Supplementary all-pass sections with reduced number of passive elements using a single current conveyor

Four new configurations realizing current conveyor-based first-order all-pass filters are proposed. Using these configurations two types of first-order voltage-mode allpass filter can be realized. The circuits employ a single positive type secondgeneration current conveyor (CCII+) and only three passive components. For each topology only a simple component matching constraint is required. To illustrate the design possibilities provided by the introduced circuits an oscillator circuit consisting of the proposed all-pass filters is constructed and experimentally tested.     

Low input resistance current buffer stage using a controllable positive feedback loop,and applications of current conveyor based filters

A novel current buffer stage with very low input resistance is proposed. Low input resistance is achieved using a potentially instable positive feedback loop. Stability of the circuit under different operating conditions is examined in details. A feedback control block using a bipolar 4-bit current steering DAC as a control mechanism is added to the buffer to control the input resistance and assure stability. The proposed technology-independent design methodology always ensures precision and stability for all different parasitic capacitor and resistor values of the driving signal source as well as for process, mismatch, and environmental variations. Additionally, a novel second generation current conveyor circuit based on this novel input buffer is presented to demonstrate how this buffer makes almost ideal current mode circuits possible. Filter applications using the proposed CCII are performed for further justification. The current buffer and CCII were built in AMS 0.35 μm 2P4M CMOS technology. Measurement results are presented for the current buffer, the CCII circuit, and the filters.     

A multi-port D-R mutator using CCIIs with current followers

A multi-port D-R mutator with new current conveyors (CFCCIIs) as the four-port active element is proposed. Each CFCCII consists of a current follower added to a second-generation current conveyor (CCII). This proposed circuit is a simple configuration using CCIIs, CFCCIIs and grounded capacitances and is applied to higher order high-pass filters. This configuration can realize a superior transmission characteristic, inheriting the characteristic of the conventional LC filter. Since all the passive elements are grounded, the influence of parasitic elements of current conveyors can be reduced with this circuit configuration. As a result, this circuit is considered a suitable configuration for monolithic integration. Results obtained from the SPICE simulations show the realized filters have excellent performance and the circuit is effective.     

基于电流传送器的椭圆函数滤波器设计

本文采用电流传送器CCII+/-的模块单元设计实现高阶椭圆函数滤波器,实现方法为对所设计的无源高阶滤波器用信号图（SFG）进行模块化综合,用电流传送器CCII+/-实现SFG中的各个模块单元。所实现的有源CCII+/-滤波器中所有电阻,电容都接地,适于全集成。     

Tunable frequency versatile filters implementation using minimum number of passive elements

Two new universal active current-mode filters are proposed, one topology of which is with three inputs and one output, the other prototype is with single input and three outputs counterpart. One proposed circuit employs two current conveyors, two grounded capacitors and two resistors, wherever the other proposed circuit employs two current conveyors, two grounded capacitors and two multi-input, multi-output Operational Transconductance Amplifiers(OTA) as variable resistor for tuning the cutoff frequency of realized filters. Without changing the passive elements, the proposed circuits employ features of multifunctional, convenient for integration, low sensitivities and simple in structure.     

CCII based more tunable voltage-mode all-pass filters and their quadrature oscillator applications

In this paper, two new voltage-mode (VM) first-order all-pass filters using single active element namely second-generation current conveyor (CCII) and a grounding capacitor are proposed. The first proposed filter employs a dual output CCII (DO-CCII) and the other one uses a modified minus type CCII (MCCII−). One of the main advantages of both configurations is their high input impedances; thus, both can be easily cascaded with other VM circuits. Additionally, the use of a grounded capacitor in both circuits provides suitability for integrated circuit (IC) fabrication process. However, both of the proposed circuits need a single passive component matching constraint. Non-ideality analysis is performed for the proposed circuits. Moreover, two quadrature oscillator applications of the proposed filters are given. The behavior of the filters is verified by SPICE simulations. Also, experimental tests using commercially available ICs (AD844s) are achieved for the second proposed configuration.     

