{"title":"150 GHz-Band Compact Phased-Array AiP Module for XR Applications Toward 6G","authors":"Yohei Morishita;Ken Takahashi;Ryosuke Hasaba;Akihiro Egami;Tomoki Abe;Masatoshi Suzuki;Tomohiro Murata;Yoichi Nakagawa;Yudai Yamazaki;Sunghwan Park;Takaya Uchino;Chenxin Liu;Jun Sakamaki;Takashi Tomura;Hiroyuki Sakai;Hiroshi Taneda;Kei Murayama;Yoko Nakabayashi;Shinsuke Hara;Issei Watanabe;Akifumi Kasamatsu;Kenichi Okada;Koji Takinami","doi":"10.1109/LMWT.2025.3565729","DOIUrl":"https://doi.org/10.1109/LMWT.2025.3565729","url":null,"abstract":"To realize the practical application of sub-THz band wireless communication toward 6G, it is necessary to develop AiP modules with compact size and low cost. This letter discusses the design of a miniaturized AiP module for high-speed wireless communication targeting extended reality (XR) applications in medical operating rooms as an example of 6G use cases. By integrating waveguide antenna array along with a compact divider/combiner within the multilayer substrates, the module achieves a small form factor of <inline-formula> <tex-math>$8.42times 20.0times 1.37$ </tex-math></inline-formula> mm while integrating radio frequency integrated circuit (RFIC) and peripheral surface mount components. The measurement shows a data rate of 40 Gb/s at a 3 m distance in the 150 GHz band with an excellent transmission energy efficiency of 35.7 pJ/bit.","PeriodicalId":73297,"journal":{"name":"IEEE microwave and wireless technology letters","volume":"35 6","pages":"920-923"},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11023526","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144299278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Wideband Continuously-Tunable Quasi-Reflectionless Filtering Attenuator","authors":"Jianxing Li;Jitao Chen;Weiyu He;Yi Song;Zhongxian Zheng;Kai-Da Xu","doi":"10.1109/LMWT.2025.3574206","DOIUrl":"https://doi.org/10.1109/LMWT.2025.3574206","url":null,"abstract":"This letter presents a continuously-tunable quasi-reflectionless filtering attenuator (QRFA). The continuous attenuation control is achieved by adjusting the bias voltage of the p-i-n diodes. By using two <inline-formula> <tex-math>$lambda $ </tex-math></inline-formula>/4 transmission lines instead of traditional grounding vias, the conflict between dc power supply and RF signal absorption is resolved, thereby realizing both quasi-reflectionless characteristic and continuously-tunable attenuation. Through a theoretical analysis based on the odd- and even-mode method, a prototype is designed and fabricated to operate at 2 GHz, which obtains a broad fractional bandwidth of 80%. Measurement results show that a wide continuously-tunable attenuation range of 3.2–23.8 dB is achieved while maintaining quasi-reflectionless characteristics from 0 to 4 GHz.","PeriodicalId":73297,"journal":{"name":"IEEE microwave and wireless technology letters","volume":"35 9","pages":"1304-1307"},"PeriodicalIF":3.4,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145078687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"High-Efficiency High-Power Wideband Power Amplifier Design With Hybrid Class AB","authors":"Engin Cagdas;Oguzhan Kizilbey;Metin Yazgi","doi":"10.1109/LMWT.2025.3555003","DOIUrl":"https://doi.org/10.1109/LMWT.2025.3555003","url":null,"abstract":"This letter presents a wideband (1.8–6 GHz) high efficiency Gallium Nitride (GaN) power amplifier (PA). The design of the PA employs an approach of large signal bandwidth (BW)-current conduction angle (CCA) relationship based on the harmonic distortion (HD) performance. This is a new approach and targets to obtain better efficiency while keeping increase of HD low in the BW. The fabricated PA offers power gain (<inline-formula> <tex-math>$P_{text {gain}}$ </tex-math></inline-formula>) of 9.6 dB, an output power (<inline-formula> <tex-math>$P_{text {out}}$ </tex-math></inline-formula>) of 37.6 dBm, a power added efficiency (PAE) ranging from 42% to 51%, and HD levels below −20 dBc throughout the 1.8–6 GHz frequency band.","PeriodicalId":73297,"journal":{"name":"IEEE microwave and wireless technology letters","volume":"35 9","pages":"1344-1347"},"PeriodicalIF":3.4,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145078617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Novel Waveguide Matched Load Based on Spoof Surface Plasmon Polaritons","authors":"Huali Zhu;Yong Zhang;Zhang Dang;Bo Yan","doi":"10.1109/LMWT.2025.3563449","DOIUrl":"https://doi.org/10.1109/LMWT.2025.3563449","url":null,"abstract":"In this letter, a novel waveguide matched load is proposed by exploiting the natural bandstop of spoof surface plasmon polaritons (SSPPs) and the ohmic loss of metal nickel (Ni). The designed waveguide matched load composes of a periodic metallic Ni-based SSPPs and an AlN substrate, which is directly embedded in the center of the <italic>E</i>-plane of the standard WR10 rectangular waveguide. Experimental