Analytical synthesis of general high-order voltage/current transfer functions using CCIIs

This paper proposes two circuit structures to realize general high-order voltage and current transfer functions using second-generation current conveyors (CCIIs). The proposed general high-order voltage/current-mode circuit structures are designed based on an analytical synthesis method. The nth-order voltage-mode transfer function requires 2n+1 CCIIs, 2n+2 grounded resistors and n grounded capacitors. The nth-order current-mode transfer function requires 2n+2 CCIIs, 2n+2 grounded resistors and n grounded capacitors. The voltage-mode third-order allpass, lowpass and highpass filters and the current-mode third-order notch, lowpass and highpass filters that are derived out from the proposed high-order voltage and current-mode circuit structures are simulated to verify the synthesis methods.     

Current-mode multiphase sinusoidal oscillator based on current differencing units

This paper describes the design and experimental verification of a current-mode multiphase sinusoidal oscillator (MSO) employing current differencing units. The oscillator, composed of n 1st-order all-pass sections, generates harmonic current signals with 2n equidistant phase shifts, where n ≥ 2. Compared with conventional MSOs, this circuit is characterized by an extremely simple circuitry and a minimum number of passive and active components. The oscillation condition and the frequency of oscillation are orthogonally controlled. The proposed circuit is suitable for IC fabrication. Experimental verification on an erlier manufactured chip together with a detailed analysis of real influences are included in the paper.     

Electronically tunable current-mode biquad filter employing CCCDTAs and grounded capacitors with low input and high output impedance

In this study, a single-input multiple-outputs current-mode analog biquadratic filter, based on current controlled current differencing transconductance amplifier (CCCDTA) is presented. The proposed filter uses two CCCDTAs and two grounded capacitors without any external resistors, which is well suited for integrated circuit implementation. The filter simultaneously gives 3 standard transfer functions, namely, lowpass, highpass and bandpass filters with independent control of quality factor and pole frequency by electronic method. By summing of I_HP and L_LP, the notch filter can be also achieved. Moreover, the circuit has low input and high output impedance which would be an ideal choice for cascading in current-mode circuit. The PSPICE simulation results are included verifying the workability of the proposed filter. The given results agree well with the theoretical anticipation.     

电流模式n阶CCCII-C的多输入单输出滤波器设计

该文提出了一种结构简单的基于MCCCII的n阶多输入单输出电流模式滤波器电路。该滤波器电路包含n个有源器件、n个接地电容元件,无需接任何电阻元件,可以产生n阶低通、带通、高通、带阻及全通电流模式滤波。由于仅依靠改变外部输入电流信号的接入数目和方式来实现不同功能的滤波器,而电路内部结构及器件数目不变,所以该电路便于单片集成。文中对滤波器进行了PSPICE模拟。     

General high-order grounded and floating immittance structures using current conveyors

This paper proposes two circuit structures to realize general high-order grounded immittances using current conveyors (CCs). The general high-order floating immittances can also be obtained from the proposed general high-order grounded immittances with some circuit modifications. The proposed immittance structures are designed based on an analytical synthesis method. General nth-order grounded immittance function required 2n + 1 CCs, 2n + 1 grounded resistors and n grounded capacitors. General nth-order floating immittance function required 2n + 2 CCs, 2n + 1 resistors and n grounded capacitors. General high-order voltage-mode and current-mode filters can be easily obtained from the proposed grounded immittances. The voltage-mode third-order allpass, highpass and lowpass filters using the proposed grounded impedances as basic building blocks and a voltage-mode third-order highpass filter using the proposed floating impedance as basic building block are simulated to verify the synthesis method.     

Low component current-mode universal filter

A low component current-conveyor based current-mode universal filter with one input and three outputs is presented. The filter can simultaneously realise lowpass, highpass and bandpass responses. Realisation of notch and allpass responses does not require additional active elements. The proposed circuit enjoys low active and passive sensitivities     

Electronically tunable current-mode biquadratic filter and four-phase quadrature oscillator

This paper presents a current-mode biquadratic filter based on ZC-CFTAs. It employs only three ZC-CFTAs, one resistor and two grounded capacitors. It can simultaneously realize not only highpass and lowpass filtering functions but also two different forms of bandpass ones; one has a pass-band gain of Q, the other, a pass-band gain of unity. Its ω_o and Q can be tuned orthogonally through adjusting bias currents of ZC-CFTAs. Moreover, the proposed circuit can also be modified to be a current controlled four-phase quadrature oscillator with small distortion. Non-ideal analysis and sensitivity analysis are provided. The results of circuit simulations are in agreement with theory.     

