Current‐Mode Electronically Tunable Universal Filter Using Only Plus‐Type Current Controlled Conveyors and Grounded Capacitors

In this paper we present a new current‐mode electronically tunable universal filter using only plus‐type current controlled conveyors (CCCII+s) and grounded capacitors. The proposed circuit can simultaneously realize lowpass, bandpass, and highpass filter functions—all at high impedance outputs. The realization of a notch response does not require additional active elements. The circuit enjoys an independent current control of parameters ω₀ and ω₀ / Q. No element matching conditions are imposed. Both its active and passive sensitivities are low.     

Versatile multifunction universal voltage-mode biquadratic filter

A new versatile multifunction universal biquadratic filter with four inputs and four outputs employing one differential difference current conveyor, one full differential current conveyor, two grounded capacitors and two grounded resistors is proposed. The proposed configuration can be used as either three-input single-output voltage-mode universal filter with high-input and low-output impedance or single-input four-output voltage-mode multifunction filter with high-input impedance. It still maintains the following advantages: (i) the employment of only two current conveyors, (ii) the employment of only grounded capacitors, (iii) the employment of only grounded resistors, (iv) no need to employ inverting type input signals, (v) no need to impose component choice conditions to realize specific filtering functions and (vi) low active and passive sensitivity performances.     

The inverting second generation current conveyors as universal building blocks

The inverting second generation current conveyor ICCII includes two types. This paper concentrates on the two new types of the inverting current conveyor namely ICCII+ and ICCII-. Although it may seem that there is only minor difference between the two types, there is a significant difference as will be evident from some applications considered in this paper. Both the ICCII+ and the ICCII- are universal building blocks as will be demonstrated in this paper.     

CCII-Based Continuous-Time Current-Mode Biquad Filter

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Universal voltage-mode filter using only plus-type DDCCs

Despite the extensive literature on current conveyor-based voltage-mode universal biquads with single input and multiple outputs, no filter circuit has been reported to simultaneously achieve all of the advantageous features: (i) employment of only two differential difference current conveyor (DDCC), (ii) employment only two grounded capacitors, (iii) employment only three resistors, (iv) simultaneously realize voltage-mode low-pass, band-pass, high-pass, notch and all-pass filter signals from the five output terminals, respectively, (v) orthogonal control of ω _o and Q, (vi) low input impedance and can be cascadable (vii) no need to employ inverting type input signals, and (viii) no need to impose component choice except realizing the all-pass filter signal.     

一种新型通用有源电流模式滤波器的设计

在建立了MOS场效应管小信号模型的基础上,采用信号流图的方法设计了一个三输入一输出的二阶通用有源电流模式滤波器。该滤波器能够通过合理的选择输入电流实现不同的滤波功能,并可通过改变滤波器电路的工作条件来实现不同参数的滤波。推导出这种结构的滤波器具有低灵敏度的特性,总结了这种结构的滤波器的优缺点。     

Current-Mode Universal Filters Using Current Conveyors: Classification and Review

Several current-mode universal filters are reviewed. The filters are classified in two classes. The class I filters have floating passive elements, whereas class II filters have all resistors and capacitors grounded. Each class of filters includes two subclasses based on the filter’s capability to have independent control of the filter quality factor or not. The effects of nonideal second generation current conveyors are briefly discussed. Spice simulations using BSIM3 version 3.1 parameters, feature size 0.5 μm from MOSIS, are given, and a detailed comparison table is included.     

New Universal Filter with One Input and Five Outputs Using Current-Feedback Amplifiers

A new universal voltage-mode second-order filter circuit is presented. The circuit uses five current-feedback operational amplifiers, two grounded capacitors three grounded resistors and three floating resistors. The circuit can realize all the standard filter functions; lowpass, highpass, bandpass, notch and allpass, without changing the passive elements. The proposed circuit enjoys independent grounded-resistance-control of the natural frequency and the bandwidth, low output impedances, high input impedance as well as low active and passive sensitivities.     

High Output Impedance Current-Mode Four-Function Filter with Reduced Number of Active and Passive Elements Using the Dual Output Current Conveyor

This paper reports a new single-input multi-output current-mode multifunction filter which can simultaneously realise LP, HP, BP and BR filter functions all at high impedance outputs. The circuit permits orthogonal adjustment of quality factor Q and ₀, employs only five grounded passive components and no element matching conditions are imposed. A second order all-pass function can easily be obtained. The passive sensitivities are shown to be low.     

