电调谐滤波器的研究与设计

介绍了可调谐滤波器的电路结构,解释了设计中采用电感耦合并联谐振电路的具体原因。给出了变容二极管的等效电路,并对由变容二极管构成的滤波器的最大频率可调范围进行了分析。设计制作了一个VHF频段的电调谐滤波器,并使用安捷伦公司的微波电路仿真软件ADS进行仿真,测试表明,此滤波器的频率可调范围为100～260 MHz,插入损耗小于3.8 dB,驻波系数小于1.65。同时在频率的可调范围内对滤波器的插入损耗和矩形系数的变化进行了分析,实验结果和理论分析吻合较好。     

作弊防控系统中独立可调双频带通滤波器设计

文章提出了一种独立可调双频带通滤波器.该滤波器主要由一对加载变容二极管的并联耦合短路线、一对加载变容二极管的λ/2开路谐振器和公共输入输出部分组成.变容二极管和并联耦合短路线并联构成一个谐振器,产生第一通带.λ/2开路谐振器加载变容二极管,产生第二通带.通过改变加载在变容二极管上的偏置电压来改变变容二极管的电容值,使谐振器的谐振频率发生偏移,从而调节滤波器工作频率.结果表明,第一通带和第二通带的中心频率变化范围分别为0.2~0.4GHz和1.2~1.42GHz,调节百分比分别为66.5%和15.4%.仿真与测试的结果吻合良好,证明该设计方法是有效的.该滤波器可应用到作弊防控系统中.     

基于枝节加载型SIR的可调滤波器

基于枝节加载型阶梯阻抗谐振器(SIR)设计了一种加载变容二极管的微带可调带通滤波器。SIR结构利于抑制高次谐波且可实现滤波器的小型化,提出的模型通过在SIR的中心平面加载2个枝节构成多模谐振器。通过奇偶模方法分析了枝节加载型SIR的谐振特性;通过加载变容二极管实现了对滤波器奇偶模谐振频率的独立控制,利用变容二极管容值的变化实现了滤波器的中心频率可调,中心频率随变容二极管偏置电压的增加而增大。该可调滤波器实现了在0.82~1.17 GHz范围内中心频率可调且插入损耗小于5 dB,回波损耗大于10 dB。     

一种小型化电调正交耦合器

该文提出了一种3dB正交电调耦合器。该耦合器基于传输线变换技术进行设计,利用变容二极管调节3dB正交耦合器的中心频率,实现了从1.8~2.8GHz的中心频率调节范围,在可调范围内实现S11优于-15dB,S31大于-4.4dB,直通和耦合端的相位差为90±5°。该耦合器具有结构紧凑,偏置电路简单的优点。     

基于电长度可调的可重构功分器设计

根据分支线耦合器的功率合成效率会受输入功率相位差的影响,通过含变容二极管的π型电路将其级联在3dB Wilkinson功分器的后端,实现原功分器的功率再分配。通过调节变容二极管的偏置电压改变π型电路的等效电长度实现相位差,可实现功分器的分配比例可调。在此原理上,基于ADS软件设计了两款工作频率为2.5GHz的可重构功分器,可分别实现分配比例在0~25dB(约1∶1~300∶1)和-15.5~15.5dB(约1∶35~35∶1)范围内连续可调,且其回波损耗和输出端口间隔离度均优于20dB,适用于射频与微波系统中的实时功率分配与合成。     

基于功率反射法的E 型可重构功分器

基于对功率反射电路和级联传输线的分析计算,提出了一种新型分配比可重构方法。奇-偶模分析表 明,当改变功率反射电路中级联传输线的电长度时,可以实现任意范围的功率分配比连续可调。在此原理的基础上,利 用E 型调谐电路代替级联传输线,设计了一款工作在2. 45 GHz 的E 型可重构功分器。仿真和实物测试得到,当E 型 调谐电路中变容二极管的偏置电压在0~20 V 范围内改变时,可重构功分器的功率分配比可以在-21. 3~22 dB 之间连 续可调,同时回波损耗和隔离度均优于20 dB,插入损耗低于1. 3 dB。     

