Parallel LC Research Articles

Self-oscillating electronic ballast analysis using the relay systems approach

In this paper, the authors analyze the self-oscillating LC parallel resonant inverter for electronic ballast applications from a control system point of view. It is observed that the self-oscillating parallel resonant inverter with lamp loads can be naturally modeled as a relay system with negative hysteresis. Based on this formulation, the self-oscillating frequencies of the circuit are found via the time-domain-based Hamel locus. Also, the predicted self-oscillating frequencies via the describing function approach and the Hamel locus approach are compared with the prototype measurement results. It turns out that the accuracy of the frequency prediction via the Hamel locus approach is high, while the accuracy via the describing function approach is circuit Q-value dependent.

Variable directional coupler with LC resonator

A new directional coupler with a frequency control circuit and parallel LC resonator is presented. An exact analysis for a variable directional coupler is derived. Changing the resonance frequency of the parallel resonator for the proposed directional coupler can provide tunable frequency characteristics and a wide operating frequency range.

Accurate measurement of ground-ring inductance in ball grid array package

A new technique has been developed to measure the ground-ring inductance in a ball grid array (BGA) package. A simple parallel LC circuit is used to model the ground-ring parasitics at frequencies up to 1 GHz. After connecting an SMA connector to the ground ring of the BGA package, a network analyser can be used to measure the reflection coefficient (S11) up to 1 GHz from which the ground-ring inductance can be extracted. It has been found that the ground-ring inductance depends very strongly on the phase of S11. This leads to the advantage of excellent accuracy for the extracted quantities. The experimental ground-ring inductance data for a variety of BGA packages are verified by Ansoft simulation results.

On-chip matched 5.2 GHz differential integrated mixer with RF and LO preamplification, fabricated in 0.35 [micro sign]m CMOS technology

An experimental 5.2 GHz integrated LNA/Gilbert cell-mixer IC has been designed. The IC features RF and LO amplifiers, on-chip matching to 50 Ω, differential operation, internal AC coupling of stages, and LC parallel resonant loads at RF, LO, and IF. The return loss is better than –15 dB. Open drain output buffers are used. The IC has NF = 8 dB, and dissipates 105 mW in the core (VSS = –3.3 V), and 16.5 mW in the output buffers.

On-chip matched 5.2 and 5.8 GHz differential LNAs fabricated using 0.35 [micro sign]m CMOS technology

The authors have designed experimental 5.2 and 5.8 GHz low-noise amplifiers (LNAs) using 0.35 /spl mu/m CMOS technology. The ICs feature on-chip matching to 50 /spl Omega/, differential operation, and open drain output buffers. A return loss of better than -15 dB was achieved for both amplifiers. LC parallel resonant loads were used to form the gain peak. The LNAs had a measured noise figure of 4 to 5 dB, at VSS=3.3 V.

A high-frequency electronic ballast for HID lamps based on a /spl lambda//4-long distributed constant line

A novel type of solid-state ballast, which operates in the megahertz-range frequency, is presented in this paper. A circuit composed of a voltage-source half-bridge inverter, a distributed constant line and a parallel LC resonant circuit has been developed for this purpose. The high-intensity discharge (HID) lamp is connected to the output terminal of the inverter through the distributed constant line. Here, since the length of the line is adjusted to 1/4 of the propagation wavelength /spl lambda/ (/spl lambda//4 condition), the output voltage of the voltage-source inverter can be converted to a current source on the load side. Therefore, the ballast can supply not only high voltage to the HID lamp for initiating discharge, but also stable current to it during discharge condition. The modification of the proposed circuit is also proposed in order to expand the operating frequency without increasing the undesirable harmonic current. The experimental results from a prototype system verify the theoretical procedure.

