Novel universal current-mode filters using unity-gain cells

Two novel universal current-mode filters using unity-gain current followers (CFs) and voltage followers (VFs) are presented. The first one, employing three CFs, one VF, two grounded capacitors and two resistors, has two inputs and three outputs. The second one, employing only two CFs, one VF, two grounded capacitors and two resistors, has four inputs and a single output. Both proposed circuits oOEer the following advantageous features: universal current-mode filter realization from the same configuration, no requirements of component matching conditions, employment of two grounded capacitors ideal for integration, employment of two virtually grounded resistors good for voltage control, easy adjustment of ω₀/Q and ω₀ through separate virtually grounded resistors and low active and passive sensitivity performance.     

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.     

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.     

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.     

CDTA based universal transadmittance filter

A new transadmittance-mode (TM) universal filter with three inputs and a single output is presented. The circuit employs only two current differencing transconductance amplifiers (CDTAs), two capacitors one of which is permanently grounded and as many resistors. The proposed circuit realizes lowpass (LP), highpass (HP), bandpass (BP), notch and allpass (AP) functions from the same configuration. Both the active and passive sensitivities are no more than unity. The natural frequency ω_o and bandwidth ω_o/Q are independently and electronically tunable. PSPICE simulation results are included.     

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.     

Single FDCCII-based mixed-mode biquad filter with eight outputs

The transconductance and the transresistance modes might act as the bridge transferring from voltage-mode to current-mode and vice versa, respectively. A novel mixed-mode (including voltage, current, transconductance, and transresistance modes) biquad filter with one input and seven outputs or two inputs and eight outputs is presented. The proposed filter structure only uses a single fully differential current conveyor (FDCCII), three resistors and two grounded capacitors, which are the least components necessary for realizing voltage, current, transresistance modes all five standard filter functions and transconductance-mode band-pass, high-pass filter functions from eight output terminals. Moreover, the new mixed-mode biquad filter still enjoys (i) the employment of two grounded capacitors (attractive for absorbing shunt parasitic capacitance and ideal for IC implementation), (ii) orthogonal control of ω₀ and Q (easy for tunability), and (iii) high output impedance of three current outputs (good for cascadability). H-Spice simulation results verify the theoretical analysis.     

New current-mode current-controlled universal filter with single input and three outputs

In this study, a new current-mode current-controlled universal filter with single input and three outputs is presented. The proposed circuit uses single-output current controlled conveyors (CCCIIs) and can simultaneously realize lowpass, bandpass and highpass filter functions all at high impedance outputs. Realization of notch and allpass responses does not require additional active elements. The circuit enjoys independent current-control of the parameters ω₀ and ω₀/Q without disturbing the gains of the lowpass, bandpass and highpass filters. Both its active and passive sensitivities are low.     

Insensitive current-mode universal filter with minimum componentsusing dual-output current conveyors

A novel universal current-mode active filter with four inputs and one output is presented, which contains only three dual-output current conveyors. Two grounded capacitors and two grounded resistors. The circuit is very advantageous from an integration point of view. The proposed active filter realises all filter responses without any matching conditions at high impedance output and has low passive and active sensitivities     

Novel current-mode biquadratic circuit using only plus type DO-DVCCs and grounded passive components

This paper introduces a novel current-mode biquadratic circuit using plus type differential voltage current conveyors (DVCCs) and grounded passive components. The circuit is constructed with two plus type dual current output DVCCs (DO-DVCCs), two grounded capacitors and two resistors. The circuit can realize multiple circuit transfer functions by choosing the appropriate input and output terminals. Additionally, the circuit parameters Q and ω ₀ can be set orthogonally by adjusting the passive components. The biquadratic circuit enjoys very low sensitivities to the circuit components. An example is given together with simulated results by PSPICE.     

A Versatile Universal Capacitor‐Grounded Voltage‐Mode Filter Using DVCCs

In this paper, a versatile three‐input five‐output universal capacitor‐grounded voltage‐mode filter is proposed. The circuit employs two differential voltage current conveyors as active elements together with two grounded capacitors and four resistors as passive elements. The proposed configuration can be used as either a single‐input five‐output or three‐input two‐output. Unlike the previously reported works, it can simultaneously realize five different generic filtering signals: lowpass, bandpass, highpass, bandreject, and allpass. It still maintains the following advantages: (i) the employment of all grounded capacitors, (ii) no need to employ inverting‐type input signals, (iii) no need to impose component choice, (iv) orthogonal control of the resonance angular frequency ω_o and the quality factor Q, and (v) low active and passive sensitivity performances.     