K波段推-推介质振荡器设计

为了满足现代通信系统对于高频率与高稳定性信号源的需求,提出一种K波段介质振荡器。该振荡器通过推-推结构将两路子振荡器合二为一,使其能够在一个电路中同时实现振荡器和倍频器。在介质谐振器的两条耦合微带线上增加变容二极管模块,通过改变变容二极管的偏置电压调整谐振器中传输信号的相位。变容二极管模块的加入能够有效降低有源器件不一致性对电路的影响,减少两个子振荡器在基频处对输出信号的干扰,同时让振荡器获得200 MHz左右的输出信号频率可调范围。测试结果表明:在输出频率为20.96 GHz时,输出功率约为-4.59 dBm,在10 kHz时达到-66.50 dBc/Hz的相位噪声,在100 kHz时达到-94.31 dBc/Hz的相位噪声,基波抑制度达到-25.42 dBc。     

一种新型定向耦合器的耦合性质

文章介绍了一种新型的耦合器—左右手组合介质定向耦合器。该耦合器的主传输线采用传统的微带线结构,而耦合电路则采用近年来引起广泛注意的左右手组合材料。左右手组合材料采用在微带线上加载集总元件变容二极管实现了耦合频率的连续移动。实验发现,当加载变容二极管的电压升高时,耦合强度随之变化且耦合频率向高频方向移动。     

光控振荡器

变化照射到光敏电阻上的光量可改变振荡器的频率。照射光敏电阻R_L确定光耦合器的光输出量,由此决定了光二极管的输出量。振荡调谐电路组成部分的变容二极管上的偏压取决于光敏电阻上的照度,因而其光的强弱就设置了振荡器的频率。     

一种小型化电调功分器设计

该文提出了一种等功分电调功分器。该功分器基于传输线变换技术进行设计,利用变容二极管调节功分器的中心频率,实现了从900～1050MHz的中心频率调节范围,在可调范围内实现S11小于-20dB。S21、S31大于-3．2dB,S23小于-22dB。该功分器具有尺寸小,偏置电路简单的优点。     

A Reconfigurable High-Gain Partially Reflecting Surface Antenna

A high-gain partially reflective surface (PRS) antenna with a reconfigurable operating frequency is presented. The operating frequency is electronically tuned by incorporating an array of phase agile reflection cells on a thin substrate above the ground plane of the resonator antenna, where the reflection phase of each cell is controlled by the bias voltage applied to a pair of varactor diodes. The new configuration enables continuous tuning of the antenna from 5.2 GHz to 5.95 GHz using commercially available varactor diodes, thus covering frequencies typically used for WLAN applications. Both the PRS and phase agile cell are analyzed, and theoretical and measured results for gain, tuning range, and radiation patterns of the reconfigurable antenna are described. The effect of the varactor diode series resistance on the performance of the antenna is also reported.      

Varactor-tuned integrated Gunn oscillators

Electronic tuning of Gunn diodes in hybrid integrated circuits has been studied. Microstrip transmission lines were used to form resonant circuits into which a Gunn diode and a varactor diode were mounted to provide the microwave power and frequency tuning, respectively. Basically, two types of circuits have been investigated. The first is a half-wavelength open-circuited microstrip `cavity' with this transmission line and the varactor diode attached between the end of the cavity and an RF ground. The second is a lumped LC circuit in which the inductance of a short high-impedance microstrip line is resonated with the lumped capacitance of the varactor diode. The latter circuit provides a tuning range of over 10 percent at 7.5 GHz. The power output varies within 2 dB in the tuning range.     

Compact Frequency and Bandwidth Reconfigurable Microwave Filter

This paper details the construction and working of a compound reconfigurable filter capable of frequency and bandwidth reconfiguration in the frequency range from 2 to 3 GHz. The switching between frequency and bandwidth reconfiguration is inherited by two PIN diodes. Bandwidth tuning is facilitated by tuning two transmission zeros individually using varactor diodes, giving flexibility in reconfiguring the upper and lower pass edges. The two transmission zeros are obtained using simple concentric square loop resonators. The maximum bandwidth obtained is 1.5 times the minimum bandwidth offered by the filter. Hence the filter can be used for dynamic bandwidth allocation. This prototype is fabricated and validated in real-time. The simulated and measured results are analogous to each other.

     

Fixed-Beam Frequency-Tunable Phase-Reversal Coplanar Stripline Antenna Array

A fixed-beam frequency-tunable coplanar stripline (CPS) antenna array using the phase reversal technique and varactor diodes tuning is presented. The antenna array is composed of plurality of half-wavelength CPS sections interconnected by phase reversing crossovers. These crossovers have two functions: they serve as the radiators (small dipoles) of the array and also provide their own required in-phase excitations for broadside radiation. Two microstrip-to-CPS transitions for excitation of the balanced input/output antenna array are implemented and compared. A six-element array is demonstrated theoretically and experimentally, with 9.3 dBi of gain for bidirectional radiation and 12.5 dBi of gain for unidirectional radiation using a back reflector. Moreover, shunt varactor diodes are incorporated along the CPS structure to achieve frequency tuning through a bias voltage control while broadside radiation patterns remain fixed. The return loss and the radiation patterns at several frequencies are presented, and up to 50% tuning range is obtained. The proposed antenna array is simple and uniplanar with small lateral size, high radiation efficiency and high directivity. In addition, it uses a very simple biasing circuit with high DC-RF isolation. Its balanced input/output makes it suitable for RF system integration and active integrated antenna design.     