Voltage/Current-Mode Universal Filter Using FTFN and CFA

A novel configuration for realizing voltage/current-mode (VM/CM) universal filter using a single four terminal floating nullor (FTFN), a single current feedback amplifier (CFA), two capacitors and three resistors is presented. The VM configuration has three inputs and a single output and implements all the five generic filtering functions through the selection of inputs. This topology enjoys cascadability and does not require any additional active element for facilitating the filter realizations. The same circuit in current-mode has a single input and four outputs and realizes LP, HP and two BP responses simultaneously from which AP and Notch can also be realized. This topology uses grounded resistors and capacitors which are ideal for monolithic integration. Both the topologies enjoy orthogonal control of natural frequency (ω₀) and quality factor (Q) by the grounded resistors. The topologies enjoy low active and passive sensitivity figures. Experimental and PSPICE simulation results are also included.     

Analog Universal Active Device: Theory, Design and Applications

This paper introduces the concept of what we call analogUniversal Active Device (UAD), as a step forward from OperationalAmplifiers and other recently proposed active devices. The modelfor such a device is nothing but a two port classically knownas Nullor. To obtain practical implementations of the UAD, orNullor, a unified aproach is proposed. The basis of the approachis the use of a single cell consisting of a voltage and currentbuffer, also known as negative second-generation Current Conveyor(CCII –). We obtained the four most simple implementationsfor the UAD as a paradigm of more complex ones. Non ideal effectsof these practical implementations are theoretically analysed,particularly parasitic impedances associated to the interconnectionsof the CCII – cells, and then their influence insome simple amplifier stages. It is demonstrated that while anyUAD implementation can be used in a given application, its performanceis strongly dependent on its implementation. Also, a novel floatingstructure for a General Impedance Converter (GIC) type impedance,containing two UADs, is suggested. Simulation results are givensupporting the ideas presented here.     

A new electronically tunable phase shifter employing current-controlled current conveyors

A new canonical current-mode (CM) filter topology is presented. It realizes first-order allpass filtering functions using two dual-output current-controlled current conveyors (DO-CCCII) and a single capacitor. The topology gives both inverting and non-inverting types of these filters. Owing to electronically tunability properties of the CCCII, phase response of the circuit can be controlled by an external control current. Realization of the allpass filter imposes no matching condition. All outputs of the filters exhibit high output impedances so that this property makes the circuits very attractive from the viewpoint of cascading in current mode. The theoretical results are verified with PSPICE simulations using a BJT realization of CCCII.     

Realization of Series and Parallel R-L and C-D Impedances Using Single Differential Voltage Current Conveyor

In this paper, realization of series and parallel R-L immitances using differential voltage current conveyor (DVCC) is presented. The proposed circuits enable actively simulation series and parallel R-L and (-R)-(-L) immitances. Applying RC:CR transformation to the proposed configurations, series and parallel C-D and (-C)-(-D) simulators can also be realized with the same topology. They employ single DVCC and at most three resistors and one capacitor. No component matching constraints are imposed for the realisations. The performance of the proposed immittance simulators is demonstrated on both a second-order voltage and second-order current-mode filters. PSPICE simulations are given to verify the theoretical analysis. An erratum to this article is available at .     

Realization of Universal Active Complex Filter Using CCIIs and CFCCIIs

In this paper, two universal building blocks for complex filter using CCIIs, CFCCIIs, grounded resistors and grounded capacitors are presented. These can be used to realize various complex bandpass filters with arbitrary order. The paper shows that the response error of the proposed circuit caused by nonideality of active components is more easily compensated than that of the conventional one employing op-amps, and that the sensitivities for all components are relatively small. Experimental results are used for verifying the validity of the proposed circuits.     

模型法与分离塞入比法的改进

本文介绍了模型法与分离塞入比法由于采用了模拟电路，而具有的缺点。提出了改进模型法与改进分离塞入比法，可以利用全数字电路实现。同时，文章分析了改进模型法与改进分离塞入比法的性能，以说明它们克服了原方法的不足，而又保持了原方法的优良性能，并给出了对比实验结果。     

新颖的电压模式通用双二阶滤波器

提出了采用第二代电流传送器构成的电压模式三输入、单输出多功能通用双二阶滤波电路,该电路通过选择不同的输入信号,可在输出端得到电压模式二阶低通、高通、带通、陷波和全通五种滤波功能。每种滤波功能的滤波器的固有角频率ωｐ和品质因素Ｑｐ可实现正交调节,所有滤波器都具有低的无源和有源灵敏度。     

