Current-mode Universal Filter Research Articles

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.

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.

Universal current-mode filter with multiple inputs and one output using MOCCII and MO-CCCA

In this paper, by introducing a current-controlled current amplifier with multi-outputs (MO-CCCA), two new multi-input and single-output (MISO) universal filtering circuits are proposed. Each circuit just contains two second-generation current conveyors with multiple outputs (MOCCIIs), one MO-CCCA and four grounded RC elements. They can realize low-pass, band-pass, high-pass, band-stop and all-pass filtering outputs. The characteristic parameters natural frequency ( ω 0 ) and quality factor ( Q ) can be tuned independently by bias current of MO-CCCA. Compared to other similar circuits, the circuits in this paper have simpler structures and independent tuning characteristics of ω 0 and Q. Moreover, a filter with a high Q can be obtained by adjusting the ratio of MO-CCCA's bias currents.

Low-voltage digitally controlled current differencing buffered amplifier and its application

In this paper, a design of a low-voltage digitally controlled current differencing buffered amplifier (DC-CDBA) is introduced. The realization scheme is through the cascade connection of a current differencing circuit, a current division network (CDN) and a buffered voltage amplifier. To achieve the digital control of the current gain of the circuit, a novel CDN is also proposed. The proposed DC-CDBA can operate with the low supply voltage of ± 1.25 V . PSPICE simulations using standard 0.5 - μ m CMOS process parameters are in agreement with the theory. An application example using the proposed DC-CDBAs as active elements in the realization of the digitally tuned current-mode universal filter is also included.

Universal current-mode filters and parasitic impedance effects on the filter performances

In this letter, two universal current-mode (CM) filters for simultaneously realizing low-pass, band-pass and high-pass characteristics are proposed. Both of the presented filters can also realize n...

Signal limitations of the current-mode filters employing current conveyors

It is well known that second-generation current conveyors (CCII) are widely used for the realization of second-order current-mode universal filters. A filter with high-quality factor ( Q ) and gain constant ( K ) suffers from various signal swing restrictions especially at its angular resonance frequency ( ω 0 ) . This is due to the terminal voltages of the CCIIs limited by the power supply voltages and maximum allowable terminal currents of the CCIIs. In this paper, signal limitations of the CCII-based current-mode filters are investigated in detail. A filter example is given to exhibit the signal limitations of a universal current-mode filter. The time-domain and frequency-domain results of the proposed filter are also given to verify the theoretical analysis.

Electronically tunable low-component-count current-mode biquadratic filter using dual-output current followers

In this paper, a realization of a current-controlled three-input single-output current-mode universal biquadratic filter using dual-output current followers (DO-CFs) as active components is described. Based on the use of the current-controlled conveyor working as the DO-CF, the proposed circuit employs only two DO-CFs and two grounded capacitors that provide the advantage of an electronic tuning capability and is of special interest from the IC fabrication point of view. By suitably selecting three input signals, the filter can realize all of the standard biquadratic filtering functions, i.e., lowpass, bandpass, highpass, bandstop and allpass, all at a high impedance output which enables easy cascading in the current-mode operation. The natural angular frequency (ωo) and the bandwidth (BW) of the proposed circuit can be tuned independently and electronically over a wide range by adjusting the external bias currents. In addition, no critical component matching conditions are required for all the filter response realizations, and both active and passive sensitivities are low. PSPICE simulation results are used to confirm the characteristics of the proposed circuit.

Comments on “SITO electronically tunable high output impedance current-mode universal filter”

A comment related to the recently published current-mode universal filter, is given. In this comment, it is claimed that this filter is derived from the previously published one without any significant change.

Electronically Tunable Current-Mode Universal Filter Employing Only Plus-Type Current-Controlled Conveyors and Grounded Capacitors

A new current-mode current-controlled three-input single-output universal filter, which employs only five plus-type second-generation current-controlled current conveyors (CCCIIs) and two grounded capacitors, is presented in this paper. The proposed configuration provides lowpass, bandpass, highpass, bandstop, and allpass current responses at a high impedance terminal, which enables easy cascadability of the circuit. The filter also offers independent electronic control of the natural frequency ωo and the quality factor Q through adjusting of the bias current of the CCCII. Derived analytical expressions for the filter parameter deviations due to CCCII nonidealities are also included. PSPICE simulation results are performed to confirm the theoretical analysis.

Stability problems in universal current-mode filters

Analog circuit designers have usually focused on the design of circuits employing a minimum number of components, occupying less area and dissipating less power. However, some important issues such as signal limitations and especially stability problems of the analog circuits have not received considerable attention in the literature. Hence, the work described in this paper deals with the stability problems of two new current-mode analog filters employing multiple output current controlled conveyors (MOCCCIIs). Toward that end, a single pole model is replaced for each non-ideal current gain of the MOCCCIIs. Both of the novel universal current-mode active-C filters can simultaneously realize low-pass, band-pass and high-pass/notch filter responses. SPICE and MATLAB simulation results are given to verify the theoretical analysis.