Compact VDTA-based current-mode electronically tunable universal filters using grounded capacitors

This paper presents a compact current-mode three-input single-output (TISO) type universal filter. Only one voltage differencing transconductance amplifier (VDTA) and two grounded capacitors are employed in the proposed filter. The circuit can realize lowpass, bandpass, highpass, bandstop and allpass biquadratic filter outputs by connecting the appropriate inputs, and offers electronic control of the natural angular frequency (ω₀) and quality factor (Q) by means of adjusting the transconductance gain of the VDTA. In addition, by slight modification of the proposed scheme, another more useful TISO construction with orthogonal ω₀–Q tuning has been obtained. Both the discussed universal filters have been shown to have low incremental active and passive sensitivities. To demonstrate the performances of the filters and verify the theoretical analysis, computer simulations are accomplished with the PSPICE program.     

Current-Mode Linear Transformation Filters Using Current Mirrors

Novel building blocks for designing high-order current-mode filters by employing current mirrors as the elementary active elements are introduced in this paper. As a design example, a fifth-order elliptic current-mode filter is designed using only grounded capacitors. Simulation results using transistor parameters of a typical CMOS 0.35- technology are in a good agreement with the theoretically expected. A comparison with the corresponding current mirror based filter topologies realized using the leapfrog and the wave techniques has been also performed. For this purpose, new leapfrog and wave filter topologies are introduced. Comparison results confirm the benefits offered by the proposed filter configurations.     

Resistorless realization of current-mode first-order allpass filter using current differencing transconductance amplifiers

This paper presents a realization of a current-mode first-order allpass filter using two current differencing transconductance amplifiers (CDTAs) as the active components and one virtually grounded capacitor as the only passive component. The proposed filer requires no external resistor and is electronically adjustable by varying the external bias current of the CDTA. No component-matching constraints are required. The circuit realizes both inverting and non-inverting types of allpass filters, and also exhibits high-output impedances, which are easy cascading in the current-mode operation. As an application of the proposed CDTA-based allpass section, a current-mode quadrature oscillator is realized. PSPICE simulation results are given to confirm the theoretical analysis.     

Simulation of a novel current-mode universal filter using FDCCIIs

In this paper, a new current-mode universal active-RC filter is proposed. The proposed circuit is based on a new universal passive filter topology. This passive filter is generated from a classical well known current-mode universal passive filter applying a transformation procedure. Two Fully Differential Current Conveyors (FDCCII) are used to construct a universal active-RC filter from this passive filter. The FDCCII based proposed filter has only grounded resistors and capacitors as the passive elements. The circuit simultaneously provides the three basic filter characteristics, namely high-pass (HP), band-pass (BP) and low-pass (LP). SPICE simulation results are given to verify the theoretical analysis.     

Universal current-mode filter with reduced number of active andpassive components

A new current-mode (CM) universal active filter with single-input and three-outputs (SITO) employing only four CCIIs and a minimum number of passive components is presented. The proposed filter based on an RLC shunt circuit, has a good sensitivity performance and achieves the desired filter characteristics without any component matching     

基于单个CDCTA的低压电控调谐电流模式多相位正弦振荡器的设计

提出了一种全新的电流模式多相位正弦振荡器电路。该电路仅使用一个电流差分级联跨导放大器(CDCTA)和接地无源元件,能产生n(n为奇或偶)个等相位差的电流信号,电路结构简单、工作电压低、输出阻抗高、振荡频率高,而且振荡条件和振荡频率独立可调。计算机CADENCE软件仿真和流片测试结果验证了理论分析的正确性。     

Versatile current-mode universal biquadratic filter using DO-CCIIs

In this article, a new three-input and three-output versatile current-mode universal biquadratic filter is proposed. The circuit employs three dual-output current conveyors (DO-CCIIs) as active elements together with three grounded resistors and two grounded capacitors. The proposed configuration exhibits low-input impedance and high-output impedance which is important for easy cascading in the current-mode operations. It can be used as either a single-input and three-output or three-input and two-output circuit. In the operation of single-input and three-output circuit, the lowpass, bandpass and bandreject can be realised simultaneously, while the highpass filtering response can be easily obtained by connecting appropriated output current directly without using addition stages. In the operation of three-input and two-output circuit, all five generic filtering functions can be easily realised by selecting different three input current signals. The filter permits orthogonal controllability of the quality factor and resonance angular frequency, and no component matching conditions or inverting-type input current signals are imposed. All the passive and active sensitivities are low. HSPICE simulation results based on using TSMC 0.18?µm 1P6M CMOS process technology and supply voltages ±0.9?V to verify the theoretical analysis.     

