相控阵用BST薄膜移相器的结构设计与仿真
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摘要
高精度低损耗薄膜移相器不仅可以显著改善相控阵雷达系统的性能,而且能大大降低系统成本。钛酸锶钡(BST)薄膜因其具有高的介电调谐量、相对低的损耗和快的开关速度,在微波移相器制备中具有明显优势。
在分析研究目前常用的几种薄膜介质移相器结构与特性的基础上,本文选用分布式电容负载型BST薄膜移相器结构为研究对象。电容负载型BST薄膜移相器由高阻传输线和周期性负载的钛酸锶钡薄膜电容构成,其中的高阻传输线为共面波导。通过对共面波导BST薄膜移相器的理论分析并结合自身工艺条件和生产成本,本文选择负载电容为叉指电容结构,用电磁仿真软件Agilent ADS 2005A对叉指电容结构参数进行模拟,分别考察叉指电容的各个结构参数对移相单元反射系数、插入损耗和移相度的影响,选择综合性能最优的参数。然后在传统的叉指结构的基础上,对其进行改进,用ADS软件设计出移相器版图,并对移相器整体性能用计算机模拟,得了较好的结果,其反射系数低于-9dB,插入损耗小于0.9dB,相移接近330o。
The wide application and rapid development of phased array radar make phase shifter become the focus of research, which is the key component of phased array radar. Low loss and low cost microwave phase shifters are required to improve performance and reduce the cost of phase array. BaSrTiO3 (BST) thin films have great predominance in microwave phase shifter circuit applications because of their high tunable, relatively low loss, and fast switching speed.
After the analysis of some structures commonly used in dielectric phase shifter, a structure named distributed capacitor-loaded phase shifter was carried out. It is comprised of a high-impedance transmission line periodically loaded with BST thin film capacitors, which is called coplanar wave-guide (CPW). After the analysis of CPW BST thin film phase shifter, the fabrication technology and the cost, the interdigital capacitor was used as the loaded capacitor. Based on the model, the parameters was simulated in Agilent ADS 2005A, and then its structure parameter in influencing the reflectance, insert loss and the phase shift of the phase shifter were considered, and an optimized parameter of the structure was chosen. Finally the structure parameters of interdigital capacitors were improved, based on the traditional one, and the layout was designed using ADS. The whole performances of this phase shifter were simulated by computer, and acquired a better result. The reflectance is lower than -9dB, the insert loss is lower than 0.9dB, and the phase shift is nearly 330o.
在分析研究目前常用的几种薄膜介质移相器结构与特性的基础上,本文选用分布式电容负载型BST薄膜移相器结构为研究对象。电容负载型BST薄膜移相器由高阻传输线和周期性负载的钛酸锶钡薄膜电容构成,其中的高阻传输线为共面波导。通过对共面波导BST薄膜移相器的理论分析并结合自身工艺条件和生产成本,本文选择负载电容为叉指电容结构,用电磁仿真软件Agilent ADS 2005A对叉指电容结构参数进行模拟,分别考察叉指电容的各个结构参数对移相单元反射系数、插入损耗和移相度的影响,选择综合性能最优的参数。然后在传统的叉指结构的基础上,对其进行改进,用ADS软件设计出移相器版图,并对移相器整体性能用计算机模拟,得了较好的结果,其反射系数低于-9dB,插入损耗小于0.9dB,相移接近330o。
The wide application and rapid development of phased array radar make phase shifter become the focus of research, which is the key component of phased array radar. Low loss and low cost microwave phase shifters are required to improve performance and reduce the cost of phase array. BaSrTiO3 (BST) thin films have great predominance in microwave phase shifter circuit applications because of their high tunable, relatively low loss, and fast switching speed.
After the analysis of some structures commonly used in dielectric phase shifter, a structure named distributed capacitor-loaded phase shifter was carried out. It is comprised of a high-impedance transmission line periodically loaded with BST thin film capacitors, which is called coplanar wave-guide (CPW). After the analysis of CPW BST thin film phase shifter, the fabrication technology and the cost, the interdigital capacitor was used as the loaded capacitor. Based on the model, the parameters was simulated in Agilent ADS 2005A, and then its structure parameter in influencing the reflectance, insert loss and the phase shift of the phase shifter were considered, and an optimized parameter of the structure was chosen. Finally the structure parameters of interdigital capacitors were improved, based on the traditional one, and the layout was designed using ADS. The whole performances of this phase shifter were simulated by computer, and acquired a better result. The reflectance is lower than -9dB, the insert loss is lower than 0.9dB, and the phase shift is nearly 330o.
