FDM-channel selection filter employing an arrayed-waveguide gratingmultiplexer

A novel channel selection filter based on an arrayed-waveguide grating multiplexer is reported for optical frequency-division-multiplexer (FDM) networks. The filter employs fold-back optical paths and optical switches, and can be operated digitally with multiple switches. A 16 channel selection filter employing a silica-based 16×16 multiplexer achieves a 20 GHz bandwidth and a crosstalk of less than 27 dB     

FDM-channel selection filter using arrayed-waveguide gratingmultiplexer with input and output switches

A novel configuration is reported for a tunable channel-selection filter that employs an arrayed-waveguide grating (AWG) multiplexer and optical switches. The filter requires only 2(√N-1) 1×2 switch elements to select one of N frequency-division-multiplexed (FDM) channels. A filter for 100 GHz-spaced 16 FDM channels is demonstrated with an AWG 16×16 multiplexer and six 1×2 switches     

基于逻辑切换的改进强跟踪卡尔曼滤波器

针对线性随机系统提出了一种改进强跟踪卡尔曼滤波器(MSTKF).通过改变强跟踪滤波器的多重时变渐消因子,MSTKF在卡尔曼滤波和强跟踪滤波两种工作状态之间切换.当卡尔曼滤波不能有效跟踪突变状态时,MSTKF切换为可变弱化因子的强跟踪滤波.数值仿真实例显示了本方法的有效性.     

High-Qfactor shunt-switched N-path filters

At its fundamental resonant frequency, a shunt-switched N-path filter is similar to an LCR resonant circuit, except that the selectivity or Q factor achievable, which is a direct function of the passive components employed, may be very much better than normally available in tuned circuits. The limit on the maximum attainable Q factor is shown to depend on the impedance of the shunt arm switches and filter load, as well as the speed of the switches.     

Filters for High-Speed Diode Modulators and Demodulators

The relationship between switching time, transient suppression, and filter complexity is derived for filter-type diode switches, along with the theoretical minimum switching time. Design criteria are developed for high-speed switches and detectors in waveguide and TEM transmission lines.     

Programmable Bandpass Filter and Tone Generator Using Bucket-Brigade Delay Lines

Bucket-brigade devices have been used to build a new type of active filter that is equivalent to a second-order digital filter without the need for complex analog-to-digital conversion. The filter response characteristics, i.e., center frequency and bandwidth, depend on the circuit parameters of gain and clock frequency, both of which may be electronically controlled. By using a variable clock signal, 1023 frequencies can be accurately selected by the proper setting of ten switches. The selected clock frequency uniquely determines the center frequency of the bucket-brigade filter. The programmable feature of the clock circuit, therefore, allows the convenient selection of the center frequency of the bandpass filter. A slight modification to the programmable bandpass filter converts it into a programmable oscillator. Thus, any one of 1023 tones can be generated by the proper setting of the switches. A device that exhibits both filter and oscillator functions has been demonstrated in the laboratory.     

Zero-voltage and zero-current-switching PWM hybrid full-bridge three-level converter

This paper proposes a zero-voltage and zero-current-switching pulsewidth modulation hybrid full-bridge three-level (ZVZCS PWM H-FB TL) converter, which has a TL leg and a two-level leg. The voltage stress of the switches of the TL leg is half of the input voltage, and the switches can realize ZVS, so MOSFETs can be adopted; the voltage stress of the switches of the two-level leg is the input voltage, and the switches can realize ZCS, so IGBT can be adopted. The secondary rectified voltage is a TL waveform having lower high-frequency content compared with that of the traditional FB converters, which leads to the reduction of the output filter inductance. The input current of the converter has quite little ripple, so the input filter can also be significantly reduced. The operation principle of the proposed converter is analyzed and verified by the experimental results. Several ZVZCS PWM H-FB TL converters are also proposed in this paper.     

