Implementation of Chua's circuit using simulated inductance

In this study we describe how to build an inductorless version of the classic Chua's circuit. A suitable inductor for Chua's circuit is often hard to procure. The required inductor for the circuit is designed using simple circuit elements such as resistors, capacitors and operational amplifiers. The complete circuit can be implemented by using off-the-shelf components, and it can readily be integrated on a single chip. This design of Chua's circuit allows the original dynamics to be slowed down to just a few hertz, enabling implementation of sophisticated control schemes without severe time restrictions. Another novel feature of the circuit is that losses associated with capacitors due to leakages can easily be compensated by providing negative resistance using the same setup. The chaotic behaviour of the circuit is verified by PSpice and Multisim simulation and also by experimental study on a circuit breadboard. The results give excellent agreement with each other and with the results of previous investigators.     

Operational differentiation using simulated inductance with single-ended amplifiers

The passive RL form of differentiating circuit is used as a basis for the development of new forms of differentiator, in which the shunt inductance element L is simulated, and the error incurred by the series resistance R is compensated for, by a composite operational-amplifier network. An arrangement that employs only two single-ended operational amplifiers is derived.     

New grounded simulated inductance circuit using a single PFTFN

A new single-PFTFN based lossless grounded inductance simulation circuit has been presented. The proposed circuit employs a single PFTFN along with four resistors and a single capacitor and realises a lossless grounded inductance subject to the fulfillment of only one realization condition. Some sample results of circuits realized with the new simulated inductor using existing CMOS FTFN implementation have been given to demonstrate the workability of the new circuit.     

Active bandpass and bandstop filters using identical networks

Active bandpass and bandstop filters are described using a number of identical circuits, in which the central frequency and relative bandwidth are independently adjustable.     

Active RC single-resistance-controlled lossless floating inductance simulation using single grounded capacitor

A novel CCII-based circuit using a single grounded capacitor for single-resistance-controlled lossless floating inductance simulation is presented.     

Analog wavelet transform using multiple-loop feedback switched-current filters and simulated annealing algorithms

A new approach for implementing continuous wavelet transform (CWT) based on multiple-loop feedback (MLF) switched-current (SI) filters and simulated annealing algorithms (SAA) is presented. First, the approximation function of wavelet bases is performed by employing SAA. This approach allows for the circuit implementation of any other wavelets. Then the wavelet filter whose impulse response is the wavelet approximation function is designed using MLF architectures, which is constructed with SI differentiators and multi-output cascade current source circuits. Finally, the CWT is implemented by controlling the clock frequency of wavelet filter banks. Simulation results of the proposed circuits and the filter banks show the advantages of such new designs.     

Active filters and gain-bandwidth product

For several active-filter configurations employing operational amplifiers, the variation of resonance frequency and Q factor is given as a function of the ratio of the resonance frequency to the gain-bandwidth product of the operational amplifier. Consideration of these equations leads to the choice of the Wien-bridge filter or its equivalents for applications requiring a high Q factor at high frequencies.     

Active Cheby?shev filters

The synthesis technique described below permits active RC realisation of transfer functions of the type K/(anxn+an?1xn?1+an?2xn?2+ ? + a0), where x is the complex transform frequency variable s, or its reciprocal 1/s. This procedure has the advantage that the active devices are nonideal low-gain amplifiers which may be realised quite simply using transistors.     

Oscillating circuit using nonlinear inductance

An oscillating circuit with nonlinear inductance is examined. A general characteristic of an inductance is used. Using the method of Samoilo, expressions for the oscillation frequency, the current harmonics, the characteristics of the forced oscillations and the characteristics of the parametric resonance are obtained, without limitations on the oscillation amplitude.     

Broadband negative group delay networks for compensation ofmicrowave oscillators and filters

The design of distributed broadband negative group delay circuits operating from 3 to 6 GHz with negative group delays of around 50 ps are described. These circuits are designed using LCR prototypes which are then converted to printed transmission line structures. The parameters affecting the value and bandwidth of the group delay are discussed     

High-Q helical resonator for oscillators and filters in mobile communications systems

A high-Q helical resonator is described which is directly coupled and resonant for lengths of approximately lambda /2. This resonator is extremely easy to fabricate, and is used to demonstrate high-Q filtering and low-noise oscillator operation as the resonator in state-of-the-art L-band oscillators.<>     

