360°低插损小型化反射式移相器设计

针对第5代移动通信大规模多输入多输出(massive MIMO)和无线回传系统中移相阵列的应用需求,本文对反射式移相器(RTPS)的模型拓扑进行了对比分析,提出了四元件双可调(FEDA)负载拓扑的设计方法和相位变换的调整方式,研究了移相步进和插入损耗的影响因素,采用数字变容管(DTC)进行RTPS的调谐设计。实验结果表明,在4.4～5.0 GHz全频段范围内实测移相范围大于360°,移相步进小于12°,插入损耗小于1.8 dB,尺寸仅为10 mm×8 mm,兼具低插损、小型化、大带宽、高精度、易控制等优点。     

Ferroelectric phase shifters and their performance in microwave phased array antennas

Abstract

Recent advances in the development of Barium Strontium Titanate ferroelectric composition has made possible reasonable performance of ferroeletric phase shifters to frequencies up to 10 GHz. These material improvements, coupled with phase shifter circuit design changes have resulted in phase shifts greater than 360 degrees with less than 6 dB insertion loss. In particular additives to the BaxSr1-_xTiO₃ composition have been shown to exhibit a consistent electrical phase shift verses DC potential over parameters of temperature and humidity. These ferroelectric material improvements and circuit design changes, included with the development of multiple ferroelectric phase shifters makes possible the fabrication of a low cost electronic scanning antenna. A single four element phase shifter was used with a one dimensional linear antenna array which was constructed on three layers and used an aperture coupled distribution technique. Individual elements of this multiple four element phase shifter were evaluated with respect to uniformity phase shift and insertion loss. The four element antenna was fed by four ferroelectric phase shifters and the phase shifters are corporately fed by the microwave source. The ferroelectric phase shifters are controlled via a dedicated microcontroller which calibrates out element phase variations and provides a real time scan capability for the antenna assembly.     

Microwave Performance of Distributed Analog Phase Shifter Using Ferroelectric (Ba,Sr)TiO3 Thin Films

This work presents the design, fabrication and microwave performance of distributed analog phase shifter (DAPS) fabricated on (Ba,Sr)TiO₃ (BST) thin films for X-band applications. Ferroelectric BST thin films were deposited on MgO substrates by pulsed laser deposition. The DAPS consists of high impedance coplanar waveguide (CPW) and periodically loaded tunable BST interdigitated capacitors (IDC). In order to reduce the insertion loss of DAPS and to remove the alteration of unloaded CPW properties according to an applied dc bias voltage, BST layer under transmission lines were removed by photolithography and RF-ion milling. The measured results are in good agreement with the simulated results at the frequencies of interest. The measured differential phase shift based on BST thin films was 24° and the insertion loss decreased from ?1.1 dB to ?0.7 dB with increasing the bias voltage from 0 to 40 V at 10 GHz.     

Reflection-Type Ferroelectric Phase Shifter With Defected Ground Structure

In order to obtain a low-loss ferroelectric phase shifter, we were designed and fabricated the reflection-type ferroelectric phase shifter with the defected ground structure (DGS) resonators. The ferroelectric phase shifter is consisted of a 3-dB 90° branch-line hybrid coupler and terminated reflective circuit with tunable ferroelectric DGS resonator which can provide a high Q resonator characteristic at high frequencies. The design parameters of equivalent circuit for the tunable DGS resonator are derived by circuit analysis method and three-dimensional full wave finite element method. At 13.5 GHz, the fabricated phase shifter exhibited an insertion loss of better than 3.4 dB.     

Microwave Properties of Mn Doped (Ba1 - x,Srx)TiO3Thin Films for Tunable Phase Shifter

Ferroelectric Mn doped Ba_0.5Sr_0.5TiO₃ (Mn-BST) films with/without BaTiO₃ (BT) buffer layer have been grown on (001) MgO substrates by a pulsed laser deposition to investigate electrical tunability at microwave frequencies. Structural properties and surface morphologies of the films were investigated using an X-ray diffractometer and a scanning electron microscope, respectively. Microwave dielectric properties of Mn-BST thin films with BT buffer were studied for reduction of dielectric loss and improvement of electrical tunability. Distributed analog phase shifters have been designed and fabricated on Mn-BST films with/without BT buffer layer to understand microwave dielectric properties. The differential phase shift of the phase shifter fabricated on Mn-BST film was 22° at 10 GHz with 80 V of applied dc bias voltage. In comparison, phase shifter fabricated on Mn-BST/BT multilayers exhibit 41° of differential phase shift at the same condition. This suggests that a BT buffer layer is for microwave tunable device applications. The phase shifter fabricated on Mn-BST/BT multilayers exhibit a low insertion loss (S₂₁) of ?1.1 dB, and a low return loss (S₁₁) of ?14 dB with a bias voltage of 80 V.     

