Four-terminal Floating Nullor Research Articles

New FTFN-Based Tunable Memristor Emulator Circuit and its Mutation to Meminductor and Memcapacitor Emulators

For the first time, a new memristor emulator structure using a single four-terminal floating nullor (FTFN) and a transconductance stage has been presented with tunable circuit configuration. Along with that the circuit requires only a single grounded capacitance and two external MOS transistors to realize both incremental and decremental types of memductance functions. The use of the FTFN block has been demonstrated for the first time to build such a compact memristor emulator, which fully utilizes the employed circuit resources. The wide-band operating frequency range (1 kHz–3 MHz) is another attractive feature of the proposed emulator. Moreover, the mutation of the proposed memristor emulator into meminductor and memcapacitor emulators is also presented by the mutators based on FTFN. All the presented circuits have been tested by performing simulations using PSPICE with 0.18-[Formula: see text]m CMOS technology. The generated simulation results clearly show the ideal nonvolatile nature of the realized memristor, which has also been utilized in an op-amp-based circuit designed to exhibit associative learning phenomena. The proposed FTFN-based memristor has been implemented using commercially available ICs, LM13700, and AD844, and the generated PHL plot is discussed.

An active inductor employing a new four terminal floating nullor transconductance amplifier (FTFNTA)

ABSTRACTIn this scientific study, a new analog active building block named as four terminal floating nullor transconductance amplifier (FTFNTA) is implemented. The FTFNTA design offers a combined essence of both traditional four terminal floating nullor (FTFN) and an operational transconductance amplifier (OTA). The FTFNTA design is extended for the design of a lossless floating and grounded inductor simulator with few passive components. In addition, the performance and usefulness of the proposed inductor topology are also expanded for active filter applications: higher-order Butterworth high-pass filter and current mode multifunction filter. The functionality of the CMOS-based FTFNTA is integrated with a 0.18 µm Taiwan Semiconductor Manufacturing Company (TSMC) CMOS technology. Moreover, the FTFNTA is also realised using the current feedback operational amplifier (CFOA/AD844) and OTA (OTA/CA3080) of a commercially available IC to test the viability of the proposed inductor design. Finally, an application based on the inductor topology and its impedance characteristics are well analysed via PSPICE simulation.

Second Order Universal Filter Using Four Terminal Floating Nullor (FTFN)

In this research paper, a voltage mode second order universal filter using Four Terminal Floating Nullor (FTFN) is presented. The proposed design uses Three Input Single Output (TISO) for the realization of all filter responses namely Low Pass Filter (LPF), High Pass Filter (HPF), Band Pass Filter (BPF), Notch Filter (NF) and All Pass Filter (APF) by using proper input selection. The analog building block, FTFN is simply realized with two commercially available AD844 ICs. The proposed second order universal filter comes with a single FTFN block with four passive components in which no component matching is required for filter realization. The universal filter is well verified using PSPICE simulation. In addition, experimental verification for the second order APF has been performed that confirms the theoretical expectations.

A novel Schmitt trigger and its application using a single four terminal floating nullor (FTFN)

In this research paper, a simple clock wise and counter clock wise Schmitt trigger employing single four terminal floating nullor (FTFN) with two external resistors is presented. The proposed Schmitt trigger avails CMOS based FTFN and it is extended for the application as a square and triangular wave generator, by adding an external capacitor to it. In addition, the proposed waveform generator provides independent tunability of amplitude of square wave by implementing the passive resistors using MOS transistors which make the circuit to be integrated fully. Finally, the verification of the proposed design is verified using PSPICE to justify the theoretical analysis. Also, post layout simulation and the experimental verification using commercially available current feedback operational amplifier named as ICAD844 based implementation for FTFN are included to confirm the reliability of the circuit.

