Tunable Dual Band Filter with BST Capacitors

A tunable double band band-stop filter based on BST is presented. This configuration has a coplanar microstrip loaded with stepped impedance resonators. Ferroelectric BST parallel plate capacitors were loaded at the end of the stepped impedance resonators. When a DC voltage is applied to the BST capacitors, the change in capacitance shifts the resonance frequency of the stepped impedance transformers. The filters were designed with notch frequencies at 1.5 GHz and 3.5 GHz without loading them with BST capacitors. The filter circuits were simulated with Agilent ADS and were fabricated on FR-4 substrates. By loading the resonators with BST capacitors with no DC applied voltage, the first and second notch frequency shifts significantly. The first notch frequency can be tuned from 570 MHz to 781 MHz and the second notch frequency from 2.16 GHz to 2.55 GHz by applying the bias voltage of 5volts. The performance of the BST tuned filters were compared with filters tuned with p-n junction varactors.     

基于微带三模谐振器的超宽带带通滤波器设计

提出一种基于微带三模谐振器的超宽带带通滤波器设计.该滤波器由一个中心加载阶跃阻抗开路枝节的三模谐振器,及两组用于抑制谐波的新型哑铃型缺陷地结构组成.使用交指型馈电方式及在馈电处的地板开槽实现超宽带需要的的强耦合,利用缺陷地结构抑制高次谐波实现良好的阻带特性.仿真结果表明,所设计的滤波器通带3 dB相对带宽达到80％(4.06～9.48 GHz),通带内插入损耗小于0.58 dB,回波损耗大24 dB,通带外10 dB阻带覆盖到30 GHz,通带两侧附近均有一个传输零点,获得了陡峭的通带边缘,较好地实现了美国联邦通信委员会(FCC)授权的超宽带通信系统的频谱使用要求.该滤波器结构简单,谐振器自身尺寸小于中心频率下0.5λg×0.5λg.最小带线和最小缝隙宽度均不小于0.1 mm,易于低成本加工,具有较高的实用价值.     

High-quality coplanar waveguide tunable band-stop filter using defected ground structure and comb-line resonator with radio frequency microelectromechanical system varactors

A new analog tunable Ka-band band-stop filter is proposed on high resistivity silicon (HRS) substrate using radio frequency microelectromechanical systems (RF MEMS) varactors for satellite and radar applications. The designed filter uses a λ/4 comb-line resonator on the center line of a coplanar waveguide (CPW) with a new uncommon defected ground structure (DGS). Using the DGS in the proposed structure not only decreases the lateral size of the filter but also increases the quality factor. The tuning range of the proposed filter is 29.8–35.6 GHz with a maximum actuation voltage of 44.5 V and a band rejection between 37 and 45 dB. The quality factors of the designed filter in the up and down states of the MEMS varactors are 162 and 292, respectively. The equivalent circuit model of the filter is exactly extracted, and DGS dimensions are optimized. Based on the frequency simulation using ANSOFT HFSS 14, the insertion loss of the designed filter is about 0.51 dB in the 0–20 GHz range and 2 dB in the 0–15 GHz range in, respectively, up and down state of the bridge. The return losses are 0.51 and 0.33 dB at the center frequency for the up- and down-state configuration of the bridge. A step-by-step fabrication process is also proposed for designing the band-stop filter. High quality factor, small size, and improved structure are the advantages of the proposed design.     

A reconfigurable bandpass-bandstop filter based on varactor-loaded closed-ring resonators [Technical Committee]

In this article, a novel reconfigurable bandpass-bandstop filter based on the varactor-loaded closed-ring resonators is presented, where the bandpass and bandstop characteristics can be easily controlled by tuning the varactor bias voltage. This reconfigurability results from the perturbation effect on the degenerated even and odd modes of the closed-ring resonator. When the perturbation varactor is at the series resonance, its reactance vanishes, so a bandstop characteristic is formed. When the perturbation varactor is changed to be capacitive, the bandpass characteristic is generated. Additional varactors, incorporated at input and output ports, are tuned along with the perturbation varactors to maintain good return losses.     

