LC Ladder Research Articles

A new AC motor driven by travelling magnetic field excited on LC ladder circuit without its nonlinearity

In three-phase AC motors, three-phase AC voltage system is essential to generate a rotating magnetic field. Three- phase AC motors also require a three-phase inverter for variable speed and torque operation. In general, the number of switching devices used in three-phase inverter is not less than six and decreasing its number is difficult. This paper focuses on an LC ladder circuit consisting of linear inductors and capacitors. This paper presents a new operating method of the AC motor based on a propagating magnetic field. It is successfully excited by connecting one single-phase AC power supply to the end of the LC ladder circuit. The induction motor operated by the presented method produces torque as in general induction motors.

Design of Modified Jacobi Microstrip Lowpass Filter for L-Band Application

In this brief, a design of microstrip lowpass filter with the 1 GHz cutoff frequency is revisited, where a class of modified Jacobi polynomials is used for the filter design. The optimization procedure for these filters includes the passband return loss minimization and the roll-off factor enhancement using the magnitude correction of the transmission coefficient. Mentioned correction is performed by introducing the multiple transmission zeros such that LC ladder prototype filter can be realized symmetrically. Three seventh degree filters for L-band applications are realized and simulated: allpole, with a single and double transmission zeros. It is shown that, among these three stepped impedance lowpass filters realizations, the filter with simple transmission zeros offers the best performance.

An improved design method for even-degree optimum allpole filters with equiripple passband responses

The maximum power transfer between source and load is extremely important in analog signal processing. The main disadvantage of signal processing using the even-degree Chebyshev filter is the impossibility of LC ladder network realization between two equal resistors. Therefore, either the utilization of the ideal transformer or the Chebyshev filter of odd-degree is required to achieve the maximum power transfer. To overcome this limitation, the class of even-degree polynomials with the equiripple behavior, referred to as scaled modified Chebyshev polynomials, can be used as the filter’s characteristic function. Passband ripples of obtained filters can be controlled through an embedded parameter, while normalized half-power frequency is kept equal to unity. Furthermore, these filters can be optimized for the minimum amount of reflected power at the input terminals. In this paper, the optimum modified Chebyshev filters are first compared to the classic Chebyshev filters to show that both filters exhibit similar performances. Second, proposed filters are compared to the Least Square Monotonic (LSM) filters that are optimized by minimizing the area under the characteristic function in the passband. Results of comparison reveal that the proposed even-degree scaled modified Chebyshev filters outperform the LSM filters, as is already proved for the odd-degree filters.

LCラダー回路上で励起される回転磁界を利用した交流モータ駆動法の基礎検討

LCラダー回路上で励起される回転磁界を利用した交流モータ駆動法の基礎検討

Floating/grounded series/parallel R-L, R-C and L-C immittance simulators employing VDTAs and only two grounded passive elements

In this paper, four floating/grounded series and parallel immittance simulator topologies are proposed, utilizing voltage differencing transconductance amplifiers (VDTAs) as useful active devices. Each of the proposed topologies requires only two grounded passive components. The floating series and parallel simulated immittance circuits proposed here require just two VDTAs, whilst the grounded ones require only one. The proposed topologies can simulate R-L, R-C, and L-C immittances in series and parallel. All of the simulated equivalent elements for the realized immittances are orthogonal adjustable. Furthermore, there are no critical element equality criteria required for the desired immittance function realization. The behavior of the proposed VDTA-based immittance simulators is exemplified in LC ladder filter and sinusoidal oscillator applications. To illustrate the simulator's performance, PSPICE simulation and experimental test results are used.

Signal Propagation in Transmission Lines with Losses Using Fibonacci Wave Functions

In this paper, the general model for an infinite LC ladder network using Fibonacci wave functions that were applied to lossless transmission lines will be extended to transmission lines including losses. The general model that was derived from a first order system transfer function representing a simple RC or RL circuit will be used to model and analyze transmission lines presenting losses. The LC ladder network model can be applied to any order for each inductor current with its parasitic rc resistor and for each capacitor voltage with its parasitic rL resistor. The extension of the proposed general model to transmission lines with losses is subject to Heaviside condition for both resistors rc and rL .