High-power-factor electronic ballast with constant DC-link voltage

This paper presents a high-power-factor (HPF) electronic ballast based on a single power processing stage with constant DC-link voltage. The switching frequency is controlled to maintain the DC-link voltage and the voltage across the switches constant, independently of changes in the AC-input voltage. This control method assures zero-voltage switching (ZVS) for the specified AC-input-voltage range. Besides, with an appropriate design of the fluorescent lamps' drive circuit, the lamps' power can be kept close to the rated value. The power-factor-correction (PFC) stage is formed by a boost power converter operating in the discontinuous conduction mode, which naturally provides HPF to the utility line. The fluorescent lamps are driven by an unmodulated sine-wave current generated from an LC parallel resonant power converter which operates above the resonant frequency to perform ZVS. Theoretical analysis and experimental results are presented for two series-connected 40 W fluorescent lamps operating from 127 V -15% to +10% 60 Hz utility line. The switching frequency is changed from 25 to 45 kHz to maintain the DC-link voltage regulated at 410 V, which leads to a constant output power. The experimental results confirm the high efficiency and HPF of this electronic ballast.

Light-Induced Anchoring Transitions and Bistable Nematic Alignment on Polysiloxane-Based Aligning Surface

We report a novel azimuthal anchoring transition of nematic liquid crystal on a polysiloxane-cinnamate treated surface under the UV irradiation. It is found, that the direction of the light-induced easy axis strongly depends on the irradiation time. Under short exposure times the orienting surface provides an orientation of LC parallel to the direction of the UV light polarization. Longer times give the orthogonal to the UV polarization orientation of LC. There is a region of exposure times that give a bistable anchoring conditions and domains with different directions of the director orientation. We propose a phenomenological model of this anchoring transition and surface bistability based on the competition between trans-cis isomerisation of the side fragments of the polysiloxane-cinnamate material and cross-linking photoreaction of the trans-form of side fragments resulting in orthogonal molecular easy axes.

Modeling of gas-insulated shunt reactor for high-frequency surge analysis

In this paper, we propose a circuit model of gas-insulated shunt reactors for surge analyses in high-frequency regions. The interleaved disk winding, widely used for high-voltage windings, has resonance phenomena in the high-frequency region and its series capacitance decreases above the resonant frequency. In order to simulate this phenomenon, an equivalent circuit composed of three-stage LC parallel circuits was proposed. On the contrary, the continuous disk winding can be simulated by one-stage LC parallel circuit because its series capacitance is almost constant through to the high-frequency region. Impedance characteristics of a full-scale model for a reactor winding were measured and the proposed circuit model was evaluated by comparing the measured results with the calculated ones. It was verified that the proposed model could represent well the winding impedance up to 10 MHz. © 1998 Scripta Technica, Electr Eng Jpn, 123(2): 32–39, 1998

High-frequency Electronic Ballast for HID Lamps Using λ/4-long Distributed Constant Line

A novel solid state ballast, which operates in the MHz-range frequency, is presented in this paper. A circuit composed of a voltage-source half-bridge inverter, a distributed constant line, and a parallel LC resonant circuit has been developed for this purpose. The HID (High Intensity Discharge) lamp is connected to the output terminal of the inverter through the distributed constant line. Here, since the length of the line is adjusted to 1/4 of the propagation wavelength λ(λ/4 condition), the output voltage of the voltage-source inverter can be converted to a current source on the load side. Therefore, the ballast can supply not only high voltage to the HID lamp for initiating discharge but also stable current to it during discharge condition. The modification of the proposed circuit is also presented in order to expand the operating frequency without increasing the undesirable harmonic current. The experimental results from a prototype system verify the theoretical procedure.

High-power-factor electronic ballast operating in critical conduction mode

A high-power factor (HPF) electronic ballast, which exhibits low switching losses, is presented in this paper. The proposed topology is based on a single power-processing stage, which provides high-frequency voltage to fluorescent lamps and HPF to the utility line. The lamps are driven by a self-oscillating LC parallel resonant power converter of great simplicity and attendant low cost and increased reliability. HPF is achieved by using a nonconventional boost power converter operating in critical conduction mode. Theoretical analysis and experimental results for two 40-W fluorescent lamps operating at 50 kHz from a 127-V utility line have been obtained, which demonstrate the high efficiency and HPF of this electronic ballast.