Reconfigurable narrowband microwave band‐pass filter

A method is proposed for the design of band‐pass filters with tunable centre frequency and bandwidth without the need for adjusting the inter‐resonator couplings. This is achieved by cascading a quasi low‐pass filter and a quasi high‐pass filter, while minimizing interaction between the filters without the need for an isolator between the filters. Simulated results are presented. Copyright © 2013 John Wiley & Sons, Ltd.     

三调谐电力滤波器的研究

在分析单调谐滤波器和双调谐滤波器特性的基础上，提出了一种等效于三组单调谐滤波器的三调谐滤波器，该滤波器由3个电感和3个电容组成；分析了该滤波器的阻抗特性，给出了参数的计算方法, 通过额定电压、调谐频率、并联谐振频率和补偿容量等已知数据计算出电感和电容元件的参数；并针对一110kV实际电网，完成三调谐滤波器设计计算、仿真分析和试验测试。结果表明该滤波器有良好的滤波性能，可以同时滤除三种不同频率的谐波，频率误差不超过2Hz，性能优于三组单调谐滤波器，具有基波损耗低、占地小、投资省、只有一个电抗器接受冲击电压、只需要一个开关等优点，适合在电力系统推广应用。     

Electronically Tunable Filters

In this article, a brief introduction to the development of tunable filters was given. A classical design technique based on a combline filter approach was shown, where minimum degradation in passband performance could be obtained across a broad-tuning range. The fundamental disadvantages associated with the conventional resonator tuning approaches were also discussed, recognizing the importance of developing new techniques for realizing tunable microwave filters. It was shown that there is a possibility in realizing an electronically reconfigurable microwave filter based on parallel- coupled switched-delay lines, which possesses the important property of maintaining constant absolute bandwidth over almost an octave of tuning bandwidth. Furthermore, the filter has the ability to incorporate active switching elements in the filter circuit, without sacrificing its loss and linearity performance. With the exceptional linearity performance and power handling capability, the filter is readily adapted to poor environments. Although the use of p-i-n diodes as switching elements would result in large dc consumption, the approach could also be readily adapted for use with any switches, such as pHEMT or RF MEMS switches, to achieve extremely low power consumption. The integration of switchable couplings to enable both bandwidth and center frequency to be reconfigurable would be an enhancement.     

一种新型可调谐微带带通滤波器的设计

利用微带线的原理和电压调谐变容二极管的特性,结合对射频捷变信号源中常用的上变频系统的研究,设计出一种中心频率可调谐、相对带宽可调谐、可进行精度校准的微带带通滤波器。该滤波器针对射频输出中包含的多种杂散分量的特征,应用单级滤波网络或谐振网络进行专门抑制再级联,具有原理简单、结构灵活、易于扩展、调谐速度快、工作频带宽、尺寸小、成本较低等优点。实际测试结果与利用Serenade8.7软件仿真结果基本一致,性能指标能够达到设计要求。     

基于CompactRIO的光纤布拉格光栅解调系统

波长解调技术是光纤布拉格光栅传感器实用化面临的关键技术,提出并实现了一种基于可调谐Fabry-Perot滤波器的FBG解调系统。该系统通过NICompactRIO平台控制D/A输出信号作为可调谐滤波器的扫描信号,同时对布拉格光栅的反射波峰进行采样与处理,通过标准具和参考光栅对Fabry-Perot滤波器进行标定。实验表明,该解调系统扫描带宽50nm,在50Hz扫描频率内,可以得到稳定测量信号。     

VCO/RADIATOR MODULE TUNED BY FERROELECTRIC VARACTOR

ABSTRACT

Design of tunable Gunn diode—based active antenna module including a new type of planar dielectric resonator (PDR) tuned by a ferroelectric (FE) varactor is presented. The module is designed in such a way that the PDR acts both as a stabilizing resonator and as a radiator. MW properties of FE elements used for VCO tuning are considered. The module operates at frequency around of 17 GHz and demonstrates the radiated power of 8.8 ± 0.1 dBm over the 130 MHz tuning range and a phase-noise level of ?95 dBc/Hz at 100 kHz offset. 65° width of the radiation pattern in both the E and H planes corresponding to a gain of 5.1 dBi was measured. The maximal VCO power limited by the dielectric nonlinearity of a FE film in the microwave electric field and by the FE film overheating is estimated for FE film-based varactors of the planar and parallel structures.     