results demonstrate that the electromagnetic waves can be efficiently captured and absorbed within specific frequency ranges, which exhibit an excellent VSWR performance with a return loss better than 18 dB from 85 to 100 GHz. The proposed prototype possesses the merits of high-absorption rate and low-implementation difficulty, which may provide a solution for further breakthroughs in the microwave and millimeter wave solid-state devices.","PeriodicalId":73297,"journal":{"name":"IEEE microwave and wireless technology letters","volume":"35 8","pages":"1174-1177"},"PeriodicalIF":3.4,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Knowledge-Based Extrapolation of Neural Network Model for Transistor Modeling","authors":"Jinyuan Cui;Lei Zhang;Humayun Kabir;Zhihao Zhao;Rick Sweeney;Qi-Jun Zhang","doi":"10.1109/LMWT.2025.3562538","DOIUrl":"https://doi.org/10.1109/LMWT.2025.3562538","url":null,"abstract":"Artificial neural network (ANN) is a useful technique for active device modeling. However, it shows limitations in the extrapolation region. To address this issue, we propose a novel knowledge-based neural network (KBNN) method. The KBNN technique consists of three submodels and their transition mechanisms. One submodel is a pure ANN model which is used for training data region. Two additional submodels are used for the extrapolation region. The proposed method ensures that the output and derivatives of ANN and extrapolation models match at the boundary of the measurement data. This keeps the KBNN model smooth and consistent, making it suitable for transistor design over a broad range. The precision, smoothness, and consistency of the proposed method are verified with a <inline-formula> <tex-math>$2times 250~mu $ </tex-math></inline-formula>m GaN HEMT device modeling. The results show that the KBNN model provides physically reasonable predictions over a wide extrapolation region.","PeriodicalId":73297,"journal":{"name":"IEEE microwave and wireless technology letters","volume":"35 6","pages":"812-815"},"PeriodicalIF":0.0,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144299315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Arne Fischer-Bühner;Lauri Anttila;Alberto Brihuega;Manil Dev Gomony;Mikko Valkama
{"title":"Predistortion of GaN Power Amplifier Transient Responses in Time-Division Duplex Using Machine Learning","authors":"Arne Fischer-Bühner;Lauri Anttila;Alberto Brihuega;Manil Dev Gomony;Mikko Valkama","doi":"10.1109/LMWT.2025.3561227","DOIUrl":"https://doi.org/10.1109/LMWT.2025.3561227","url":null,"abstract":"The extensive use of time-division duplexing in 5G and 6G poses a challenge to the linear operation of the power amplifiers (PAs) in radio base stations. Particularly with gallium nitride (GaN) technology, the PAs can produce strong transient behavior when resuming from an idle state, which degrades the first few transmitted symbols. This article proposes a novel machine learning technique to model and compensate the PA gain transient, based on a lightweight, low-rate recurrent model. Our RF measurements at 3.6 GHz examine the joint application of transient compensation and predistortion of short-term effects and show a successful mitigation of both types of distortion.","PeriodicalId":73297,"journal":{"name":"IEEE microwave and wireless technology letters","volume":"35 6","pages":"924-927"},"PeriodicalIF":0.0,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10980633","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144299155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Enhanced Space-Mapping Neural Network Incorporating a Dynamic Scaling Layer for Parametric Modeling of Microwave Components","authors":"Shuxia Yan;Yuxing Li;Xiaotong Lu;Jia Nan Zhang","doi":"10.1109/LMWT.2025.3562616","DOIUrl":"https://doi.org/10.1109/LMWT.2025.3562616","url":null,"abstract":"Space-mapping neural network (SMNN) technology has been widely applied for parametric modeling of microwave components. However, existing SMNN technologies struggle to address the challenges posed by the unknown and unevenly distributed numerical outputs of the mapping neural network (MNN). This letter proposes an enhanced SMNN structure that incorporates a dynamic scaling layer to tackle with this challenge. In the proposed structure, the equivalent circuit model is used as a coarse model. The relationship between the geometrical parameters and circuit element values is learned by an MNN. The numerical distribution of the MNN’s outputs is adjusted by the dynamic scaling layer with additional scaling factors for the circuit element values. A two-stage modeling method is proposed to train the enhanced SMNN structure. Using the proposed enhanced SMNN structure allows us to integrate the regulation of the numerical distribution of the MNN’s outputs into an automated framework, avoiding the risk of gradient vanishing or explosion during the training process, consequently