New FTFN-based grounded-capacitor SRCO with explicit current-mode output and reduced number of resistors

A new current-mode single-resistance-controlled-oscillator (SRCO) using two four-terminal-floating-nullors (FTFNs) is presented. The proposed SRCO provides the following advantageous features, not available simultaneously in any of the FTFN-based grounded-capacitor (GC) SRCOs known earlier so far: (i) use of two GCs which are attractive for IC implementation as well as eliminating/accommodating parasitic capacitances, (ii) very good frequency stability, (iii) low active and passive sensitivities, (iv) independent single grounded resistor control of oscillation frequency (as well as availability of such a control through a resistor ratio), (v) ready availability of explicit current-mode output, and above all, (vi) employment of a reduced number (only four) of resistors, in contrast to earlier two-FTFN-GC SRCOs requiring six resistors. Experimental results are included which confirm the practicability of the proposed circuit.     

High output impedance current-mode universal biquadratic filters with five inputs using multi-output CCIIs

Three current-mode universal biquadratic filters each with five input terminals and one output terminal are presented. The first proposed circuit uses three multi-output second-generation current conveyors, two grounded capacitors and three resistors. This circuit offers the following advantageous features: orthogonal controllability of resonance angular frequency and quality factor, high output impedance, the versatility to synthesize all standard filter types without component matching condition and using grounded capacitors. The second proposed circuit uses three multi-output second-generation current conveyors, two grounded capacitors and two resistors. This circuit offers the following advantageous features: using minimum passive components, high output impedance, the versatility to synthesize all standard filter types without component matching condition and using grounded capacitors. The third proposed circuit uses three multi-output second-generation current conveyors, two grounded capacitors and three grounded resistors. This circuit offers the following advantageous features: the versatility to synthesize all standard filter types, high output impedance and using only grounded passive components. Each of the proposed circuits can get five kinds of filter functions by using only one current input signal.     

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.     

通用有源电流模式滤波器及其仿真

采用信号流图设计了由两个 OTA和一个 MOCC + / -构成的三输入一输出电流模式二阶滤波器新电路 ,合理选择输入电流可实现低通、高通、带通、带阻及全通滤波功能。所提电路结构简单 ,中心频率ω0 和品质因数 Q独立可调 ,无源元件全部接地 ,滤波器特性参数对无源元件灵敏度低。理论分析和 MOS管级的 PSPICE仿真表明所提电路方案正确     

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.     

A novel mixed-mode current-conveyor-based filter

A new mixed-mode biquad circuit is presented. The circuit uses six single-output plus-type second-generation current-conveyors (CCII+s), a single dual-output CCII+, two grounded capacitors, eight resistors, at least two of them permanently grounded, and can realize lowpass, highpass, bandpass, notch, lowpass notch, highpass notch and allpass responses from the same topology. The circuit can be driven by voltage or current and its output can be voltage or current. The parameters ω₀ and ω₀/Q ₀ enjoy independent electronic tunability. Simulation results are included.     

An integrable temperature-insensitive gm –RC quadrature oscillator

A novel g_m –RC quadrature oscillator using operational transconductance amplifiers (OTAs) and grounded passive elements is proposed. The circuit provides two quadrature outputs of equal magnitude and the oscillation frequency is insensitive to temperature. The oscillation frequency can be linearly and electronically controlled without affecting the condition of oscillation. The active ω₀-sensitivity has been shown to be small. Experimental and simulation results that demonstrate the performance of the proposed oscillator are also included.     

Current-conveyor-based single-element-controlled and current-controlled sinusoidal oscillators

A new single-element-controlled sinusoidal oscillator circuit that incorporates two second generation current conveyors (CCIIs), two grounded capacitors and two resistors is presented and analysed. The circuit is beneficial to monolithic integrated circuit implementation by the use of grounded capacitors. In addition, a new current-controlled sinusoidal oscillator using only two second generation current controlled conveyors (CCCIIs) and two grounded capacitors can be achieved by replacing CCIIs and resistors series at X terminals with CCCIIs. The oscillators provide extremely low passive ω₀-sensitivities and good frequency stability. Moreover, the oscillation frequencies of the CCII-based and the CCCII-based oscillators can be controlled, respectively, by a grounded resistor and by an external bias current. Experimental and SPICE simulation results that confirm the theoretical predictions are given.     

高输出阻抗多功能电流模式双二阶滤波器

提出了一种基于多输出端差动差分电流传送器的多功能电流模式滤波器电路结构。该电路用三个多输出端差动差分电流传送器，五个或四个接地电阻和两个接地电容，同时实现了反相和，或同相带通和低通或带通和高通滤波响应特性。分析并模拟了所提出的滤波器的传递特性，PSPICE仿真结果表明，所提出的电路方案正确有效。电路具有灵敏度低，输出阻抗高，滤波器固有频率ωo和品质因数Q相互独立可调，多功能的优点，适于实现全集成连续时间滤波器。