An ultra-low-power,low-noise tunable electrocardiogram amplifier

The objective of this research work is to propose an innovative low-power, low-noise, tunable three-stage capacitive instrumentation amplifier, capable of receiving and magnifying the electrocardiogram (ECG) signals. This is done by adding an extra stage to the second stage of the conventional capacitive instrumentation amplifier. The results show similar midband gain with lesser capacitor usage and smaller chip occupancy area with provision of concurrent tunable gain and bandwidth. The proposed amplifier is designed and implemented using TSMC 0.18-μm CMOS technology scale under a 1-V supply voltage with the simulation process carried out using Cadence Virtuoso tool. Post-layout simulation results show that the amplifier has a tunable midband gain of 55 to 65.6 dB, low-cutoff frequency tuned from 377 mHz to 4.5 Hz and high-cutoff frequency tuned from 86.8 to 263.6 Hz. The simulated value of the input-referred noise and noise efficiency factor (NEF) of the amplifier are 9.6 μV_rms and 6.1, respectively, with the total power consumption of 71.2 nW.     

基于方形开环的双模滤波器设计

在传统方形开环谐振器的基础上,设计了一种新型的双模微带滤波器,该滤波器包含两个方形开环谐振器,在每个传统谐振器内部添加微带支路结构,通过微扰来实现频响特性的改善,由仿真结果可以看出,该设计的带内特性良好,带内波纹小于0.3dB,通带边沿均插入了传输零点,且传输零点处的S21〈40dB,截止边沿陡峭,实现了6%的相对带宽,整个滤波器的尺寸大小约为30mm×20mm,改进后的结构与传统结构相比降低了0.5GHz的中心频率,相对减小了16%的面积,进一步实现了小型化。     

采用阶梯 T 型谐振器的双陷波 UWB 滤波器

为有效抑制印度国家卫星通信C频段和X卫星频段对超宽带通信系统的干扰,提出了一种新型双陷波超宽带滤波器。该滤波器采用阶梯T型多模谐振器(multimode resonator, MMR)与缺陷地结构(defected ground structure, DGS)的交趾耦合,实现超宽带特性。采用非对称耦合线及在MMR两侧耦合分裂环谐振器的方法,分别在6.67～7.06 GHz, 7.47～7.57 GHz两个频段内产生陷波。实测结果与仿真结果吻合较好,该滤波器的通带范围为3.03～11.50 GHz, 3 dB带宽达到123%,插入损耗仅有0.87 dB,两处陷波中心频率分别在6.87 GHz和7.52 GHz,陷波深度均大于20 dB,且整体尺寸紧凑,仅有16 mm×8 mm大小。     

A roll eccentricity sensor for steel-strip rolling mills

The problem of roll eccentricity compensation in steel-strip rolling mills is examined. A novel roll eccentricity sensor is proposed for the task of retrieving the desired reference signal from the available roll-force measurement. The sensor implements a modified comb filter structure which can be arranged in either tunable or adaptive form. Simulation results based on typical experimental data indicate that the proposed sensor is appropriate and offers distinct advantages over other methods. The proposed comb filter is new in the sense that it consists of a number of second-order notch filter models with specially constrained bandwidth characteristics. An approximate gradient-based adaptive algorithm is used for the frequency estimation. The important feature of such an algorithm is that it is robust and is simple to implement. The advantages of the sensor include fast convergence and accurate parameter estimates. No extra positional sensors are required since this information can be easily obtained from the phase estimates. Finally, the sensor is not based on approximate mill models; it treats the problem as a harmonic series buried in noise. The resulting solution is based on time domain measurements that characterize the mill roll eccentricity conditions during operation     

同步调谐可变带通滤波器的设计

中心频率固定而带宽变化的可变带通滤波器广泛应用在许多电子测量仪器中,本文首先介绍了可变带通滤波器的实现背景,并着重介绍了可利用同步调谐滤波器来实现这种滤波器的理论依据和实际电路.通过电路分析和数学推导可以证明,电路中采用幅度补偿是可行的,并具有优势.     

