Comparison of simulated and measured data of P out and PAE of IMFET for 3.2...3.6 GHz Figure 3: Measured RF performance of the IMFET as a function of P in for various frequency values package was record high as 1.74 W/mm 2 . The P out , gain, and PAE were measured over 55.8 dBm, 9.8 dB, and 57.82% respectively. Figure 4 shows the comparison of simulated and measured data of P out and PAE from a typical IMFET. The measured and simulated P out and PAE are reasonably well matched. Conclusion Matching the source and drain impedances using Microwave Office software was straightforward and the load-pull analysis, tuning, and optimization features significantly reduced design time. In addition, the simulation of gold wire (Figure 1), which is important for IMFETs, was easily performed and allowed the designers to optimize the IMFET performance based on wire bond length. Key benefits of using NI AWR software were ease of use, simulation speed and accuracy, and availability of models, all of which increased the designer’s productivity. Of special note were the superiority of the optimization and tuning features, which saved significant design time. AXIEM simulations were accurate and the analysis time fast and efficient. ◄ Fachbücher für die Praxis Praxiseinstieg in die vektorielle Netzwerkanalyse Joachim Müller, 21 x 28 cm, 142 Seiten, zahlr. Abb. und Tabellen ISBN 978-3-88976-159-0, beam-Verlag 2011, 32,- € Art.-Nr.: 118100 In den letzten Jahren ist es der Industrie gelungen, hochwertige vektorielle Netzwerkanalysatoren vom schwergewichtigen Gehäuse bis auf Handheldgröße zu verkleinern. Doch dem nicht genug: Durch ausgefeilte Software wurden einfache Bedienkonzepte bei steigender Funktionalität erreicht. Auch für den Funkamateur wird neuerdings die Welt der Netzwerkanalyse durch Selbstbauprojekte, deren Umfang und Funktionalität den Profigeräten sehr nahe kommen, erschlossen. Damit sind die Voraussetzungen für die Anwendung der vektoriellen Netzwerkanalyse im Feldeinsatz aus Sicht der verfügbaren Gerätetechnik geschaffen. Fehlte noch die geräteneutrale Anleitung zum erfolgreichen Einstieg in die tägliche Praxis. Das in Hard- und Software vom Entwickler mit viel Engagement optimal durchkonstruierte Gerät büßt alle seinen hervorragenden Eigenschaften ein, wenn sich beim Messaufbau grundlegende Fehlerquellen einschleichen. Dieses Buch beschäftigt sich mit den Grundlagen des Messaufbaus, unabhängig vom eingesetzten Gerät, um den Praxiseinstieg zu meistern. Unser gesamtes Buchprogramm finden Sie unter www.beam-verlag.de oder bestellen Sie über info@beam-verlag.de hf-praxis 5/2020 47

hf-praxis

PC & Industrie

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