Bistability in the frequency response of a driven SQUID ring-radio frequency resonator system

We discuss the experimental observation of the frequency response of a parallel LC tank circuit inductively coupled to a SQUID ring. We show that when the rms rf flux that couples to the ring is a significant fraction of the superconducting flux quantum, Φ o (= h 2e ) , the resonance exhibits a cyclic fold bistability.

Improving the Power Consumption Characteristics of Piezoelectric Actuators

A study of the application of power factor correction methods to piezoceramic actua tors is performed. The power factor is corrected by adding an inductor both parallel to and in series with the piezoceramic actuator. The actuator consists of two lead zirconate titanate (PZT) patches mounted symmetrically to a cantilever beam. The inductance values were chosen such that each inductor-capacitor (LC) circuit was at resonance at the second natural frequency of the beam. Imple menting the parallel LC circuit reduced the current consumption of the piezoceramic actuator by 75 % when compared to the current consumption of the actuator used without an inductor. Imple menting the series LC circuit produced a 300 % increase in the voltage applied to the actuator com pared to the case when no inductor was used. In both cases, employing power factor correction methods corrected the power factor to near unity and reduced the apparent power by 12 dB. A theo retical model of each circuit was developed, and the analytical and empirical results are virtually identical. The results of this study can be used to synthesize circuits to modify piezoceramic actua tors, reducing the voltage or current requirements of the amplifiers used to drive those actuators.

IDEAL TURBULENCE IN AN IDEALIZED TIME-DELAYED CHUA’S CIRCUIT

By replacing the parallel LC “resonator” in Chua’s circuit by a lossless transmission line, terminated by a short circuit, we obtain a “time-delayed Chua’s circuit” whose time evolution is described by a pair of linear partial differential equations with a nonlinear boundary condition. If we neglect the capacitance across the Chua’s diode, described by a nonsymmetric piecewiselinear vR–iR characteristic, the resulting idealized time-delayed Chua’s circuit is described exactly by a scalar nonlinear difference equation with continuous time, which makes it possible to characterize its associated nonlinear dynamics and spatial chaotic phenomena. From a mathematical viewpoint, circuits described by ordinary differential equations can generate only temporal chaos, while the time-delayed Chua’s circuit can generate spatiotem poral chaos. Except for stepwise periodic oscillations, the typical solutions of the idealized time-delayed Chua’s circuit consist of either weak turbulence, or strong turbulence, which are examples of “ideal” (or “dry”) turbulence. In both cases, we can observe infinite processes of spatiotemporal coherent structure formations. Under weak turbulence, the graphs of the solution tend to limit sets which are fractals with a Hausdorff dimension between 1 and 3, and is therefore larger than the topological dimension (of sets). Under strong turbulence, the “limit” oscillations are oscillations whose amplitudes are random functions. This means that the attractor of the idealized time-delayed Chua’s circuit already contains random functions, and spatial self-stochasticity phenomenon can be observed.

Chaos from a time-delayed Chua's circuit

By replacing the parallel LC resonator in Chua's circuit by a lossless transmission line that is terminated by a short we obtain a Chua's circuit, whose time evolution is described by a pair of linear partial differential equations with a nonlinear boundary condition. If we neglect the capacitance across the Chua's diode, which is described by a nonsymmetric piecewise-linear V/sub R/-I/sub R/ characteristic, the resulting idealized Chua's circuit is described exactly by a scalar nonlinear difference equation with continuous time, which makes it possible to characterize its associated nonlinear dynamics and spatial chaotic phenomena. From a mathematical view point, circuits described by ordinary differential equations can generate only temporal chaos, whereas the time-delayed Chua's circuit can generate spatial temporal chaos. Except for stepwise periodic oscillations, the typical solutions of the idealized time-delayed Chua's circuit consist of either weak turbulence or strong turbulence, which are examples of ideal (or dry) turbulence. In both cases, we can observe infinite processes of spatial-temporal coherent structure formations. Under weak turbulence, the graphs of the solution tend to sets that are fractals with a Hausdorff dimension between 1 and 2 and is therefore larger than the topological dimension (of sets). Under strong turbulence, the limit oscillations are oscillations whose amplitudes are random functions. This means that the attractor of the idealized time-delayed Chua's circuit already contains random functions, and spatial self-stochasticity phenomenon can be observed. >