Implementation of reconfigurable nth-order filter based on CCII

Topologies for realizing voltage and current mode reconfigurable nth-order filters based on the second-generation current conveyor (CCII) are assessed. The most compatible structure for field-programmable analog array is identified. A CCII adopting active current division networks are utilized for implementing the proposed filter leading to wide control of its coefficients. Programmability characteristics are demonstrated through experimental results obtained from integrated circuit chips fabricated in a 0.18 μm CMOS process.     

Current mode allpass/notch and bandpass filter using single CCII

A current mode second-order allpass notch and bandpass filter using a single CCII, two grounded capacitors and four resistors is proposed. The allpass and notch output current signals, taken out through port z of a CCII and having high output impedance, can be obtained by tuning a resistor in the proposed network. The resonance angular frequency and quality factor of the new network have the advantages of low passive sensitivities and are insensitive to the current tracking error of the nonideal CCII.<>     

A superheterodyne receiver front-end with on-chip automatically Q-tuned notch filters

A superheterodyne receiver front-end with on-chip automatically Q-tuned notch filters is proposed. The front-end includes a differential LNA and a Gilbert down-converter, where each block is coupled with an on-chip image-rejection notch filter to get high image-rejection ratio. Each notch filter is formed by one on-chip LC network and one negative-resistance cross-coupled pair to compensate for the loss of the LC network. The current through the cross-coupled pairs is automatically adjusted by an automatic Q tuning circuit so that the loss of the notch filter is perfectly compensated to achieve a deepest notch. The automatic Q tuning circuit is an analog?Cdigital mixed signal circuit, and successive approximation register algorithm is used to search for the optimum current value. The superheterodyne receiver front-end has been implemented in 0.18???m CMOS. Experimental results show that the circuit could achieve an image rejection ratio of 75?dB with 105?MHz IF Frequency. The LNA draws 5.86?mA current, and the down-converter draws 1.27?mA current while two image-rejection filters and the master VCO totally draw 363???A current, all from a 1.8?V power supply.     

Universal filter with three inputs using CCII+

A voltage-mode universal filter with three inputs and one output using only plus-type current conveyors (CCII+) is presented. This circuit uses three CCII+s, three resistors and a minimum number of capacitors. It has low sensitivity, low output impedance and low component spread. The use of only CCII+s simplifies the configuration     

单电流传输器实现的Q增强二阶带通滤波器

本文提出了几种用单块电流传输器(CCII)实现的Q增强二阶带通滤波电路。这些电路使用的元件较已见报道的同类电路和用运算放大器(OA)实现的同类电路少;适当选择元件参数,还可实现RCD串联谐振器。     

Electronically Tunable Microwave Bandpass Filters

Combline filters with novel input and output coupling networks which enable broad-band tuning to be achieved with minimum degradation in passband performance are discussed. Explicit design formulas for these filters are presented. Computer analysis of varactor tuned combine bandpass filters including the small signal varactor equivalent circuit is presented enabling filter performance to be easily evaluated. The design and experimental performance of a varactor tuned combline filter, realized in suspended substrate stripline is described. This filter toned from 3.2 GHz to 4.9 GHz exhibited low passband insertion loss and its performance was is close agreement with theoretical expectations.     

一种高输入阻抗单CCII电压模式滤波器

提出了一种实现高输入阻抗电压模式滤波器的新电路。该电路使用一个CCII(第二代电流传输器)和最少量的RC元件实现一阶低通、一阶高通及二阶带通滤波器。一阶滤波器仅含3个接地RC元件,二阶滤波器含4个RC元件,其中电容均接地。给出了电路的有源及无源灵敏度及计算机PSPICE仿真结果     

一种面向多标准无线收发器的低功耗宽调谐范围基带滤波器设计

本论文提出了一种面向多标准收发器的具有精确片上调谐电路的低功耗宽调谐范围基带滤波器。设计的滤波器是由三级Active-Gm-RC类型的双二次单元级联组成的六阶巴特沃斯低通滤波器。采用改进的线性化技术来提高低通滤波器的线性度。论文提出了一种新的匹配性能与工艺无关的跨导匹配电路和具有频率补偿的频率调谐电路来增加滤波器的频率响应精度。为了验证设计方法的有效性,采用标准的130nm CMOS工艺对滤波器电路进行流片。测试结果表明设计的低通滤波器带宽调谐范围为0.1MHz-25MHz,频率调谐误差小于2.68%。滤波器在1.2V的电源电压下,功耗为0.52mA到5.25mA,同时取得26.3dBm的带内输入三阶交调点。     

High input impedance voltage-mode universal biquadratic filter using two OTAs and one CCII

A three-input and single-output voltage-mode universal biquadratic filter with high input impedance, using only two operational transconductance amplifiers (OTAs), one plus-type second-generation current conveyor (CCII) and two capacitors, is presented. The proposed circuit can realize all the standard filter responses, that is, highpass, bandpass, lowpass, notch and allpass filters, from the same configuration. The proposed circuit has no requirements for component matching conditions.     