New electronically tunable current-mode universal biquad filter using translinear current conveyors

In this study, a new electronically tunable current-mode universal filter with two inputs and two outputs employing one translinear current conveyor, one translinear current conveyor with controlled current gain and two grounded capacitors is presented. The proposed circuit offers the following attractive features: realisation of low-pass, band-pass, high-pass, band-stop and all-pass current responses from the same configuration; employment of the minimum active and passive components; no requirement of component matching conditions; independent current-control of the parameters natural frequency (ω_o) and quality factor (Q); low active and passive sensitivities; and high impedance output. The characteristics of the proposed circuit are simulated using PSPICE to confirm the theory.     

ICCII-based universal current-mode analog filter employing only grounded passive components

In this paper, three versions of a novel second-order current-mode (CM) single-input three-output analog filter employing inverting second-generation current conveyors (ICCIIs) and only grounded passive components, are presented. This filter can simultaneously realize low-pass, band-pass and high-pass responses, and can also realize notch and all-pass filter responses with interconnection of the relevant output currents. The presented second-order filter requires no active and passive element matching conditions and/or cancellation constraints. The proposed filter offers orthogonal control of angular resonance frequency (ω_o) and quality factor (Q). The proposed filter can realize filter responses at high output impedances, and has low active and passive component sensitivities. Additionally, three versions of a high-order filter derived from the proposed filter are introduced. Simulation results using SPICE program are given to show the performance of the filter and verify the theory. Signal limitations and non-ideal current and voltage gain effects of the proposed second-order filter are also investigated.     

Realisation of nth-order current transfer function employing ECCIIs and application examples

In this article, a universal nth-order current-mode filter employing electronically tunable second-generation current conveyors (ECCIIs) and grounded passive elements is proposed. As the current gain of the ECCII can be controlled electronically by adjusting the ratio of its DC bias currents, it is possible to tune all the coefficients of the transfer function independently. SPICE simulation results using TSMC 0.35 μm CMOS process model are included to verify the theory. Furthermore, a design example of a fourth-order video band filter is given to illustrate the application of the introduced topology in analog circuit design.     

Current-mode differential wave active filters

A technique for obtaining differential active filters suitable for integrated circuit implementation is presented. These filters, based on current-mode differential-wave active blocks, can operate at high frequencies. The cutoff frequency can by tuned by the bias current. The proposed filter topologies are modular and very flexible for both the electronic and the physical design. Simulation results of a third-order elliptic filter, designed in a 0.35-/spl mu/m CMOS technology, are presented.     

Tunable versatile current-mode universal filter based on plus-type DVCCs

This paper presents a new tunable versatile current-mode universal filter with four inputs and three outputs. The proposed configuration employs three plus-type differential voltage current conveyors, two grounded capacitors and three grounded resistors. Its high impedance outputs enable easy cascading in current-mode operation. The circuit can be used as either a single-input and three-output or four-input and two-output. In the operation of single-input and three-output circuit, the bandpass, highpass and bandreject filtering responses can be realized simultaneously. In the operation of four-input and two-output circuit, both inverting and non-inverting type lowpass, bandpass, highpass, bandreject and allpass filtering responses can be simultaneously realized by selecting different four input current signals. The filter permits orthogonal controllability of the quality factor and resonance angular frequency by adjusting the grounded passive components. No component matching condition is required for realizing all the filter responses, and all the passive and active sensitivities are low. HSPICE simulation results based on using TSMC 0.18 μm 1P6M CMOS process technology and supply voltages ±0.9 V to verify the theoretical analysis.     

Multiple-input single-output low-input and high-output impedance current-mode biquadratic filter employing five modified CFTAs and only two grounded capacitors

This paper presents a novel current-mode biquadratic filter with three inputs and a single output. The proposed circuit employs five modified current follower transconductance amplifiers (MCFTAs) and only two grounded capacitors. It can realize all five biquadratic filter functions namely: low-pass (LP), band-pass (BP), high-pass (HP), band-stop (BS) and all-pass (AP) at the output terminal by selecting different input current signals, without requiring any parameter-matching conditions or additional circuits. The filter has an orthogonal electronic adjustment of the natural angular frequency ω₀ and the quality factor Q, and it has very low element sensitivities of ω₀ and Q. Moreover, the proposed filter has the feature of high output impedance and low input impedance, and the use of only grounded capacitors makes it convenient for integrated circuit implementation. The performances of the proposed circuit are illustrated by PSPICE simulations, and the results are in good agreement with theoretical analysis.