Millimeter-Wave Loaded Line Ferroelectric Phase Shifters

Ferroelectric loaded line phase shifters operating at millimeter waves for phased array antenna applications are presented. Phase shifters were manufactured on using Ba_0.3Sr_0.7TiO₃ thin films. The magnetron sputtering process was used to fabricate these Ba_0.3Sr_0.7TiO₃ ferroelectric films with a thickness ～1 μm. The phase shifter operating at V-band (60 GHz) demonstrated continuous phase shift up to 220 deg and figure of merit (FOM) 22 deg/dB. The phase shifter operating at Ka-band (30 GHz) showed phase shift up to 360 deg and FOM 40 deg/dB.     

Microwave Tunable Components and Subsystems Based on Ferroelectrics: Physics and Principles of Design

The most promising microwave ferroelecric device is a ferroelectric phase shifter, aimed to be an element of a phased-array antenna. The following characteristics of the phase shifter are important: microwave insertion loss, range of operational temperatures, life time. Designing microwave tunable components is based on carefully developed models of ferroelectrics and appropriate software of the circuit design. The quality of a phase shifter is determined by the figure of merit ( F ) defined as a ratio phase shift/insertion loss and measured in deg/dB. For competitive applications one needs F = 200-300 deg/dB. An extended temperature range of operation is urgently required. There are the following ways of improvement of the ferroelectric phase shifters: i) utilizing an appropriate chemical compound of ferroelectric material, ii) developing the structure of the device, for example, the film with a variable composition factor, iii) application of the digital mode of operation.     

CHARACTERIZATION OF FERROELECTRIC FILMS UP TO 60 Ghz: APPLICATION TO PHASE SHIFTERS

ABSTRACT

Paraelectric Ba_0.5Sr_0.5TiO₃ films 0.3 μm thick have been deposited by sol-gel on c-axis sapphire substrates. They have been investigated from 1 kHz to 60 GHz using coplanar waveguide transmission lines and interdigitated capacitors. The dielectric constant ε_r is around 300 and the loss tangent is 0.16 at 50 GHz. The tunability is constant with frequency with a mean value of 42%. Analog phase shifters were subsequently fabricated. A 180° phase shift was obtained at 60 GHz with a 17 V bias. The maximum value of phase shift per decibel of insertion losses (at 0 V) is 13°/dB at 30 GHz with a bias of 30 V.     

Broadband phase shifter combining high temperature superconductors and ferroelectric thin films

Abstract

A broadband CPW phase shifter combining the low loss of high temperature superconductors and the variable dielectric constant of ferroelectrics is described. A phase shift of 80 degrees at 10 GHz with a 30 V bias has been demonstrated. A quasistastic filling factor model has been compared to more sophisticated techniques with excellent agreement.     

Evaluation of Chemical Solution Deposited Ba x Sr 1−x TiO 3 Thin Films on LaAlO 3 in Tunable Microwave Devices

Epitaxial Ba x Sr 1 m x TiO 3 (BST) films grown on LaAlO 3 by several deposition methods have been tested in coupled microstrip phase shifters (CMPS) at frequencies from 10 to 24 GHz. To date the best performance for the devices has been achieved using Pulsed Laser Deposition (PLD). However, recently chemical solution deposition (CSD) methods such as sol-gel and Metal-Organic Chemical Liquid Deposition (MOCLD) have shown advances in fabricating BST films for tunable microwave applications. CSD processes promise improvements in cost, speed and area covered during BST film deposition. This paper compares over 35 BST films used in identical CMPS circuits. In this study, the highest measured figures of merit of phase shift per dB of loss for PLD, MOCLD and sol-gel CMPS are 49, 47 and 41°/dB respectively. While other phase shifter designs using BST films have surpassed these values, these data base of identical circuits allows us to compare the BST films. X-ray diffraction characterization for many of the BST films is also given.     