SITO electronically tunable high output impedance current-mode universal filter

A novel current-mode (CM) single-input and three-output (SITO) universal filter using two second generation current controlled conveyors (CCCIIs), one current follower (CF) and two capacitors is presented. The circuit is fully programmable and implements all the five generic filtering functions. The lowpass (LP), bandpass (BP), and highpass (HP) functions can be realized simultaneously while Notch (BS) and allpass (AP) responses can be implemented simply by connecting the appropriate node currents without requiring additional elements. The availability of currents at high impedances, facilitate cascadibility feature. The filter performance factors ω₀ and ω₀/Q are electronically tunable through separate bias currents of the CCCIIs. SPICE simulation results are included to confirm the workability of the proposed circuit.     

Current-controllable fully-integrated inductor simulator using CCCIIs

A novel current controllable floating or grounded inductor simulator circuit with minimum elements is proposed. The circuit uses two dual output- second generation current controlled conveyors (DO-CCCIIs) with parasitic resistance at terminal X and one grounded capacitor externally connected. Proposed circuit is suitable for fully integrated circuit design. Analysis and simulation results are included.     

A New CMOS Programmable Balanced Output Transconductor and Application to a Mixed Mode Universal Filter Suitable for VLSI

A new CMOS programmable balanced output transconductor (BOTA) is introduced. The BOTA is a useful block for continuous-time analog signal processing. A new CMOS realization based on MOS transistors operating in the saturation region is given. Application of the BOTA in realizing a mixed mode universal filter using six BOTAs and two grounded capacitors is also introduced. The filter's gain can be adjusted simply by varying the amplitude of a transconductance through its control voltage without affecting ₀ and Q of the filter. Also, the Q of the filter can be adjusted by a single transconductor independent of ₀. PSpice simulation results for the BOTA circuit and for the universal filter are also given.     

Analog Circuit Synthesis Using Linear and Nonlinear Current Amplifiers

Various design techniques are presented for obtaining current-mode filters suitable for operation at high frequencies. For this purpose CMOS and or bipolar current amplifiers are used as active building blocks. The derived circuits simulate LC passive prototype filters. Second order resonators can also be obtained by following the same techniques. The presented circuits are modular in structure, thus, their electronic and layout design is very easy. Low-voltage, low-power design is also feasible. Simulation examples for all-pole filters and filters with transmission zeros are given. George Souliotis received the B.Sc. degree in physics from the University of Ioannina, Ioannina, Greece, in 1993 and the M.Sc. and Ph.D. degrees in electronics from the University of Patras, Patras, Greece, in 1998 and 2003, respectively. From 2000 to 2002, he was with Giga Hellas, an Intel company, designing high-speed electronic circuits for transceivers for optical networks. He is co-inventor of a patent that was developed through that work. He is currently a Post-Doctoral Researcher with the Electronics Laboratory, Department of Physics, University of Patras, Patras, Greece. His research interests include analog and mixed signal integrated circuits for high-speed communication applications, current mode circuits, continuous time active filters and CMOS-BiCMOS VLSI design. Nikos Fragoulis was born in Megara Attikis, Greece, in 1972. He received the B.S. degree in physics and the M.Sc. degree in electronics and Ph.D. in electronics from the Electronics Laboratory, Department of Physics, University of Patras, Patras, Greece, in 1995, 1998 and 2005 respectively. He is currently a post-doctoral researcher with the Electronics Laboratory, Department of Physics, University of Patras, Patras Greece. His research interests include, continuous time filtering, and analog integrated circuits for broadband telecommunication applications. Ioannis Haritantis received the Ph.D. in Electronics, in 1976, from the Physics Department, University of Patras, Patras, Greece, in collaboration with the Electrical Engineering Department, Imperial College, London, UK. For many years he has conducted scientific research on the development and design of circuits, discrete component and/or integrated, which are suitable for analog signal processing. His other fields of interest include, network theory, design and testing of integrated circuits, integrated active devices for telecommunications and medical instrumentation, smart sensors, and e-learning. During the past few years his focus is on the design of low-power, low-voltage, tunable, integrated active filters of high dynamic range that could operate at high frequencies. Professor Haritantis in now the director of the Electronics Laboratory, Division of Electronics and Computers, Department of Physics, University of Patras, Patras, Greece. He is also in the editorial board of the journal “Analog Integrated Circuits and Signal Processing”, Kluwer Academic Publishers.