achieving a higher modeling accuracy. Two microwave modeling examples are used to demonstrate the advantages of the proposed method.","PeriodicalId":73297,"journal":{"name":"IEEE microwave and wireless technology letters","volume":"35 8","pages":"1102-1105"},"PeriodicalIF":3.4,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Real-Time Flexible Temporal Sequence RF Spectrum Sniffer With RF Processing Group Delay Network","authors":"Hanxiang Zhang;Hao Yan;Powei Liu;Saeed Zolfaghary Pour;Bayaner Arigong","doi":"10.1109/LMWT.2025.3560563","DOIUrl":"https://doi.org/10.1109/LMWT.2025.3560563","url":null,"abstract":"In this letter, a real-time spectrum sniffer is presented to achieve flexible temporal sequence from radio frequency (RF) signal processing group delay network (GDN). The proposed sniffer is composed of a Wilkinson power divider and two branches of RF processing GDN, where multiple group delay units (GDUs) are cascade. The GDU is an RF processing function designed from a coupler and a feedback delay line, where the variable group delay is realized by controlling the electrical length of feedback delay line. Compared to other works, the proposed design features a flexible spectrum temporal sequence, high scalability for multichannel spectrum sniffing, simplified design topology, and large group delay with relatively low transmission loss. To validate the design concept, a prototype is designed and measured, and both time-domain and frequency-domain verification are carried to demonstrate spectrum sniffing characteristic.","PeriodicalId":73297,"journal":{"name":"IEEE microwave and wireless technology letters","volume":"35 8","pages":"1166-1169"},"PeriodicalIF":3.4,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Patrick Boe;Dominik Brouczek;Lisa Mikiss;Marc Hofbauer;Daniel Miek;Michael Höft
{"title":"Compact Ku-Band Diplexer With Additive Manufactured Multimaterial Dielectric Resonator Insets","authors":"Patrick Boe;Dominik Brouczek;Lisa Mikiss;Marc Hofbauer;Daniel Miek;Michael Höft","doi":"10.1109/LMWT.2025.3562691","DOIUrl":"https://doi.org/10.1109/LMWT.2025.3562691","url":null,"abstract":"This letter presents the design and electrical measurement results of a novel compact diplexer design in Ku-band. The proposed diplexer is based on <inline-formula> <tex-math>$text {TM}_{01delta }$ </tex-math></inline-formula> mode dielectric resonators (DRs). A fourth-order filter with one triplet section for each channel is used. An additively manufactured inset is used for each filter, which contains the resonators and the required support structure and is printed from two materials in one piece. The chosen arrangement enables a compact design and simple assembly. To validate the concept, the design, fabrication, and measurement of the fourth-order dielectric diplexer are presented.","PeriodicalId":73297,"journal":{"name":"IEEE microwave and wireless technology letters","volume":"35 6","pages":"800-803"},"PeriodicalIF":0.0,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144299262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zexin Su;Chang Liu;Xuan Zhang;Qian Luo;Liu Wang;Sheng Hu;Xiao Ma;Bo Li
{"title":"A 38-GHz Differential Transimpedance Amplifier With Unbalanced Neutralizing Technique","authors":"Zexin Su;Chang Liu;Xuan Zhang;Qian Luo;Liu Wang;Sheng Hu;Xiao Ma;Bo Li","doi":"10.1109/LMWT.2025.3561787","DOIUrl":"https://doi.org/10.1109/LMWT.2025.3561787","url":null,"abstract":"In this letter, a broadband, low-noise and low-mismatch differential transimpedance amplifier (TIA) is proposed. In the classical single-ended-to-differential (S2D) strategy of TIA for mismatch reduction, the strong path and the weak path compensate each other, which results in low mismatch output differential signals. However, due to the different input strength of the strong and weak signals but the same gains of amplifier’s differential branches, mismatches could not eliminate well. To address this problem, an unbalanced neutralizing technique (UNT) is proposed. A single-sided negative capacitance feedback capacitor is introduced to strengthen the weak-side signal. Additionally, the design employs a combination of the high-gain input-stage and gain peaking in the subsequent stage to achieve improved bandwidth and noise performance simultaneously. Fabricated by 28-nm CMOS process, the chip achieves a transimpedance (TI) gain of 66.4 dB<inline-formula> <tex-math>$Omega $ </tex-math></inline-formula> across a 3-dB bandwidth of 38.8 GHz. The power consumption is 49 mW (including buffer). The averaged input-referred current noise density is 16.3 pA/<inline-formula> <tex-math>$sqrt {mathrm {Hz}}$ </tex-math></inline-formula>. The total active area of the chip is 0.08 mm<sup>2</sup>.","PeriodicalId":73297,"journal":{"name":"IEEE microwave and wireless technology letters","volume":"35 8","pages":"1218-1221"},"PeriodicalIF":3.4,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}