Component value calculations in a mixed element ladder network containing series capacitors separated by unit elements

SummaryLossless LC ladder networks have many applications. But at high frequencies, inductor‐free designs are preferred since inductors are heavy and have limited values. An additional reason for not using the inductors (at high frequencies) consists in that the values of very small inductors could be quite imprecise. If LC ladder network is high‐pass type, then parallel inductors must be removed. The resulting network will have only series capacitors, which can be combined as a single series capacitor. But if commensurate transmission lines separate the series capacitors, a high‐pass mixed element network is obtained. In this paper, a procedure is proposed to compute the values of series capacitors and characteristic impedances of the transmission lines in the mixed element ladder network. The usage of the procedure is explained by means of the given example.

Analysis on Multi-Stage LC Ladder Matching Circuits with Complex Terminated LC and CL Circuits

As a mobile phone progresses with the third, fourth, and fifth generations, the frequency bands used in mobile phones are increasing dramatically. RF components for mobile phone terminals correspond to this increasing frequency band. In the case of power amplifier (PA), which is one of the RF components, it is necessary to correspond many frequency bands in one PA. In this case, the wideband of the matching circuit is a typical one of the technical problems of PA. In this study, we focus on two-stage and three-stage connections of LC ladder matching circuits widely applied in PA, and compare them from the viewpoint of broadband. In order to efficiently analyze multi-stage LC-matching circuits, the following two new methods were devised. First, we derived the analysis formula of LC and CL-matching circuits when the termination impedance was extended to a complex number. Second, we derived a condition in which the frequency derivative of the input impedance is zero.

Optimum allpole filters with Chebyshev passband magnitude response

A new kind of the allpole lowpass filter functions with Chebyshev behaviour in the passband is derived by minimizing the passband insertion loss. The ripple parameter ε, commonly used to control the attenuation at the cutoff frequency, in proposed approximation is used as a degree of freedom by which the passband attenuation can be controlled, while keeping the attenuation at the cutoff frequency equal to 3 dB. The approximation method relies on solving the nonlinear equation such that the area under the filter characteristic function in passband is minimized. Obtained filters, called Optimum Chebyshev filters, exhibit minimum insertion loss and maximum cutoff slope. Filter polynomial coefficients and the elements values for the LC ladder implementation are tabulated for filter degrees from 3 to 11.Comparison of the Optimum Chebyshev and Least Square Monotonic filters is also discussed in the paper, since both filters are developed subject to the minimum reflected power in the passband; the first with the equiripple and the second with the staircase (monotonic) behavior in the passband. It is also revealed that the Optimum Chebyshev approximation can be considered as the optimal solution among the class of filters whose passband response is bound to be a staircase.

Self‐sustained solitary waves in a tunnel diode oscillator lattice and their applications in frequency division

SummarySelf‐sustained solitary waves, which propagate in a one‐dimensional lattice of tunnel diode (TD) oscillators, can be effectively applied to frequency division. In this work, it is experimentally observed that the properties of a solitary wave strongly suggest that it is the discretized counterpart of the homoclinic pulse predicted in a quasi‐continuous model of a TD oscillator lattice. Generally, these self‐sustained waves annihilate during a head‐on collision. Owing to this phenomenon, a TD oscillator lattice acts as an efficient frequency divider through its simple connection to an ordinary LC ladder circuit. In this work, both the pair annihilation of pulses and a 2:1 frequency division ratio are successfully observed experimentally.

Feasibility evaluation of new electric motors driven by intrinsic localized mode

Intrinsic localized mode (ILM) has been observed in various physical systems. In particular, electromagnetic ILM has been observed on an LC ladder circuit array. This paper focused on the electromagnetic ILM and aims to evaluate the feasibility of a new electric motor driven by the electromagnetic ILM numerically. First, we propose two types of nonlinear inductors with different geometries, and their magnetic saturation characteristics are clarified from the magnetic field analysis. Second, numerical simulations using the obtained parameters show that the moving velocity of a moving ILM varies with an initial voltage disturbance. Finally, we propose an inductor with permanent magnets placed on a surface of a rotor core, aiming to generate the electromagnetic ILM more efficiently. Numerical simulations show that the behavior of the moving ILM is affected by the rotational speed of the rotor.