A new CMOS electronically tunable current conveyor and its application to current-mode filters

In this paper, a new CMOS high-performance electronically tunable second-generation current conveyor (ECCII) is presented. The current gain of the proposed ECCII can be controlled electronically by adjusting the ratio of dc bias currents of the ECCII. The output terminal of the proposed ECCII has high impedance, which enables easy cascadability. Also, as an application, the proposed ECCII is used for realizing a universal current-mode filter. The filter realizes low-pass, bandpass, and high-pass responses simultaneously. The low-pass response is obtained at high impedance output and its gain can be independently tuned by changing the current gain of the relevant CC. SPICE simulation results using TSMC 0.35-/spl mu/m CMOS process model shows excellent performance for the proposed ECCII. The proposed circuit consumes average power of 6.6 mW using /spl plusmn/1.5-V supply voltages.

High output impedance current-mode universal filter employing dual-output current-controlled conveyors and grounded capacitors

A novel current-controlled two-input three-output current-mode universal filter, which employs only three dual-output controlled-controlled current conveyors (DOCCCIIs) and two grounded capacitors, is presented in this paper. The proposed configuration provides inverting-type lowpass, noninverting-type lowpass, inverting-type bandpass, noninverting-type bandpass, highpass, bandstop and allpass current responses at a high impedance terminal, which enable easy cascadability. The filter also offers an independent electronic control of the natural frequency ω o and the parameter ω o / Q through adjusting the bias current of the DOCCCII. No critical matching condition is required for realizing all the filter responses, and all the incremental parameter sensitivities are low. The performances of the proposed circuit are simulated with PSPICE to confirm the presented theory.

Multiple-input single-output current-mode multifunction filter using current differencing transconductance amplifiers

A novel current-controlled multiple-input single-output current-mode universal filter employing current differencing transconductance amplifiers (CDTAs) as active elements is described. The proposed circuit offers the following attractive features: employment of the minimum number of active and passive components; simultaneous realization of all the standard filtering functions; independent current-control of the parameters ω o and ω o / Q ; no requirement of component matching conditions; employment of only two grounded passive capacitors which is suitable for integrated circuit (IC) implementation; and low passive and active sensitivities. PSPICE simulation results are given to verify the theoretical analysis. An example application using the proposed circuit in cascade realization of the high-order current-mode filter is also presented.

Cascadable multiple-input single-output current-mode universal filter based on current differencing buffered amplifiers

Cascadable multiple-input single-output current-mode universal filter based on current differencing buffered amplifiers

A novel current controlled current mode universal filter: SITO approach

A novel electronically tunable single-input three-output (SITO) universal filter employing three current controlled conveyors and two grounded capacitors is presented. The proposed filter offers the following advantageous features: low input impedance and high output impedance- a desirable property of current mode filters, realization of low pass, band pass, high pass, notch and all pass signals from the same configuration, no matching constraint, low sensitivity performance and use of grounded capacitors ideal for integration. The validity of the proposed filter is verified through PSPICE simulations.

Realization of Voltage and Current Mode KHN Biquads Using CCCIIs

Summary In this work, new Kerwin-Huelsman-Newcomb (KHN) biquads employing current-controlled current conveyors (CCCIIs) in voltage-mode (VM) as well as in current-mode (CM) are presented. The parameters of the proposed circuits can be electronically controlled thanks to the tunability properties of the CCCIIs. The VM circuit is derived from a previously reported one by modifying its summing circuit and replacing the current conveyor(CCIIs) and resistors at their x-input terminals with CCCIIs. On the other hand, the CM circuit is derived from the adjoint graph of the signal-flow graph corresponding to the classical KHN circuit. This circuit is a multi-input single-output CM universal filter, which offers all the main advantages of the CM circuits as well as those of the classical KHN circuit. In addition to the three basic filter responses, they also allow the realization of the notch and the all pass responses.

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.

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.

Insensitive current-mode universal filter using dual output current conveyors

A new current-mode universal filter with single input and three outputs employing only three dual output current conveyors and five grounded passive elements is presented. The proposed filter realizes three filter functions simultaneously, all at high impedance outputs. No component matching is required and all the passive and active sensitivities are low. Furthermore, the filter can also realize the notch and all-pass responses. Orthogonal control of the natural angular frequency and the quality factor is achieved.

First-order allpass sections-based current-mode universal filter using ICCIIs

An inverting type current conveyor (ICCII) is presented and its usefulness in active filter synthesis illustrated by presenting a new current-mode universal filter using this element. The universal filter configuration based on the implementation of first-order allpass sections employs the absolute minimum number of passive and active components and hence leads to a filter circuit with very simple implementation.