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The development and design of a bi-directional pulse-current sensor for bi-directional PWM dc–dc converters are presented. The bi-directional sensor consists of functionally two unidirectional sensors. However, instead of using two separate transformers, an integrated magnetic component, which functions as two pulse-current transformers, is used. The z-parameter (gyrator) model and the equivalent-circuit model of the integrated transformer are derived. Based on the equivalent-circuit model, some design criteria of the integrated transformer for the bi-directional pulse-current sensor are described. Simulated and experimental results have proved the usefulness of the bi-directional pulse-current sensor.

An integrable electronically tunable general impedance inverter (EGII), implemented by a MOS circuit design technique, is described. The driving point impedance of the EGII, that is inversely proportional to a given impedance, can be a positive or a negative value and can be electronically varied. The realization scheme employs proposed voltage-to-current transducers (VCTs) that are designed based on a linearizing technique, as basic circuit building blocks. The applications of the EGII as a gyrator, a general impedance converter and a floating capacitance multiplier are discussed. Experimental and simulation results that demonstrate the characteristics of the EGII are included.

An integrated simulated inductor was proposed by Qiu (1991). It was composed of discrete components for use before its realization as a monolithic integrated circuit. But it was a trouble to need so many matched pair transistors. A satisfactory solution is to use ready-made IC four-quadrant analogue multipliers to form the simulated inductor. The present simulated inductor is different from the former in circuit construction and expression form although they are simular in basic principle. Its features make it suitable for practical applications as a circuit element of a sine-wave oscillator or a filter with linear voltage control characteristics in the low or very-low frequency ranges. A typical example is to build a sweep-frequency signal source to determine the frequency response of a linear network working in a very-low frequency range, which has been verified experimentally.

New switched-capacitor (SC) circuit realizations of arbitrary resistive N-ports are described. Two approaches are proposed: the conductance matrix approach, which permits a drastic reduction of the number of active devices, and a more general scattering matrix approach especially suitable for higher-frequency applications. The main features of the proposed procedures are that the elements of the desired matrices can be adjusted exactly and independently from each other, and the number of required operational amplifiers is quite small. Examples are given to illustrate the synthesis procedure. Computer simulations of SC multiterminal gyrators, circulators, multiwinding transformers, impedance inverters and converters are in good agreement with the theory.

It is shown in this paper that a marginally stable two-port network operates as a gyrator. A practical method for indicating this condition is derived from the gyratory property of the immittances observed at input and output ports of the terminated two-port network. This method is very useful for designing analogue integrated circuits, such as active filters.

A basic method for obtaining a stable two-port operation of a gyrator is proposed. It can be applied in a region higher than several MHz. The circuit conditions for the stable twO-port operation are determined by a computer simulation. It is shown by experiments that the stable two–port operation can be realized at frequencies as high as 88 MHz. The present method is very useful for the design of a gyrator resonator in which the circuit parameters depend on the frequency.

By introducing a multivariable form of Tellegen's Theorem and a generalization of energy functions, the positive-real nature of immittance matrices of finite networks composed of resistors, p-plane inductors and capacitors, all non-negative, transformers and gyrators, is proven, us well as the lossless constraint. Multivariable reactance functions are investigated and the relation between such functions and multivariable Hurwitz polynomials is proved.

L-R and C-R mutators are shown to be useful in synthesizing floating inductors. Considering microelectronic realizations the mutator derived inductor is shown to be advantageous over the gyrator in producing high-valued precision inductors.

Various schemes of realizing an inductor have been proposed in the literature, which use active elements other than gyrator and RC elements. They realize either a bilinear RL impedance in a specified frequency range (Borndt and Dutta Roy 1909, Patranabis and Roy 1072, Sankara Rao and Murti 1970, Venkateswaran and Radhakrishna Rao 1070 a, b) or a linear RL impedance (Patranabis 1972, Patranabis and Roy 1972) of a single port. Here is a scheme to realize a bilinear RL impedance, which employs an inverting VCVS of finite gain. The sensitivity figures with reference to the active and passive parameters are seen to be finite and low values.

Numerous circuits have been developed in the past for simulating inductors, using operational amplifiers and other passive components. Although some of these circuits can be shown to have ideally infinite Q factors, in practice the value may be limited by various stray and non-ideal effects. This note presents a modified gyrator circuit, in which the equivalent series resistance can be totally eliminated by simulation of a series negative resistance of equal value in the gyrator, resulting in a very high value of Q.

An appropriately chosen controlled-source, in association with a current-controlled negative resistance, can be used to produce a grounded, high Q, impedance-matrix realization of the gyrator. Details of one such realization are given here.

The conventional approach to active filter design problems using gyrators has been to replace each individual inductor (grounded or ungrounded) of the passive filter by an active network using one or more grounded gyrators. The method fails to realize three terminal versions when the passive filter is itself a balanced one (four-terminal two-port(. Another approach is to replace the passive filter as a whole by an equivalent active network using gyrators. The transfer function as a whole is synthesized as an active network. This method makes possible the realization of three terminal versions of certain active filters which are not possible by the conventional method. The method has been illustrated for the cases of a driving-point impedance function and a constant resistance lattice filter. An all-pass transfer function has been synthesized as an example.

It is shown that a stable, driving point admittance function is synthesizable as an active two-port lossless non-reciprocal network, with a termination of 1 ohm resistance. The active two-port structure consists of two gyrators dud a lossless -π structure. In most of the cases augmentation is not required. The cases when augmentation is required are investigated.

It has been stated as a conjecture (Duinker 1962) that every passive electrical system is equivalent to some network, exclusively containing elements of the set formed by the linear one-port and two-port elements (resistance, inductance, capacitance, transformer and gyrator), supplemented with the conjunetor (Duinker 1962) and the traditor (Duinker 1959). In this paper it is shown that, with a well-designed voltage-controlled current source, the electronic realization of the non-energic elements is feasible. The circuits are presented and some aspects of their performance are mentioned.

A generalized gyrator has been defined by its transmission matrix as: where g1(8) and g2(8) are positive or negative realizable admittance functions. A method of realizing this generalized gyrator has been given. The different gyrators that result, depending on the signs of g1(8) and g2(8), have been classified. As an application it is shown that any arbitrary driving point function may always be synthesized using a generalized gyrator and five RC one-ports.

Uncoupling of feedback-amplifiers results in amplifiers of which the input and output impedance has the same value as from the feedback-amplifier, but with the internal current source depending on the manner of feedback connection, thus complete unilateralization. The same holds for double feedback-amplifiers, such us a gyrator.

It is shown that any arbitrary driving point function can always be realized by an active two-port RC structure terminated in a passive one ohm resistance. The active RC structure essentially consists of two gyrators and three passive RC one porta. The procedure is illustrated by an example. Further, this active RC structure, along with a proper connection of a NIC, will realize any arbitrary Y matrix having simple negative real axis poles.

The principle of operation of the gyrator circulator has been explained with the help of a scattering matrix. It is shown that power flow can take place from port A to B, B to C and so on, i.e. in one particular sequence. It has also been proved that there is no cross coupling of power.