基于时间尺度变换策略的幅频测量用自适应陷波器算法

现有电力信号幅频测量算法在动态条件下的测量精度和响应时间方面还有待改善,为此提出了基于时间尺度变换的自适应陷波器(adaptive notch filter,ANF)算法进行幅频测量。该算法对时间进行尺度变换,得到新时间尺度下的ANF动态方程,能够消除频率参数和滤波器之间的非线性耦合,将状态估计方程等价为线性时不变系统,并进行离散化处理。该算法能够有效消除谐波和噪声干扰,快速准确地测量动态变化的幅值和频率。算例结果验证了该方法的有效性,可满足在线测量的要求。     

A reconfigurable high ultimate rejection inductorless band‐pass filter by the use of N‐path passive mixers

In this paper, a band‐pass filter with a tunable bandwidth and the center frequency is introduced, which employs N‐path and N × M‐path passive mixer structures, for multiband multistandard wireless receivers. The center frequency of the proposed filter is tunable from 0.1 to 1 GHz, while its bandwidth is also adjustable from 6% to 34% of the center frequency at 100 MHz. The passband ripple is reduced by applying a Miller compensation technique, resulting in a worst‐case ripple of only 1.6 dB over the entire tuning range. An additional eight‐path filter is also utilized at the input of the circuit, which highly improves the out‐of‐band rejection of the filter as well as its out‐of‐band linearity. The noise figure and the input return loss are, respectively, better than 5 and 10 dB, and depending on the desired center frequency, the total power consumption of the proposed filter varies from 41 to 70 mW.     

单调谐滤波器的自动调谐控制

为解决滤波器失谐问题,建立了自动连续调谐滤波器的实验系统,在单调谐滤波器中引入自动调谐功能 自动调谐系统由连续可调电抗器和自动调谐控制系统组成。电抗器用双绕组正交磁化原理,改变控制绕组的直流 电流可在线连续调节电感量,电抗器有反向调节特性和足够的调节范围,能满足滤波器失谐的补偿要求。控制系 统以滤波器的h次谐波阻抗角为控制目标,采用PI调节规律和设定限幅与死区等策略,保证了自动调谐系统的性 能和稳定性。实验结果证明了失谐补偿策略的正确性和自动调谐滤波器的可行性。     

倒置微带贴片谐振器测量汽轮机湿度的研究

汽轮机蒸汽湿度的在线测量,对汽轮机的安全、经济运行具有重要的理论意义和实用价值。根据微扰法的基本理论,提出一种结构简单、灵敏度高的倒置微带贴片谐振器,实现汽轮机湿度的准确在线测量。湿蒸汽的湿度变化反应为谐振器介质层介电常数的变化,根据微带贴片谐振器的基本原理,仿真计算不同介电常数下的谐振频率,得到其变化关系曲线;讨论样本厚度、基质厚度和基质介电常数对频率偏移量的影响;设计微带贴片谐振器模型,并分别在HFSS和CST软件下进行仿真。研究及仿真结果表明,微带贴片谐振器模型适用于汽轮机蒸汽湿度的在线测量,蒸汽湿度每变化1%,谐振器频偏约为18 k Hz,约为微带缝隙谐振器频偏的3.6倍,有利于蒸汽湿度的准确测量。     

扩展压电传感器频率响应范围的方法研究

为了进一步提高压电传感器及其信号调理电路的低频响应能力,扩展压电传感器的工作频带,通过分析压电传感器电荷放大电路的频率响应情况,提出了采用数字滤波器进行补偿的方法。利用对压电传感器标定后获得的输入输出和MATLAB软件设计了FIR滤波器,并将传感器测试系统与滤波器串联来复现原有被测信号。仿真结果表明该方法使压电测量系统的工作带宽得以扩展,进一步降低了整个压电测量系统的低频截止频率,达到了减小动态测量误差的目的。