A Novel Alternating Magnetic Field Generator Based on the Principle of Lattice Vibration in Crystals

Many researchers have been interested in a special vibrational mode called the intrinsic localized mode (ILM), which was found in solid-state physics. As a practical solution to use ILM, this article proposes a novel method of generating an alternating magnetic field which is completely different from the general three-phase alternating current method. An LC ladder circuit array is introduced to reproduce the ILM in an electrical system. Electromagnetic field analysis using the finite element method reveals that the ILM is able to transmit to the neighboring inductors at a constant velocity.

A broadband RLC matched GaN power amplifier using interposer‐MMIC technology

AbstractIn this article, we report a compact and low‐profile GaN‐based broadband power amplifier using silicon interposer‐MMIC (iMMIC) technology. The iMMIC technology enables a GaN HEMT to be embedded in the silicon substrate, and passive circuit elements such as metal‐insulator‐metal (MIM) capacitors, spiral inductors, and thin film resistors to be implemented on the high‐resistivity silicon (HRS) substrate using standard integrated passive device (IPD) process, so that the final power amplifier is almost indistinguishable from a single GaN MMIC power amplifier. The RLC matched all‐pass network and LC ladder type low‐pass network are employed as the input matching network and output matching network, respectively. The proposed power amplifier has a Psat of 39.1 to 39.2 dBm with a power‐added efficiency (PAE) of 40% to 50.5% in the frequency range of 2.1 to 3.5 GHz under continuous wave (CW) input signal. The proposed iMMIC power amplifier occupies only 9.9 mm2.

Realization of Analog Wavelet Filter Using Hybrid Genetic Algorithm for On-Line Epileptic Event Detection

As the evolution of traditional electroencephalogram (EEG) monitoring unit for epilepsy diagnosis, wearable ambulatory EEG (WAEEG) system transmits EEG data wirelessly, and can be made miniaturized, discrete and social acceptable. To prolong the battery lifetime, analog wavelet filter is used for epileptic event detection in WAEEG system to achieve on-line data reduction. For mapping continuous wavelet transform to analog filter implementation with low-power consumption and high approximation accuracy, this paper proposes a novel approximation method to construct the wavelet base in analog domain, in which the approximation process in frequency domain is considered as an optimization problem by building a mathematical model with only one term in the numerator. The hybrid genetic algorithm consisting of genetic algorithm and quasi-Newton method is employed to find the globally optimum solution, taking required stability into account. Experiment results show that the proposed method can give a stable analog wavelet base with simple structure and higher approximation accuracy compared with existing method, leading to a better spike detection accuracy. The fourth-order Marr wavelet filter is designed as an example using Gm-C filter structure based on LC ladder simulation, whose power consumption is only 33.4 pW at 2.1Hz. Simulation results show that the design method can be used to facilitate low power and small volume implementation of on-line epileptic event detector.

Synthesis-Free Trap Exchanges for LC Ladder Networks

Synthesis-Free Trap Exchanges for LC Ladder Networks

Signal Propagation in Nth LC Ladder Network Using Fibonacci Wave Functions

In this paper, new general model for an infinite LC ladder network using Fibonacci wave functions (FWF) is introduced. This general model is derived from a first order resistive-capacitive (RC) or resistive-inductive (RL) circuit. The order Fibonacci wave function of an LC ladder denominator and numerator coefficients are determined from Pascal’s triangle new general form. The coefficients follow specific distribution pattern with respect to the golden ratio. The LC ladder network model can be developed to any order for each inductor current or flux and for each capacitor voltage or charge. Based on this new proposed method, nth order FWF general models were created and their signal propagation behaviors were compared with nth order RC and LC electrical circuits modeled with Matlab-Simulink. These models can be used to represent and analyze lossless transmission lines and other applications such as particles interaction behavior in quantum mechanics, sound propagation model.