A thin-film inductance using thermal filaments

A particular thin-film structure is analyzed to determine the conditions for thermal filament formation. Assuming that these conditions are satisfied and that the structure is electrically biased so that a thermal filament exists, the current-voltage characteristic and small-signal equivalent circuit for a general conductivity-temperature characteristic in the thin film are determined. It is shown that an abrupt or discontinuous change in conductivity with temperature of the type observed in materials exhibiting semiconductor-metal transitions is not necessary to obtain thermal filaments. It is also shown that if there is no thermal hysteresis in the conductivity -temperature characteristic of the thin film, the filament equivalent circuit for the particular structure analyzed is closely approximated by a resistance in parallel with an inductance. The thin-film prop. erties required for this inductance to be independent of both the ambient temperature and the bias current are defined. If thermal hysteresis exists, the analysis shows that small-signal distortions occur, the inductance will become frequency dependent at low frequencies, and a nonlinear resistance must be added to the equivalent circuit in series with the inductance. Measurements on this structure using VO2as the thin-film material are presented and discussed, and are shown to verify the conclusions based on the analysis.     

Efficient inductance extraction using circuit-aware techniques

Proposes two practical approaches for on-chip inductance extraction to obtain a highly sparsified and accurate inverse inductance matrix K. Both approaches differ from previous methods in that they use circuit characteristics to obtain a sparse, stable and symmetric K, using the concept of resistance-dominant and inductance-dominant lines. Specifically, they begin by finding inductance-dominant lines and forming initial clusters, followed by heuristically enlarging and/or combining these clusters, with the goal of including only the important inductance terms in the sparsified K matrix. Algorithm 1 permits the influence of the magnetic field of aggressor lines to reach the edge of the chip, while Algorithm 2 works under the simplified assumptions that the supply lines have zero /spl Sigma//sub j/L/sub ij/(dI/sub j//dt) drops (but have nonzero parasitic Rs and Cs) and that currents cannot return through supply lines beyond a user-defined distance. For reasonable designs, Algorithm 1 delivers a sparsification of 97% for delay and oscillation magnitude errors of 10% and 15%, respectively, as compared to Algorithm 2 where the sparsification can reach 99% for the same delay error.     

Active RC filters with differential integrators

A method is described for synthetising active RC filters by using the subtraction property of differential operational amplifiers. The differential operational amplifiers used have infinite gain. The advantages of the filters are simple adjustments, low sensitivities and fewer amplifiers compared with analogue-computer circuits.     

1.1 GHz oscillator using bondwire inductance

Using the parasitic inductance usually associated with a bondwire in an IC package, a bipolar GHz LC-tuned oscillator is designed. Bondwires have very low series resistance and are thus suitable for high-Q applications. Measured results indicate very low phase noise and low power consumption     

Active wavelength-shifting in atomic resonance filters

Active wavelength-shifting is described as a method to expand the number of wavelengths at which atomic resonance filters operate. Optical pumping and exoergic collisional energy transfer are shown to be powerful wavelength-shifting techniques. Expressions have been derived for internal photon conversion efficiency in limiting cases. They are cast in forms that suggest simple branching ratio model equivalents. The photophysical models yield important insights into methods to obtain good photon conversion for even strongly absorbing levels. The results are applied to atomic resonance filters operating at intense Fraunhofer wavelengths     

Novel floating inductance using current conveyors

The letter presents a new ideal floating inductance using second generation current conveyors (CCIIs). The novel feature of this scheme is its realisation with all grounded passive components.     

Quadrature oscillators using CCIIs

Three third-order quadrature oscillators are proposed. Outputs of two sinusoids with 90° phase difference are available in each quadrature oscillator circuit. The oscillation condition and oscillation frequency of each proposed quadrature oscillator are orthogonal controllable. All proposed circuits employ only grounded capacitors. The use of only grounded capacitors is ideal for integration. Experimental results are included to confirm the theoretical analysis.     

Design and evaluation of Feedforward Active ripple filters

An active ripple filter is an electronic circuit that cancels or suppresses the ripple current and electromagnetic interference generated by the power stage of a power converter, thus reducing the passive filtration requirements. This paper explores the design of feedforward active ripple filters for current ripple cancellation, including the design tradeoffs, advantages, and limitations of different implementation methods. The design and performance of an active filter using a novel Rogowski-coil current sensor is discussed in detail. Experimental results from a prototype converter system using this approach are presented, and quantitative comparisons are made between a hybrid passive/active filter and a purely passive filter. It is demonstrated that substantial improvements in filter mass and converter transient performance are achievable using this active ripple filtering method.