Universal Biquadratic filter with minimum number of Active FTFN

A new three input single output (TISO) biquad filter based on a four terminal floating nullor (FTFN) is presented. The proposed universal filter uses a single FTFN with four passive components which realizes all frequency responses namely, low pass filter (LPF), high pass filter (HPF), band pass filter (BPF), all pass filter (APF) and notch filter (NF) respectively. The proposed structure does not require any component matching and is free from non-ideal behavior. The sensitivity of the proposed filter parameters is found to be less than unity. PSPICE program simulations using commercially available IC AD844 are given to validate the performance of the filter and verify the theory.

Four Input Single Output based third order universal filter using Four Terminal Floating Nullor

This paper presents a Four Input Single Output based third order universal filter that offers all five sections of filter frequency responses with some passive components using active block named as Four Terminal Floating Nullor (FTFN). The design schematic uses two number of Four Terminal Floating Nullor (FTFN) with three numbers of resistors and capacitors each. The proposed universal filter is realised with CMOS implementation of FTFN as well as Current Feedback Operational Amplifier (CFOA) namely IC AD844 for FTFN realisation. The viability of the universal filter circuit is justified with PSPICE simulation that includes both CMOS and AD844 based realization of FTFN. Also theoretical verification is well performed for the sustainability of the proposed circuit along with experimental verification by using IC AD844.

Current/voltage-mode universal filter using FTFNs

A new configuration realizing current/voltage-mode (CM/VM) universal filter using two four terminal floating nullors (FTFN) and four passive components is presented. The current-mode configuration has single input and three outputs and realises simultaneously lowpass (LP), bandpass (BP) and highpass (HP) responses from which allpass (AP) and notch functions can also be implemented. The voltage-mode filter has three inputs and two outputs and can be configured to realise all the five filtering functions. The circuit in current-mode uses grounded capacitors which are ideal for monolithic integration. Besides using a bare minimum number of passive components, the topology enjoys low active and passive sensitivity figures. Experimental and PSPICE simulation results are also included.

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 (?0) 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.

Single FTFN Realization of Current Transfer Functions

The paper reports three different synthesis procedures for realizing a class of current transfer functions of any order with negative real poles using only one four terminal floating nullor (FTFN). Relations for the minimum number of elements required in the three procedures are derived. One of the realizations requires minimum number of elements, and can have all the capacitors grounded and the total capacitance a minimum. Such a realization is very much suitable for fabrication in VLSI. Simulation results obtained on an all-pass filter are in agreement with the theoretical ones.

Voltage-Mode Multifunction Filter using FTFNs

The paper presents a novel voltage-mode (VM) multifunction biquadratic filter configuration using three four terminal floating nullors (FTFNs), three resistors and two capacitors. The circuit can simultaneously provide three different filtering functions in a single structure and it realizes all the standard second-order filtering responses. The natural frequency (ω0 and quality factor (Q) can be orthogonally controlled. The passive sensitivity figures are very small. Experimental and simulated results have been incorporated to verify the theoretical analysis.

High impedance voltage- and current-mode multifunction filters

This paper presents a voltage- and current-mode multifunction filters based on and employing two four-terminal floating nullors (FTFNs) and a single operation transconductance amplifier (OTA). The high-input impedance voltage-mode configuration can simultaneously realize lowpass (LP), bandpass (BP) and notch filtering functions from the same configuration. The circuit employs two grounded capacitors which suits contemporary IC design techniques. The resonance frequency ω 0 and bandwidth ω 0 / Q can be independently tuned while as resonance frequency ω 0 and quality factor Q are orthogonally controllable. The current-mode configuration can simultaneously realize LP and highpass (HP) from which notch filtering signal can also be obtained. The input impedance of the circuit is very low while the output currents are available at very high impedances. The resonance frequency ω 0 and bandwidth ω 0 / Q can be orthogonally tuned. The high impedance of both the topologies in the two modes facilitates easy cascading for higher-order filter construction. Passive sensitivity figures are low. PSPICE simulation results are also included.