Optimized analysis of sharpening characteristics of a compact RF pulse source based on a gyro-magnetic nonlinear transmission line for ultrawideband electromagnetic pulse application

We constructed a compact high-power RF pulse generator based on a gyro-magnetic nonlinear transmission line (GNLTL) to produce a high-voltage pulse with a sub-nanosecond rise time and a relatively high repetition rate, which shows great potential for application in the high-power ultrawideband electromagnetic effect, etc. The influence of incident pulse parameters (rise time and voltage amplitude) and line length on the sharpening characteristics of the GNLTL were investigated experimentally to optimize the rising rate of the modulated pulse front. Based on the GNLTL equivalent circuit model consisting of an LC ladder network, the rise time, the voltage conversion coefficient and the rising rate properties of a modulated pulse were also numerically analyzed in a wider range. The results show that a > 90 kV RF pulse with a rise time of 350 ps and a repetition rate of 1 kHz in burst mode is produced by the GNLTL at an axial biasing magnetic field of 22 kA m−1 and a line length of 30 cm under the condition of a 70 kV incident pulse. Applying a faster and higher incident pulse is conducive to improving the sharpening effect of the GNLTL. Furthermore, within a certain range, increasing the line length of the GNLTL not only reduces the rise time, but increases the voltage conversion coefficient and the rising rate of a modulated pulse. Furthermore, considering the energy loss of ferrite rings, there is an optimal line length to obtain the fastest rising rate of a modulated pulse front edge.

Electrical characteristics of n-ladder network with internal load

The electrical characteristics (including node voltage, branch current, equivalent resistance) of a complex n-ladder network are studied by establishing recursive model with voltage parameters. On this network, not only a load is embedded on any node, but also an arbitrary right boundary resistance is contained. In this paper, the difference equation model of voltage is first established by network analysis, and then the boundary condition equation model is established according to the constraints. The general solution and solution of the difference equation are derived, and then the voltage formula of any node, branch current and equivalent resistance are obtained. The formula obtained in this paper is multifunctional and universal, and the results of many special cases are contained. The equivalent complex impedance of LC ladder network is further studied, and its irregular oscillation and resonance characteristics are revealed.

New oscillator concept based on band edge degeneracy in lumped double‐ladder circuits

An oscillator scheme based on the degenerate band edge (DBE) in a periodic, double-ladder resonant circuit made of lumped elements is proposed for the first time. The circuit exhibits a DBE in the dispersion diagram of its phase-frequency eigenstates and possesses unique resonance features associated with a high loaded Q-factor resonance, compared to a single-ladder circuit. This oscillator is shown to have an oscillation threshold that is half that of a single LC ladder circuit having the same total quality factor, and thus is more robust than an LC oscillator in the presence of losses. Moreover, the double-ladder oscillators have a unique mode selection scheme that leads to stable single-frequency oscillations even when the load is varied. It is also shown that the output amplitude of the double-ladder oscillator is much less sensitive to the output loading compared to single-ladder oscillators. The authors show the analysis and design of such oscillators that potentially lead to enhancing the efficiency of RF components and sources.

Analytical Expression for Resonances of an Inhomogeneous, Radial, Lossless LC Network

This paper is a sequel to the authors’ previous work wherein an analytical expression was derived for the harmonic sum of squares of natural frequencies of a lossless LC ladder network, which is a widely accepted means to model a single, isolated winding for analyzing impulse behavior. The present paper extends the previous result, so that it is applicable to multiple windings in actual transformers. The complexities of the previous work, viz., inhomogeneity and an exhaustive consideration of inductive coupling are retained, and additionally all possible capacitive couplings are now considered. Furthermore, the topology considered in this paper is generic enough to accommodate inductive branches emerging from any node. To the best of authors’ knowledge, there exists no compact closed-form expression to relate the natural frequencies to the inductances and capacitances for a network having this extent of arbitrariness in topology. The success of this method can be ascribed to careful inspection of the inductance matrix to identify hidden pattern and/or structure, followed by their deft manipulation guided by the basic law of mutual coupling between inductors. Interestingly, even a physical meaning can be assigned to each term of the derived expression, and this is done with the intention of assisting its use to conjure new applications.