Nullator

About: Nullator is a research topic. Over the lifetime, 65 publications have been published within this topic receiving 1216 citations.

Inverting second generation current conveyors: the missing building blocks, CMOS realizations and applications

Abstract: The concept of voltage mirror is introduced and used, together with the current mirror, to ideally represent the current and voltage inverting properties of some analogue building blocks. The properties of the nullor and mirror elements are used to relate the different devices in the ideal case as well as to define the adjoint network for each building block. Two new types of second generation current conveyor (CCII) are introduced. One is the adjoint of the CCII+ and is named the inverting second generation current conveyor ‘negative’ (ICCII–); the other is the ICCII+. CMOS realizations of the ICCII– are presented and new ICCII– based current mode circuits are obtained by applying a voltage-to-current-mode transformation to the CCII+ based circuits.

Singular Network Elements

Abstract: The properties of n -ports can be examined in terms of simple properties of linear vector spaces. This approach leads to a very general type of network formalism which in turn casts light on the physical realizability (or nonrealizability) of the singular linear network elements: the nullator (simultaneously an open and a short circuit), and the norator (the unique nonreciprocal one-port with arbitrary port voltage and current). Furthermore, a two-port (the "nullor") which combines these two elements can be shown to be a unique active building block which exhibits the extraordinary nature of the two singular one-ports, but which has other properties which make it amenable for use in practical systems.

Network Synthesis with Negative Resistors

Abstract: The development of new solid-state active elements, such as variable-capacitor diodes and tunnel diodes, has stimulated the network theorist to consider the negative resistor as an additional basic circuit element to be included in problems of linear network analysis and synthesis. In this paper it is first shown that if the negative resistor is added to the usual set of lumped passive building blocks, then it is possible to represent as a network any linear relation between n-port voltages and currents prescribed in terms of real, rational functions of a complex-frequency variable. This leads to the synthesis of some novel pathologic circuits which have neither immittance nor scattering representations, such as a one-port, which is simultaneously an open circuit and a short circuit (v=i=0, the "nullator"), and the linear network in which voltages and currents at the ports are completely arbitrary (the "norator," the unique, linear nonreciprocal, one-port). These elements are shown to be basic linear circuit building blocks. The second part of the paper considers the synthesis in the frequency domain of a real, rational n×n immitance matrix in which pole locations and pole multiplicities are completely arbitrary. It is shown that such a matrix can always be realized with lossless elements and at most n positive and n negative resistors.

Use of Mirror Elements in the Active Device Synthesis by Admittance Matrix Expansion

Abstract: This paper proposes a modification for the symbolic synthesis method of analog circuits using admittance matrix expansion. The modification involves a generalization of the synthesis approach to employ mirror elements (voltage mirrors and current mirrors) in the admittance matrix expansion and ideal description of active elements, rather than using only nullor elements (nullators and norators). Accordingly, more alternative ideal representations, based on nullor-mirror elements, can be realized and a wide range of active elements can be used in the circuit synthesis. Systematic synthesis of the CCII-based generalized impedance converters (GICs) is presented as an application example to illustrate the potential of this generalized approach. Multiple equivalent nullor-mirror realizations for the GIC could be extracted easily, by virtue of using mirror elements in the admittance matrix expansion. Consequently, numerous circuit realizations, spanning various combinations of CCII types, have been generated in a simple and direct way.

On the Voltage Mirrors and the Current Mirrors

Abstract: The voltage mirror and the current mirror are two pathological elements used to represent active devices featuring voltage or current reversing properties. The properties of these ideal elements are presented and it is demonstrated that they form a complete set analogous to that formed by the nullator and the norator.