Comments on "A CMOS fully balanced four-terminal floating nullor

For original paper see ibid., vol.49, p.413-424 (2002 ). The comments in the present paper state that the four-terminal floating nullor (FTFN) is not more versatile than the CCII, because any circuit can also be realized with CCIIs as the only active elements, and that the FTFN and the CCII are not the only universally versatile elements. There are others, such as operational amplifiers. The authors of the original paper state that the FTFN is not yet commercially available. One counterexample is the MAX 435 by Maxim. There are others as well. None of the commercially available FTFNs have actually been given the name nullor, which may be the reason why few people seem to know of the commercial availability of FTFNs.

Current-Mode Filters—A Tutorial Review

In this tutorial paper, the topic of current-mode signal processing is explored. The various current-mode devices such as OTA (operational Tansconductance amplifier), CC (Current conveyor), Current Feedback operational amplifier (CFOA) and Four Terminal Floating Nullor (FTFN) are introduced. Their utility for realizing first and second order filters and oscillators is also considered.

A CMOS fully balanced four-terminal floating nullor

This paper presents design and implementation of a CMOS fully balanced realization of the four-terminal floating nullor (FTFN). The proposed fully balanced FTFN (FBFTFN) is an essential building block for implementing fully balanced architectures of both voltage and current-mode analog CMOS integrated circuits (ICs). A low-power class AB CMOS realization of the proposed circuit is fabricated in a 1.2-/spl mu/m technology. The proposed circuit has numerous applications. Several applications including fully balanced amplifiers, filters, and sinusoidal oscillators are presented. All proposed design techniques and circuits are experimentally verified.

CMOS FTFN realisation based on translinear cells

A novel CMOS implementation of a four-terminal floating nullor (FTFN) is proposed. The presented FTFN circuit is based on two translinear cells and cascode current mirrors. It provides an alternative solution to differential amplifier-based FTFN circuits. Simulation results show that the proposed circuit is quite suitable for wideband, accurate and wide dynamic range current-mode signal processing. The feasibility of the circuit is tested on a current-mode bandpass filter structure.

A new CMOS realization of a four terminal floating nullor (FTFN)

A novel circuit configuration for the realization of a four terminal floating nullor in CMOS technology is proposed. The circuit proposed combines the advantages of a cascade of common-source and common-gate amplifiers and a floating current source. PSPICE simulations show that the proposed circuit is suitable for wideband, accurate and wide dynamic range current-mode signal processing. The feasibility of the circuit is also tested successfully in a current-mode band-pass filter structure.

Current-Mode High Output Impedance Sinusoidal Oscillator Configuration Employing Single FTFN

In this study, a general current-mode high output impedance sinusoidal oscillator configuration is proposed. The proposed oscillator configuration uses a single four terminal floating nullor (FTFN), two capacitors and five resistors. The oscillator configuration exhibits high output impedance which makes easy to drive loads without using any buffering devices and provide non-interactive control of oscillation condition and oscillation frequency. The proposed topology also yields single frequency oscillators with reduced number of passive components. All of the proposed oscillators permit good frequency stability and exhibit low active and passive sensitivities. Theoretical analysis is verified with experimental results.

Universal current-mode filter using single four-terminal floating nullor

A new configuration for realizing cascadable lowpass, highpass, bandpass allpass, notch, lowpass notch and highpass notch, current-mode second-order filters using a single four-terminal floating nullor (FTFN) is presented. The proposed realizations require less matching and cancellation conditions and enjoy low active and passive sensitivities.

CMOS four terminal floating nullor design using a simple approach

In this study a simple approach for design of four terminal floating nullor (FTFN) is introduced and two new CMOS FTFN topologies are proposed using the approach from suitable CMOS negative current conveyor (CCII−) structures. The performance of the proposed circuits was tested by Pspice computer simulation program. The feasibility of the proposed circuits was shown on a current-mode band-pass filter example constructed using one of the proposed CMOS FTFN circuits. The simulation results are given to confirm the predicted theory.

Realization of voltage/current-mode filters using four-terminal floating nullors

A signal-flow graph synthesis procedure for generating voltage/current-mode filters using four-terminal floating nullors (FTFNs) is presented. Novel networks which realize second-order voltage/current-mode filters are given. For presented circuits the element values are expressed in terms of second-order transfer function coefficients and they have grounded capacitors.