引文
[1]张光义.相控阵雷达系统.北京:国防工业出版社, 1994: 60～120
[2]丁鹭飞.雷达原理.西安:西北电讯工程学院出版社, 2004: 25～80
[3]余慧春,徐爱兰,惠春. BST薄膜铁电移相器研究进展.电子元件与材料, 2005, 24(3): 59~62
[4]徐爱东,陈海蓉.数字式矢量移相器.半导体情报, 1998, 35(4): 25～28
[5]张华娣,赵国庆.数字式移相器移频性能的分析.电子科技, 2004, 7: 50～57
[6]邵雯雯,惠春,徐爱兰. BST-MEMS移相器开关.电子元件与材料, 2004, 23(10): 20～26
[7]朱健,周百令,林金庭.开关线型四位数字MEMS移相器.固体电子学研究进展, 2005, 25(3): 344～348
[8] Barker N S, Rebeiz G M. Distributed MEMS true-time delay phase shifters and wide-band switches. [J].IEEE Trans Microwave Theory Tech, 1998, 11(46): 1881～1889
[9] Hayden J S, Rebeiz G M. Very low-loss distributed X-band and Ka-band MEMS phase shifters using metal-air-metal capacitors. [J].IEEE Trans Microwave Theory Tech, 2003, 51(1): 309～314
[10] A.T. Findikoglu, Q.X. Jia, D.W. Reagor, et al. Electric Characteristics of Coplanar Waveguide Devices Incorporating Nonlinear Dielectric Thin Film of SrTiO3 and Sr0.5Ba0.5TiO3. Microwave and Optical Technology Letters, 1995, 9(6): 306～309
[11] Franco De Flaviis, N.G. Alexopoulos, Oscar M. Stafsudd. Planar Microwave Integrated Phase Shifter Design with High Purity Ferroelectric Material. IEEE Transaction on Microwave Theory and Techniques. 1997, 45(6): 963~969
[12] V.K. Varadan, D.K. Ghodgaonkar, V.V Varadan.Ceramic. Phase Shifters for Electronically Steerable Antenna System. Microwave Journal, 1992.1: 18~25
[13] Richard W.Babbitt, Thomas E. Koscica, William C. Drach. Planar Microwave Electro-Optic Phase Shifter. Microwave Journal, 1992. 6: 63～78
[14] R.York, A. Nagra, E.Erker, et al. Microwave Integrated Circuits Using Thin-Film BST. IEEE MTT-S Digest, 2001, 36: 189~192
[15] A.Kozyrev, V.Osadchy, A.Pavlov, et al. Application of Ferroelectrics in Phase Shifter Design. IEEE MTT-S Digest, 2000, 35: 1355~1358
[16] Baki Acikel, Yu Liu, et al. Phase Shifters Using (Ba,Sr)TiO3 Thin Films on Sapphire and Glass Substrates, IEEE MTT-S Digest, 2001, 33: 1191～1194
[17] Erich G. Erker, Amit S. Nagra, Yu Liu, et al. Monolithic Ka-Band Phase Shifter Using Voltage Tunable BaSrTiO3 Parallel Plate Capacitors. IEEE Microwave and Guided Wave Letters, 2000, 10(1): 1169~1178
[18] Amit S. Nagra, Robert A.York. Investigation of BST for Millimeter-wave Applications. IEEE Microwave and Guided Wave Letters, 2001,11(12): 1123~1156
[19] Yu Liu, Amit S. Nagra, Erich G. Erker, et al. BaSrTiO3 Interdigitated Capacitors for Distributed Phase Shifter Applications. IEEE Microwave and Guided Wave Letters, 2000, 10(11): 125~136
[20] Yu Liu, Troy R. Taylor, Peter J, et al. High-performance and Low-cost Distributed Phase Shifters Using Optimized BaSrTiO3 Interdigitated Capacitors. IEEE Microwave and Guided Wave Letters, 2002, 12(15): 36~42
[21] R. Isom, M. Hawkins. Comparative evaluation of MEMS and ferroelectric Technologies in phase shifter design, IEEE Antennas and Propagation Society International Symposium, 2000, 2: 808~811
[22] J. B. L. Rao, G. V Trunk. Two low-cost phased arrays. IEEE AES system magazine, 1997, 6: 39~44
[23] J. B. L. Rao, D. P. Patel. Voltage-controlled Ferroelectric lens phased arrays. IEEE Transactions on antennas and propagation, 1999, 47(9): 458~468
[24] Peng Thian Teo, K. A. Jose. Adaptive ferroelectric phased shifters for phased arrayantenna. High Performance Electron Devices for Microwave and Optoelectronic Applications, 1999, 9:182~187.