Continuous phase shift of sinusoidal signals using injection locked oscillators

This work presents an alternative to generate continuous phase shift of sinusoidal signals based on the use of super harmonic injection locked oscillators (ILO). The proposed circuit is a second harmonic ILO with varactor diodes as tuning elements. In the locking state, by changing the varactor bias, a phase shift instead of a frequency shift is observed at the oscillator output. By combining two of these circuits, relative phases up to /spl plusmn/90/spl deg/ could be achieved. Two prototypes of the circuit have been implemented and tested, a hybrid version working in the range of 200-300 MHz and a multichip module (MCM) version covering the 900-1000 MHz band.     

Macro-micro frequency tuning antenna for reconfigurable wireless communication systems

A small-sized (radiator sime10times8 mm) microstrip monopole antenna for reconfigurable macro-micro frequency tuning is presented. The proposed antenna operates in WiBro (2.3-2.4 GHz) and WLAN 802.11a/b (2.4-2.48 GHz/5.15-5.35 GHz) service bands with a constant antenna gain. Two frequency tuning diodes, a pin diode and a varactor, are incorporated into a meander type radiator. The pin diode is used for frequency switching (macro-tuning) between 2 GHz band and 5 GHz band. In addition, the varactor is used for frequency tuning (micro-tuning) within wireless service bands (2.3-2.48 GHz and 5.15-5.35 GHz) to produce constant antenna gain     

Varactor Tuning Diodes as a Source of Intermodulation in RF Amplifiers

In RF amplifiers used in the front ends of VHF receivers which are to be tuned over a wide frequency range, varactor diodes are often used to accomplish the necessary change in tuning capacitance. nce. The variation of capacitance with dc voltage which enables the tuning function to be accomplished results in a nonlinear characteristic stic which, in turn, introduces harmonic and intermodulation dtion.storon. This paper is concerned with the determination of tef12f 1-J2) intermodulation distortion product generated by the varactor diodes and modified by the characteristics of the input tuned circuit. Both third-order and "distortion-on-distortion" second-order intermodulation mechanisms are included in the calculation. An expression is presented for the magnitude of the (2f1-f2) intermodulation intercept which includes the effects of the characteristics of the tuned circuit and the various parameters used to characterize the varactor diode. Design considerations combining both the linear and the intermodulation ation performance of the input circuit are discussed, including design tradeoffs and interrelationships among the circuit parameters and performance variables. Illustrative calculations are given based on the characteristics of the MV3102 varactor diode.     

一种简易微波VCO的设计*

描述了一种高性能简易微波VCO器件的设计和实验。该器件基于负阻原理设计,利用微波FET和变容二极管等分立元件制作,具有高性价比的特点。设计过程中利用ADS软件进行电路的匹配和优化,通过合适的外电路设计对变容二极管VCO的调频线性度进行改善,同时,降低了VCO的相位噪声。实际电路的测试结果表明,当该VCO的中心频率为4.3GHz时,其调谐范围大于200MHz,输出功率大于5.2dBm,相位噪声优于-112dBc/Hz@1MHz和-83dBc/Hz@100kHz。     

A 110–140 GHz Millimeter-Wave VCO Using Varactor and Bulk Effective Technique in 65 nm CMOS Process

In this paper, an enhanced voltage controlled oscillator (VCO) at center frequency 125 GHz with tuning rang of 24% is presented. The proposed idea is based on the tuning capacitance using MOS varactor. The structure is consisted of applying an MOS varactor capacitor to the drain and bulk (in parallel) of NMOS transistor in 65 nm CMOS standard technology. The obtained output of the proposed VCO at 2nd harmonic is tunable at 110–140 GHz frequency with applying?±?1.2 input tuning voltage. Simulation results of the proposed circuit are obtained after extracting post layout (with total chip size of 0.07 mm²) and confirm theoretical results. Compared to the resent designs, the obtained results indicate that the proposed circuit has high tuning range, low die area and a good figure of merit @ 1.2 power supply voltage.