A 25–75-MHz RF MEMS Tunable Filter

This paper presents a state-of-the-art discrete RF microelectromechanical systems (MEMS) tunable filter designed for 25-75-MHz operation. This paper also presents an enhanced model of the RF MEMS switch, which is used for accurate prediction of the tunable filter response. The two-pole lumped-element filter is based on digital capacitor banks with on-chip metal-contact RF MEMS switches and lumped inductors, and results in a tuning range of 3:1 with fine frequency resolution, and a return loss better than 13 dB for the entire tuning range. The relative bandwidth of the filter is 4 plusmn 1% over the tuning range and the insertion loss is 3-5 dB, limited mostly by the inductor Q and the switch loss. The IIP₃ measurements prove that tunable filters with metal-contact series RF MEMS switches show extremely linear behavior (IIP₃ > 68 dBm).     

A compact low-loss reconfigurable monolithic low-pass filter using multiple-contact MEMS switches

A high-performance reconfigurable low-pass filter based on the quasifractal self-similar structures has been developed at millimeter-waves using multiple-contact MEMS switches. Three-cell cascaded low-pass structure was reconfigured to one-cell low-pass counterpart by activating the micromachined switches to achieve 3:1 frequency scaling. Two types of special multiple-contact MEMS switches were developed to reduce the number of switching elements as well as to reduce the insertion loss and, thus, extend the operating frequencies to mm-waves. In addition, bias-decoupling circuits were eliminated, resulting in a small chip size of 1.2 mm /spl times/ 1.5 mm. The measured 3-dB cut-off frequency of the reconfigurable low-pass filter changed from 67 GHz to 28 GHz with minor change in the insertion loss from 0.32 dB to 0.27 dB. This work demonstrates the possibility of high-performance compact-size reconfigurable filters at mm-waves using multiple-contact micromachined switches.     

Switched-capacitor filters driven with very low voltage clock signals

It is well known that the switches of a very low voltage (1.5V) switched-capacitor filter in a standard CMOS process must be driven with a clock signal higher than the power supply, often generated on-chip. The authors present, however, a technique to implement very low voltage switched-capacitor filters with switches driven at the same very low voltages.<>     

Integrated 18th-order pseudo-N-path filter in VIS-SC technique

An integrated 18th-order frequency symmetrical switched-capacitor (SC) bandpass filter is described that was realized by the use of voltage inverter switches (VISs) in the form of recharging devices. The filter was implemented in a standard CMOS technology. It was conceived for use as a `channel filter' in modulation schemes for PCM/FDM and audio/FDM conversion. Starting from a high-pass filter as reference filter, the SC filter is designed as a pseudo-N-path filter, with N=2. The application of the pseudo-N-path principle leads to a substantial saving in hardware.     

超声探伤中的多通道滤波器的设计与应用

介绍了一种超声探伤中脉冲信号的数据采集与初步处理的方法。该方法基本可由通用部件实现，包括由PIC单片机控制的多通道带通滤波器组、前端放大电路、一台工业控制计算机。由工业控制计算机向PIC单片机发出控制指令，单片机进行指令验证和识别，通过矩阵电路切换所需中心频率的滤波器接入系统，进行数据处理。关键技术为多通道带通滤波器组的设计、矩阵电路的设计、采样数据的处理。本方法已在某型钢管超声探伤实验设备中使用，效果良好。     

On ‘A new wide range free-running multivibrator’ and ‘A stable square-wave generator’

An approach to voltage controlled filtering is presented in this work. The method in based on a linear system with periodically operated synchronous switches. Digital simulation results are presented and compared with those obtained via a hardware implementation of the filter. The simplicity of the approach makes the filter attractive for a variety of applications.     