[25] J. M. Pond, S. W. Kirchoefer. Ferroelectric thin films on ferrites for tunable microwave device application. Applications of Ferroelectrics, 2000, 1: 205~208
[26] Franco De Flaviis. Full wave analysis of coplanar phase shifter printed on high purity ferroelectric material. IEEE MTT-S Diges, 2000, 1: 1367~1370
[27] A. Kozyrev, V. Osadchy. Application of ferroelectric in phase shifter design. IEEE MTT-S Digest, 2000, 3: 1355-1358
[28] C.weil, P. wang. Tunable coplanar waveguide phase shifter using ferroelectric thick films. IEEE MTT-S Digest, 2003, 6: 1211-1220
[29] F. W. Van Keuls, C. H. Mueller. Room temperature thin film Ku-band coupled microstrip phase shifter: effects of film thickness, doping, annealing and substrate choice, IEEE MTT-S Digest, 1999, 6: 737~740
[30] R. Romanofsky, J. Bernhard. a K-band linear phased array antenna based on Ba0.60Sr0.40TiO3 thin film phase shifters, IEEE MTT-S Digest, 2000, 3: 1351~1354
[31]范寿康.微波技术与微波电路.北京:机械工业出版社, 2003: 9~44
[32]水启刚.微波技术.北京:国防工业出版社, 2005: 25~126
[33]苏志彬,曹桂兴.一种新颖的数字移相电路.空间电子技术, 2004, Vol. 1: 33~36
[34] Jaemo Im, A ucillo O, Baumann P K. Composition-control of magnetron-sputter-deposited (Ba1-xSrx)TiO3 thin films for voltage tunable devices. [J].Appl Phys Letter, 2000, 76: 625~627
[35] Kim W J, Chang W, Q adri S B, et al. Microwave properties of tetragonally distorted (Ba0.5Sr0.5)TiO3 thin films. [J]. Appl Phys Letter, 2000, 76: 1185~1187
[36] Ding Y P, Jin C Y, Meng Z Y. Investigation on the amo rphous-crystalline transition and micro structure of sol-gel derived (Ba1-xSrx)TiO3 thin film. [J]. Mater Res Bulletin, 2000, 35: 1187~1193
[37] Robert R. Romanofsky, Jennifer T. Bernhard, Frederick W. Van Keuls. K-BandPhased Array Antennas Based on Ba0.60Sr0.40TiO3 Thin film Phase Shifters. IEEE Transactions on Microwave Theory and Techniques, 2000, Vol. 48, No.12: 2504~2510
[38] Dongsu Kim, Sang-Soo Je, J. Stevenson Kenney. Design of Ferroelectric Phase Shifter for Minimum Performance Variation over Temperature. IEEE MTT-S Digest, 2004, 5: 257~260
[39] F.W. Van Keuls, C. H. Mueller, F.A. Miranda, et al. Room Temperature Thin Film BaxSr1-xTiO3 Ku-Band Coupled Microstrip Phase Shifters, IEEE MTT-S Digest, 1999, 4: 737~740
[40] Peng Thian Teo, K.A. Jose, Y.B. Gan. Adaptive Ferroelectric Phased Shifters for Phased Array Antenna. IEEE MTT-S Digest, 1999, 2: 182~187
[41] Carl H. Mueller, Robert R. Romanofsky. Ferroelectric thin film and broadband satellite systems, IEEE Potentials, 2001, 5: 36~39
[42] M.J. Lancaster, J. Powell, A. Porch. Thin Film Ferroelectric Microwave Devices. Supercond. Sci. Technol, 1998,6: 1323~1334
[43] F.W. Van Keuis, R.R. Romanofsky, D.Y. Bohman, et al. Thin Film Conductor/Ferroelectric Coupled Microstripline Phase Shifters for Phased Array Applications. 1997, Appl. Phys. Letter. 71(21): 3075~3077
[44] Baki Acikel, Troy R. Taylor, Peter J. Hansen. A New High Performance Phase Shifter using BaxSr1-xTiO3 Thin Films. IEEE Microwave and Wireless Components Letter, 2002,12(7): 36~50
