Dependent Negative Resistance Research Articles

Network transformations for incorporating nonideal simulated immittances in the design of active filters and oscillators

Although the usual methods of designing active filters through the inductance simulation and frequency dependent negative resistor (FDNR) approaches necessarily require active networks capable of simulating ideal inductors and ideal FDNRs, this paper describes network transformations which make it possible to incorporate even nonideal (lossy) simulated inductance and FDNR elements directly into the filter design. It is shown that the use of these transformations leads to novel filter configurations having many advantageous features. The proposed transformations also prove to be important tools for deriving new sinusoidal oscillator configurations which have properties which are not possible with known oscillator circuits and for providing new interpretations and insights into known oscillator circuits. Experimental results are given which confirm the validity of the theory.

Design of an Active Filter for Channel Translating Equipment

Design of an active filter to meet the specific engineering requirements for its application in the channel translating equipment has been described. It uses the concept of super capacitor or frequency dependent negative resistor and its active realization by integrated operational amplifiers and RC network. It has been established that this type of active realization gives far superior performance compared to that of conventional LC filter in low frequency range. This technique is particularly useful for designing higher order active filters of lowpass type amplitude/frequency characteristic. The circuit configuration and the component tolerances are suitable for thick/thin film implementation.

Frequency selectivity using positive impedance converter-type networks

It is shown that positive impedance converter-type networks may be used to realize a driving-point impedance that is ideally a frequency dependent negative resistor. This concept may be used to realize new types of inductorless selective networks. A simple resonant circuit application is discussed.