Tunable microwave and millimeter-wave band-pass filters

The authors present an overview of tunable microwave and millimeter-wave bandpass filters realized in different technologies. Some general design principles are described. Recent progress in the performance of various tunable filters is reported. The authors survey magnetically tunable filters (ferrimagnetic resonance filters, magnetostatic-wave filters, evanescent waveguide filters, E-plane printed circuit filters), electronically tunable filters, and mechanically tunable filters. The typical performance parameters are summarized. This comparison shown that none of these devices can simultaneously satisfy all requirements for perfect tunable filters. For microwave systems where multioctave tuning is essential, a YIG filter is an obvious choice. In systems where the requirement of high power handling capability combined with low insertion loss, predominates, mechanically tunable filters and magnetically tunable E-plane filters are recommended. If the tuning speed is a crucial requirement, varactor-tuned filters or E-plane filters with ferrite toroids are devices of choice. For millimeter-wave design, the most promising structures are ferrimagnetic resonance filters utilizing hexagonal ferrite resonators or, up to 60 GHz, magnetically tunable E-plane printed circuit filters     

基于电调谐DOCCII的电流模式连续时间滤波器

本文提出了基于可变电流增益双输出CCII(DOCCII)的电流模式N阶低通滤波器和通用滤波器,并给出了N阶通用滤波器的一个通用表达式。所给出的滤波器参数可以通过DOCCII的可变电流增益因子独立调谐,并且结构简单,所有无源元件均接地,便于集成。     

Transformation of Voltage Mode Filter Circuit Based on Op-Amp to Circuit Based on CCII

In this paper, firstly we demonstrate the use of nodal admittance matrix to convert a low-pass band-pass filter based on operational amplifier (op-amp) to a circuit based on a second-generation current conveyor (CCII). This technique allows us to get eight presumptions of filter circuits. Secondly, we present a novel architecture circuit of CCII, which can operate at low supply voltage of 0.75 V. All simulations are performed by TSPICE models. The simulation results show that this circuit has a low impedance at terminal X (RX=1.01 ), a very high input impedance at terminal Y, and wide bandwidth current and voltage. The center frequency of the proposed filter is variable on the interval[157 kHz, 196 MHz].     

电流模式带通滤波器设计

随着电子技术的发展,电流模式电路也越来越受到人们的关注,尤其是CCII(第二代电流传输器),本文针对以往电路过于复杂的特点,利用CCII(第二代电流传输器)设计基于单个CCII的带通滤波器电路,该电路仅使用一个CCII和几个R,C元件,与同类电路相比,该电路结构简单,且具有更低的无源灵敏度。     

基于近零介电常数超材料的液晶可调带通滤波器设计方法研究

可调带通滤波器是物联网、卫星通信、智能天线等系统中不可缺少的关键器件之一。针对目前对可调带通滤波器小型化、低成本和高集成度等特点的应用需求,提出了一种基于液晶材料的可调带通滤波器设计方法。通过微带传输线结构实现了近零介电常数(epsilon near zero,ENZ)超材料单元结构的设计,并利用ENZ超材料的窄通道隧穿效应有效实现了窄带滤波功能,通过将3个ENZ超材料单元结构串联从而完成了带通滤波器基本结构的设计。在此基础上,将微波液晶材料引入ENZ超材料的隧穿通道中,利用液晶材料在外部驱动电压作用下介电参数可变的特性,最终实现了对带通滤波特性的有效调控。全波数值仿真结果表明,所提出的基于ENZ超材料的液晶带通滤波器能够实现中心频率15.88~16.73 GHz的调控,从而验证了设计方法的有效性。