[45] Baki Acikel, Troy R. Taylor, Peter J. Hansen. A New X Band 180o High Performance Phase Shifter using (Ba,Sr)TiO3 Thin Films. IEEE MTT-S Digest, 2002, 4: 1467~1469
[46] Amit S. Nagar, Robert A. York. Distributed Analog Phase Shifters with Low Insertion loss. IEEE Transaction on Microwave Theory and Techniques, 1999,47(9): 1705~1711
[47] Amit S. Nagra, Jian Xu, Erich Erker, et al. Monolithic GaAs Phase Shifter Circuit with low Insertion loss and continuous 0~360o Phase Shift at 20GHz. IEEE Microwave and Guided Wave Letters, 1999, 9(1): 306~325
[48] Erich G. Erker, Amit S. Nagra, Yu Liu, et al. Monolithic Ka-Band Phase Shifter Using Voltage Tunable BaSrTiO3 Parallel Plate Capacitors. IEEE Microwave and Guided Wave Letters, 2000, 10(1): 10~12
[49] Yu Liu, Amit S. Nagra, Erich G. Erker, et al. BaSrTiO3 Interdigitated Capacitors for Distributed Phase Shifter Applications. IEEE Microwave and Guided Wave Letters, 2000, 10(11): 1125~1160
[50] Taeksoo Ji, Hargsoon Yoon, Jose K. Abraham. Ku-Band Antenna Array Feed Distribution Network with Ferroelectric Phase Shifter on Silicon. IEEE Transaction on Microwave Theory and Techniques, 2006, 54(3): 1131~1138
[51] G. Velu, K. Blary, L. Burgnies, J.C. Carru. A 310o/3.6-dB K-Band Phase Shifter using Paraelectric BST Thin Films. IEEE Microwave and Wireless Components Letters, 2006, 16(2): 87~89
[52] Qingduan Meng, Xueqiang Zhang, Fei Li. An Impedance Matched Phase Shifter using BaSrTiO3 Thin Film. IEEE Microwave and Wireless Components Letters, 2006, 16(6): 345~347
[2]丁鹭飞.雷达原理.西安:西北电讯工程学院出版社, 2004: 25～80
[3]余慧春,徐爱兰,惠春. BST薄膜铁电移相器研究进展.电子元件与材料, 2005, 24(3): 59~62
[4]徐爱东,陈海蓉.数字式矢量移相器.半导体情报, 1998, 35(4): 25～28
[5]张华娣,赵国庆.数字式移相器移频性能的分析.电子科技, 2004, 7: 50～57
[6]邵雯雯,惠春,徐爱兰. BST-MEMS移相器开关.电子元件与材料, 2004, 23(10): 20～26
[7]朱健,周百令,林金庭.开关线型四位数字MEMS移相器.固体电子学研究进展, 2005, 25(3): 344～348
[8] Barker N S, Rebeiz G M. Distributed MEMS true-time delay phase shifters and wide-band switches. [J].IEEE Trans Microwave Theory Tech, 1998, 11(46): 1881～1889
[9] Hayden J S, Rebeiz G M. Very low-loss distributed X-band and Ka-band MEMS phase shifters using metal-air-metal capacitors. [J].IEEE Trans Microwave Theory Tech, 2003, 51(1): 309～314
[10] A.T. Findikoglu, Q.X. Jia, D.W. Reagor, et al. Electric Characteristics of Coplanar Waveguide Devices Incorporating Nonlinear Dielectric Thin Film of SrTiO3 and Sr0.5Ba0.5TiO3. Microwave and Optical Technology Letters, 1995, 9(6): 306～309
[11] Franco De Flaviis, N.G. Alexopoulos, Oscar M. Stafsudd. Planar Microwave Integrated Phase Shifter Design with High Purity Ferroelectric Material. IEEE Transaction on Microwave Theory and Techniques. 1997, 45(6): 963~969
[12] V.K. Varadan, D.K. Ghodgaonkar, V.V Varadan.Ceramic. Phase Shifters for Electronically Steerable Antenna System. Microwave Journal, 1992.1: 18~25
[13] Richard W.Babbitt, Thomas E. Koscica, William C. Drach. Planar Microwave Electro-Optic Phase Shifter. Microwave Journal, 1992. 6: 63～78
[14] R.York, A. Nagra, E.Erker, et al. Microwave Integrated Circuits Using Thin-Film BST. IEEE MTT-S Digest, 2001, 36: 189~192
[15] A.Kozyrev, V.Osadchy, A.Pavlov, et al. Application of Ferroelectrics in Phase Shifter Design. IEEE MTT-S Digest, 2000, 35: 1355~1358