A low-loss compact six-bit DMTL phase shifter for phased array antenna applications

A phase shifter is one of the main components of radars and phased array systems. In this paper, a novel three-state two-bridge unit cell is presented for a compact low-loss six-bit distributed microelectromechanical systems (MEMS) transmission line (DMTL) phase shifter. The proposed unit cell includes a coplanar waveguide (CPW) transmission line, a MEMS bridge on the signal line, two metal-air-metal (MAM) capacitors on a glass substrate, and two additional electrodes under the MEMS bridge, near the signal line. Using these electrodes, it is possible to generate two different phase states employing the MEMS bridge, and the third state is produced by a metal-air-metal (MAM) bridge. Hence, the designed structure can generate three different phase shifts per unit cell (i.e., 5.625°, 11.25°, and 22.5° phase shifts). The novelty of this design is that the number of unit cells is considerably reduced from 64 in a conventional six-bit phase shifter to only 17 in our design. Therefore, the total length of the six-bit phase shifter and average loss are considerably reduced. The designed structure is calculated and simulated at 32 GHz using MATLAB and ANSOFT HFSS, respectively. According to the calculation and simulation results, the lateral size of the phase shifter is only 8.5 mm, the root mean square (RMS) phase error is 1.38°, and the average loss is 1.1 dB. The feasibility of the proposed design is investigated using the proposed fabrication process. The designed phase shifter can be easily scaled to other frequencies for radar and satellite applications with more bits.     

Thin film BaxSr1-xTiO3 ku- and k-band phase shifters grown on MgO substrates

Abstract

We report measurements of gold circuits fabricated on four Ba_xSr_1-xTiO₃ ferroelectric films doped with 1% Mn grown on MgO substrates by laser ablation. Low frequency (1 MHz) measurements of σ_T and tanδ on interdigital capacitors are compared with high frequency measurements of phase shift and insertion loss on coupled microstrip phase shifters patterned onto the same films. The variation in temperature of both high and low frequency device parameters is compared. Annealed with amorphous buffer layer and unannealed films are compared. Room temperature figures of merit of phase shift per insertion loss of up to 58.4°/dB at 18 GHz and 400 V dc bias were measured.     

Compact Distributed Phase Shifters at X-Band Using BST

A new type of distributed analog phase shifter is presented that utilizes the coplanar strip transmission line topology. This transmission line has several benefits for phase shifter design, resulting in decreased physical dimensions and potentially lower losses. A prototype was constructed using thin-film barium strontium titante (BST) varactor technology. The design achieved a 49°/dB figure of merit at 10 GHz. The performance and chip area of the coplanar strip circuit are compared with designs using coplanar waveguide and synthetic lumped element transmission lines.     

Ka波段自偏置微带边导模隔离器仿真设计与性能

基于M型锶六角铁氧体的高各向异性场,采用HFSS软件设计了中心频率在28.2GHz的自偏置边导模隔离器。仿真结果表明,在28.2GHz附近,插入损耗为6dB,隔离度大于38dB,20dB以下隔离带宽约为3.5GHz。采用传统固相反应法制备SrM六角铁氧体材料基片并用丝网印刷工艺实现基片上的微带电路,根据设计的结构参数制备了自偏置边导模隔离器。测试结果表明,该自偏置隔离器在27~29GHz范围内,表现出强烈的非互易性,插入损耗小于10dB,最大隔离度大于45dB。由于不需要外加偏置磁场,器件实现了小型化,宽频带,仿真与实测吻合得较好。     

Novel nonmagnetic 30-dB traveling-wave single-sideband optical isolator integrated in III/V material

Various attempts have been made to fabricate waveguide-type isolators in III/V material by implanting magnetic materials, but none of them has so far resulted in a commercial product. Here, we report for first time on an integrated optical isolator implemented in III/V material. It consists of a single-sideband electrooptic modulator where traveling electrical waves make the transmission direction-dependent. Isolation is 30 dB, excess insertion loss is 8 dB. Residual rms ripple is 7% for peak-to-peak RF driving amplitudes of 3.5 V at 4.0 GHz. The estimated transmission penalty for 40 Gb/s return-to-zero differential phase shift keying (RZ-DPSK) signals is 0.2 dB (0 dB measured).     