High frequency GaAs switched capacitor filter implemented with GaAs insulated gate FET switches

A switched capacitor filter implemented with 5 mu m GaAs IGFET switches and GaAs MESFET operational amplifiers is presented. The circuit is clocked at 25 MHz. By scaling to 1 mu m IGFETs, a switching speed of about 625 MHz should be attainable. Use of GaAs IGFET switches is shown to greatly reduce power consumption and complexity of the circuit. The low frequency switching instability of the GaAs IGFET is shown to be of no consequence in this application.<>     

Programmable acoustic-surface-wave oscillator

A programmable acoustic-surface-wave oscillator composed of a filter bank, an amplifier and diode switches is described. The input transducer and the ten output transducers of the filter bank are deposited on a quartz substrate; the direction of the launched acoustic beam being a function of frequency. The device may oscillate at ten different frequencies in a range of 9 MHz (121?130 MHz)     

基于滤波器综合分析法的118 GHz单刀二掷开关

采用滤波器综合分析方法, 基于分立式AlGaAs/GaAs异质结PIN二极管, 根据其等效寄生参数, 综合出单刀二掷开关集总参数滤波器模型, 以此分析其等效分布参数电路, 设计出了118 GHz星载辐射计用单刀二掷开关准单片, 开关电路尺寸6×2.5×0.1 mm3.通过开关模块封装用波导-微带过渡和键合金带插损的分析研究, 研制出了低插损的118 GHz开关模块, 在110~120 GHz, 测得开关插损小于3.0 dB, 插损典型值2.6 dB;开关隔离度大于22 dB;开关响应时间、导通时间、关断时间、恢复时间分别小于18 ns、20 ns、10 ns、18 ns, 该准单片作为通道切换开关可集成应用于118 GHz收发组件中.     

Novel high-isolation FET switches

This paper describes novel high-isolation monolithic microwave/millimeter-wave integrated circuit (MMIC) field-effect transistor (FET) switches that have higher isolation characteristics than conventional switches without much insertion loss degradation. The newly developed switches consist of series/shunt FETs and T-shaped R-C-R circuit. Each FET switch utilizes the parasitic capacitive component of the FETs in the off-state to produce a band-rejection filter at the operating frequency. The design method of the newly proposed switches and their characteristics are described herein. With this method, the isolation characteristics are improved by more than 15 dB between 5.4 GHz and 6.4 GHz and more than 20 dB between 5.5 GHz and 6.1 GHz over conventional values     

基于RF MEMS开关的交指型可切换带通滤波器设计

为了有效解决信号/频谱分析仪等微波测试仪器尺寸较大、信号损耗高、选通切换效率差等问题,将射频MEMS开关引入交指型可切换滤波器结构中。通过MEMS四掷开关选择具有不同中心频率的交指型谐振器,实现在6~14 GHz内四个频率的射频信号切换过滤。利用HFSS电磁波仿真软件对滤波结构的几何参数进行优化计算,得到四个可切换频率的插入损耗,分别为1.26 dB@6.86 GHz、1.03 dB@9.16 GHz、1.23dB@11.78 GHz、1.07 dB@12.26 GHz,整体面积约为7.95 mm³。与其他可切换滤波器相比,该可切换滤波器将MEMS四掷开关与交指型谐振器集成到一起,具有低插损、小尺寸、高集成度等优点。     

数控可选通微带滤波器组的设计与仿真

设计了宽频带数控可选通微带滤波器组,采用微波开关实现滤波器组的单个选通。分析了电容加载谐振器的谐波特性,每个带通滤波器被设计成梳状线结构,并用先进的设计系统(ADS)优化其结构参数。数控滤波器组由两片带译码器的微波开关芯片和4个微带滤波器构成。仿真结果表明,三位二进制编码控制每个滤波器的通断,可实现500～2 000 MHz频段滤波器的选通。     

Matrix converter controlled with the direct transfer function approach: analysis,modelling and simulation

Power electronics is an emerging technology. New power circuits are invented and have to be introduced into the power electronics curriculum. One of the interesting new circuits is the matrix converter (MC), and this paper analyses its working principles. A simple model is proposed to represent the power circuit, including the input filter. The power semiconductors are modelled as ideal bidirectional switches and the MC is controlled using a direct transfer function approach. The modulation strategy of the converter is explained in a complete and clear form. The commutation problem of two switches and the generation of overvoltages are clarified. The paper also includes a soft-switching commutation method that allows for a safe commutation of the switches. Finally a complete simulation scheme, using Matlab®–Simulink®, is discussed.