[16] Baki Acikel, Yu Liu, et al. Phase Shifters Using (Ba,Sr)TiO3 Thin Films on Sapphire and Glass Substrates, IEEE MTT-S Digest, 2001, 33: 1191～1194
[17] Erich G. Erker, Amit S. Nagra, Yu Liu, et al. Monolithic Ka-Band Phase Shifter Using Voltage Tunable BaSrTiO3 Parallel Plate Capacitors. IEEE Microwave and Guided Wave Letters, 2000, 10(1): 1169~1178
[18] Amit S. Nagra, Robert A.York. Investigation of BST for Millimeter-wave Applications. IEEE Microwave and Guided Wave Letters, 2001,11(12): 1123~1156
[19] Yu Liu, Amit S. Nagra, Erich G. Erker, et al. BaSrTiO3 Interdigitated Capacitors for Distributed Phase Shifter Applications. IEEE Microwave and Guided Wave Letters, 2000, 10(11): 125~136
[20] Yu Liu, Troy R. Taylor, Peter J, et al. High-performance and Low-cost Distributed Phase Shifters Using Optimized BaSrTiO3 Interdigitated Capacitors. IEEE Microwave and Guided Wave Letters, 2002, 12(15): 36~42
[21] R. Isom, M. Hawkins. Comparative evaluation of MEMS and ferroelectric Technologies in phase shifter design, IEEE Antennas and Propagation Society International Symposium, 2000, 2: 808~811
[22] J. B. L. Rao, G. V Trunk. Two low-cost phased arrays. IEEE AES system magazine, 1997, 6: 39~44
[23] J. B. L. Rao, D. P. Patel. Voltage-controlled Ferroelectric lens phased arrays. IEEE Transactions on antennas and propagation, 1999, 47(9): 458~468
[24] Peng Thian Teo, K. A. Jose. Adaptive ferroelectric phased shifters for phased arrayantenna. High Performance Electron Devices for Microwave and Optoelectronic Applications, 1999, 9:182~187.
[25] J. M. Pond, S. W. Kirchoefer. Ferroelectric thin films on ferrites for tunable microwave device application. Applications of Ferroelectrics, 2000, 1: 205~208
[26] Franco De Flaviis. Full wave analysis of coplanar phase shifter printed on high purity ferroelectric material. IEEE MTT-S Diges, 2000, 1: 1367~1370
[27] A. Kozyrev, V. Osadchy. Application of ferroelectric in phase shifter design. IEEE MTT-S Digest, 2000, 3: 1355-1358
[28] C.weil, P. wang. Tunable coplanar waveguide phase shifter using ferroelectric thick films. IEEE MTT-S Digest, 2003, 6: 1211-1220
[29] F. W. Van Keuls, C. H. Mueller. Room temperature thin film Ku-band coupled microstrip phase shifter: effects of film thickness, doping, annealing and substrate choice, IEEE MTT-S Digest, 1999, 6: 737~740
[30] R. Romanofsky, J. Bernhard. a K-band linear phased array antenna based on Ba0.60Sr0.40TiO3 thin film phase shifters, IEEE MTT-S Digest, 2000, 3: 1351~1354
[31]范寿康.微波技术与微波电路.北京:机械工业出版社, 2003: 9~44
[32]水启刚.微波技术.北京:国防工业出版社, 2005: 25~126
[33]苏志彬,曹桂兴.一种新颖的数字移相电路.空间电子技术, 2004, Vol. 1: 33~36
[34] Jaemo Im, A ucillo O, Baumann P K. Composition-control of magnetron-sputter-deposited (Ba1-xSrx)TiO3 thin films for voltage tunable devices. [J].Appl Phys Letter, 2000, 76: 625~627
[35] Kim W J, Chang W, Q adri S B, et al. Microwave properties of tetragonally distorted (Ba0.5Sr0.5)TiO3 thin films. [J]. Appl Phys Letter, 2000, 76: 1185~1187