Low-loss 7-bit S-band CMOS passive phase shifter with digital control

This paper presents the design and implementation of a 7-bit S-band digital passive phase shifter using Complementary Metal-Oxide-Semiconductor (CMOS) 65-nm technology in 2.6- to 3.2-GHz frequency band. New switched delay network topology has been used for 5.625° and 2.8°, and modified switched filter topology has been used for implementation of other phase bits to achieve 7-bit performance with low insertion loss and better isolation. The measured results of the fabricated chip show 7-bit performance with an average insertion loss of 11 dB, average root mean square (RMS) phase error of less than 2.0°, average RMS amplitude error of less than 0.6 dB, input matching (S₁₁) better than −7.5 dB, and output matching (S₂₂) better than −14.5 dB across the target frequency band at 50Ω input/output impedance.     

Ferroelectric lens phased array antenna: An update

Abstract

The ferroelectric lens is a new type of phased array antenna. It uniquely incorporates bulk phase shifting using bulk ferroelectric ceramics to reduce the cost of the phased array. This paper presents the latest X band (8-12 GHz) results with improved ferroelectrics; the loss due to these ferroelectrics is less than 2 dB for obtaining 360° differential phase shift at 10 GHz. The antenna pattern of an interferometer built with ferroelectrics and demonstrating electronic scanning at 10 GHz is presented. A brief review of the ferroelectric lens concept is also included.     

Highly Textured Chemical Solution Deposited Ba 0.5 Sr 0.5 Ti 1−x Mn x O 3 (x ∼⃒ 0 to 5 at %) Thin Films For Microwave Dielectric Applications

We have optimized the process methodology to grow highly (100) oriented barium strontium titanate (Ba x Sr 1 m x TiO 3 ) (x = 0.5 and 0.6) thin films on lattice-matched (100) lanthanum aluminate (LAO) substrates by sol-gel technique. These films exhibited excellent phase shift and insertion loss characteristics at microwave frequencies. The work has been extended to study the effect of manganese (Mn) doping on the nature of epitaxial growth and electrical behavior of (100) oriented Ba 0.5 Sr 0.5 TiO 3 (BST) thin films. The degree of texturing and quality of the in-plane epitaxy of BST thin films on lanthanum aluminate (LAO) was found to be improved for upto 3 at% Mn doping. These films were characterized in terms of their electrical properties and dielectric behavior at low (1kHz-1MHz) and microwave frequencies. We have fabricated eight-element coupled microstrip phase shifters (CMPS) and tested them in terms of their degree of phase shift and insertion loss characteristics. The phase shift increases from 239 ° (undoped) to 337 ° with 3 at% Mn doping. However, the insertion loss also increases (5.4 to 9.9 dB respectively) with the increase in dopant concentration so that effective s factor (defined as phase shift/insertion loss) does not improve significantly and remains in the range of 33-44 °/dB. The observed electrical properties are correlated with the structure and microstructure of the Mn doped BST films.     

一种新型的六位数字移相器的设计

针对传统的数字移相器插入损耗高和相位精度低等性能的不足,提出了一种新型的加匹配线的开关式移相器设计技术。包括固定长λ/2主线以及在主线边缘长λ/8的平行短路和开路短截线,克服了传统数字移相器设计中端口驻波比高,插入损耗大的缺点,而且在相位精度上也有提高。在设计中,用加匹配线的方法对45°,90°和180°移相器进行设计,并将相位为5.625°,11.25°,22.5°,45°,90°及180°6个二态移相器电路组合起来,构成六位数字式移相器,通过二进制代码控制各个PIN二极管,从而得到64个相移状态,实现了输出频率范围为400～450MHz的低插入损耗,高相移精度的六位数字移相器,通过实际测试得到整个六位数字移相器插入损耗低于5.3dB,相移精度小于3°,驻波比小于1.5的较好实验结果,具有比传统设计方法更优良性能。     

一种宽频带微带线垂直过渡结构设计

针对微波多层电路的微带线垂直过渡问题,提出了一种新型的、适用于毫米波频段的微带线垂直过渡结构,通过微带线上的补偿结构实现了匹配设计,使得微波信号在微波多层结构中跨层传输.该过渡电路结构具有信号传输损耗小、频带宽,易于加工的特性,在微波电路设计方面具有较高的实用价值.将该微带线垂直过渡结构在三维电磁场仿真软件中进行了建模,并进行了实物加工和测试.实物测试结果表明,在0.5～38 GHz的频带范围内插入损耗小于2.7 dB(含两个K-2.92 mm接头及微带传输线损耗),回波损耗大于9 dB.