Four-terminal Floating Nullor Research Articles

Universal two-input two-output current-mode active biquad using FTFNs

A universal active biquad using the four-terminal floating nullors (FTFNs) is presented. The proposed circuit uses two FTFNs, two capacitors and two resistors. The proposed circuit has two input currents and can provide two highimpedance output currents. Without changing the circuit topology, the output currents can realize lowpass, highpass, bandpass, and allpass transfer functions. A notch transfer function can be obtained by adding a voltage-to-current converter using an additional FTFN. The proposed circuit enjoys low passive sensitivities and orthogonal tuning of the parameters ωo and ωo/Qo.

Current-Mode Quadrature Sinusoidal Oscillators using two FTFNs

New current-mode quadrature sinusoidal oscillator circuits are obtained from a voltage-mode two-operational-amplifiers based quadrature oscillator circuit by replacing the operational amplifiers by four-terminal floating-nullors (FTFNs). The properties of the resulting oscillators are discussed and the theory is supported by SPICE simulation.

Cascadable current-mode filters using single FTFN

This comment relates to a previously published letter (see M.T. Abuelma'atti, ibid., vol.32, pp.1457-8, 1996) which presents a cascadable universal current-mode second-order filter using a single four-terminal floating nullor (FTFN) with low active and passive sensitivities. In it, the authors suggest an amended expression for the current-transfer function.

High-input impedance filters using FTFNs

High-input impedance bandpass, lowpass, and highpass filters using two fourterminal floating nullors (FTFNs) are presented. Among these filters, the bandpass and lowpass filters require only grounded capacitors which are suitable for monolithic integration. All the proposed high-input impedance filters have active and passive sensitivities no greater than unity. Experimental results are given to verify the theoretical analysis.

Realisation of R-L and C-D immittances using singleFTFN

New resistor–inductor and capacitor-frequency-dependent negative resistance configurations are presented that use one plus-type four-terminal floating nullor (FTFN) and three passive components. The values of simulated elements can be orthogonally adjusted without any matching condition. Simulated results agree well with theoretical values.

Versatile Active Biquad Using FTFNs

A universal active biquad using the four-terminal floating nullors (FTFNs) is presented. The propsed circuit uses two FTFNs, three capacitors and two resistors. The proposed circuit has three input voltages and can simultaneously provide a high-impedance output current and/or an output voltage. Without changing the circuit topology, the output voltage can realise lowpass, highpass, bandpass, notch and allpass transfer functions and the output current can realise bandpass and highpass transfer functions. The proposed circuit enjoys low active and passive sensitivities and independent control of the parametersωoandω0/Q0.

Current-Mode Universal Filter Using FTFNs

A new current-mode universal filter is presented. The proposed filter uses three four-terminal floating nullors (FTFNs), three grounded capacitors, and four grounded resistors. The proposed filter has three inputs and one output and can realize lowpass, highpass, bandpass, notch, and allpass transfer functions without changing the circuit topology. The proposed filter enjoys low active and passive sensitivities and independent control of the parametersω0andω0Q0using grounded elements.

Single-resistance-controlled sinusoidal oscillatorusing two FTFNs

A new single-resistance-controlled sinusoidal oscillator using two four-terminal floating nullors (FTFNs) is presented. The proposed oscillator has good frequency stability, single-element-controlled ability and low passive and active sensitivities. Moreover, this oscillator needs only grounded capacitors and its oscillation frequency can be independently controlled by a grounded resistor. Experimental results are given to verify the theoretical analysis.

Realization of current-mode filters using single FTFN

A new configuration using single four-terminal floating nullor (FTFN) is presented to realize various kinds of current-mode filters. These current-mode filters have high output impedance, so they can be cascaded without additional buffers. The proposed filters in this paper require less passive components than the previous ones (Liu 1995). Moreover, the resultant current-mode filters will be insensitive to the current tracking error of an FTFN. Experimental results confirm that the theoretical analyses are obtained.

Cascadable current-mode filters using single FTFN

A new configuration for realising cascadable current-mode second-order filters using the single four-terminal floating nullor (FTFN) is presented. The proposed realisations have low active and passive sensitivities and use six passive elements at most.

Insensitive current/voltage-mode filters using FTFNs

A new configuration for realising insensitive current/voltage-mode filters using two four-terminal floating nullors (FTFNs) is presented. It can provide the current/voltage-mode filters with reduced sensitivities. Moreover, the current-mode filters can have high output impedance and only grounded capacitors. The proposed universal voltage-mode filter with dual outputs can realise lowpass, bandpass, highpass, notch and allpass filtering functions. Simulation results are given to verify the theoretical analysis.

Cascadable current-mode filters using single FTFN

A new configuration for realising current-mode filters using a single four-terminal floating nullor (FTFN) is presented. It can realise lowpass, bandpass, highpass, notch and allpass filters from the same configuration. This configuration has a high output impedance, so the synthesised current-mode filters can be cascaded without additional buffers. Moreover, the resultant current-mode filters will be insensitive to the current tracking error of an FTFN. Experimental results that confirm the theoretical analyses are obtained.

Current-mode lowpass, bandpass and highpass filters using an FTFN

A novel circuit configuration for realizing second-order lowpass, bandpass and highpass filters in current-mode is presented. The circuit uses a four-terminal floating nullor (FTFN) and four passive elements, and realizes simultaneously two transfer functions (lowpass/bandpass or highpass/bandpass). It is also shown that an FTFN is a more flexible and versatile building block than a current conveyor (CCII).

Current-mode allpass filter using FTFN with grounded capacitor

A novel circuit configuration for the realisation of a current-mode first-order allpass filter using a single four-terminal floating nullor (FTFN) with a grounded capacitor, which is suitable for integrated circuit implementation, is proposed.

Realisation of current-mode transfer function using four-terminal floating nullor

Active-RC synthesis of transfer functions using four-terminal floating nullors (FTFNs) is proposed, and it is shown that an FTFN is a more flexible and all-round building block than an operational amplifier (OA) or a current conveyor (CC II).