[36] Ding Y P, Jin C Y, Meng Z Y. Investigation on the amo rphous-crystalline transition and micro structure of sol-gel derived (Ba1-xSrx)TiO3 thin film. [J]. Mater Res Bulletin, 2000, 35: 1187~1193
[37] Robert R. Romanofsky, Jennifer T. Bernhard, Frederick W. Van Keuls. K-BandPhased Array Antennas Based on Ba0.60Sr0.40TiO3 Thin film Phase Shifters. IEEE Transactions on Microwave Theory and Techniques, 2000, Vol. 48, No.12: 2504~2510
[38] Dongsu Kim, Sang-Soo Je, J. Stevenson Kenney. Design of Ferroelectric Phase Shifter for Minimum Performance Variation over Temperature. IEEE MTT-S Digest, 2004, 5: 257~260
[39] F.W. Van Keuls, C. H. Mueller, F.A. Miranda, et al. Room Temperature Thin Film BaxSr1-xTiO3 Ku-Band Coupled Microstrip Phase Shifters, IEEE MTT-S Digest, 1999, 4: 737~740
[40] Peng Thian Teo, K.A. Jose, Y.B. Gan. Adaptive Ferroelectric Phased Shifters for Phased Array Antenna. IEEE MTT-S Digest, 1999, 2: 182~187
[41] Carl H. Mueller, Robert R. Romanofsky. Ferroelectric thin film and broadband satellite systems, IEEE Potentials, 2001, 5: 36~39
[42] M.J. Lancaster, J. Powell, A. Porch. Thin Film Ferroelectric Microwave Devices. Supercond. Sci. Technol, 1998,6: 1323~1334
[43] F.W. Van Keuis, R.R. Romanofsky, D.Y. Bohman, et al. Thin Film Conductor/Ferroelectric Coupled Microstripline Phase Shifters for Phased Array Applications. 1997, Appl. Phys. Letter. 71(21): 3075~3077
[44] Baki Acikel, Troy R. Taylor, Peter J. Hansen. A New High Performance Phase Shifter using BaxSr1-xTiO3 Thin Films. IEEE Microwave and Wireless Components Letter, 2002,12(7): 36~50
[45] Baki Acikel, Troy R. Taylor, Peter J. Hansen. A New X Band 180o High Performance Phase Shifter using (Ba,Sr)TiO3 Thin Films. IEEE MTT-S Digest, 2002, 4: 1467~1469
[46] Amit S. Nagar, Robert A. York. Distributed Analog Phase Shifters with Low Insertion loss. IEEE Transaction on Microwave Theory and Techniques, 1999,47(9): 1705~1711
[47] Amit S. Nagra, Jian Xu, Erich Erker, et al. Monolithic GaAs Phase Shifter Circuit with low Insertion loss and continuous 0~360o Phase Shift at 20GHz. IEEE Microwave and Guided Wave Letters, 1999, 9(1): 306~325
[48] Erich G. Erker, Amit S. Nagra, Yu Liu, et al. Monolithic Ka-Band Phase Shifter Using Voltage Tunable BaSrTiO3 Parallel Plate Capacitors. IEEE Microwave and Guided Wave Letters, 2000, 10(1): 10~12
[49] Yu Liu, Amit S. Nagra, Erich G. Erker, et al. BaSrTiO3 Interdigitated Capacitors for Distributed Phase Shifter Applications. IEEE Microwave and Guided Wave Letters, 2000, 10(11): 1125~1160
[50] Taeksoo Ji, Hargsoon Yoon, Jose K. Abraham. Ku-Band Antenna Array Feed Distribution Network with Ferroelectric Phase Shifter on Silicon. IEEE Transaction on Microwave Theory and Techniques, 2006, 54(3): 1131~1138
[51] G. Velu, K. Blary, L. Burgnies, J.C. Carru. A 310o/3.6-dB K-Band Phase Shifter using Paraelectric BST Thin Films. IEEE Microwave and Wireless Components Letters, 2006, 16(2): 87~89
[52] Qingduan Meng, Xueqiang Zhang, Fei Li. An Impedance Matched Phase Shifter using BaSrTiO3 Thin Film. IEEE Microwave and Wireless Components Letters, 2006, 16(6): 345~347