High-frequency APC combustion-surface resistivity

We measured the frequency dependence of the surface resistance for burning APC at 1-20 MHz with specimens containing combustible film electrodes prepared by the [i] method. Figure 1 shows the block diagram. The specimen 1 containing the tin electrodes 2 was connected to a parallel LC circuit in a Q meter type E4-4 (item 3 in figure). The Q-meter signal passed to the light-beam oscillograph 4 type N-II7. The signal proportional to the quality factor was recorded. The surface resistance is given by

Ac susceptibility apparatus for measuring the transition temperature of high-T c crystals, sintered samples, and films

We describe a simple ac magnetic susceptibility system which can be used to observe the superconducting transition temperature in the range 4.2–300 K. The apparatus is extremely flexible and has been tested using high-quality YBa2Cu3O7−x single crystals with volume as small as 2×10−5 cm3, much larger sintered polycrystalline samples of the same compound, and finally thin films deposited over a surface area of 1 cm2. The system measures resonant frequency variations of a parallel LC circuit with the superconductor close to the inductor. Typical frequencies and fields are in the ranges 0.2–10 MHz and 1–2 mG ac in the inductor.

Magnetooptic direct overwrite using a resonant bias coil

A method is introduced for achieving direct (single-pass) overwrite in magnetooptical disk systems. In this method, a sinusoidal magnetic bias field is efficiently generated by incorporating the bias coil in a parallel resonant LC circuit. Magnetooptic domains of either sign can be written by timing laser pulses to coincide with either positive or negative peaks of the field. Continuous domains of variable length are written by overlapping the domains generated by successive laser pulses. Using a bias field with a fixed frequency of 4.5 MHz, carriers at various lower frequencies were written on a TbFe disk with 47-dB carrier-to-noise ratio. Direct overwrite resulted in erasure of old carriers by at least 34 dB. Suitable run-length-limited coding schemes are discussed, and a novel code type, called (d, k)-even 0, is introduced. >

Analysis of a simple phase shifter

Cosgrove, Neck, and Finch (I) have recently presented an interesting design for a continuously variable phase shifter at 100 MHz based on a quadrature hybrid splitter and varactor tuned circuit. In evaluating the applicability of such a device to lower frequency, it has been necessary to employ a more detailed analysis than was presented. The properties of quadrature hybrid splitters are discussed in many sources including manufacturer’s catalogs (2). They are four-port devices with the property that a signal applied at any port will appear at two others with phase shifts of 0 and -90”. It is convenient to label these ports as IN, 0, -90, and IS0 such that a signal applied at IN will appear at the 0 and -90 ports. If these ports are terminated with the characteristic impedance of the device, Z,, no signal appears at the IS0 port. The phase shifter of Ref. (I) is based on the property that if the 0 and -90 ports are terminated with an impedance 2, such that the voltage reflection coefficient is p = (2 &)/ (Z + a), then the reflected signals sum at the IS0 port but do not appear at the IN port. Inspection of the design of Ref. (1) indicates that use has been made of a parallel LC circuit as the terminating impedance on ports 0 and -90 with other capacitors employed to provide dc isolation and rf ground. A schematic of this arrangement is shown in Fig. 1. The case where there is a finite resistance in series with the inductor is shown in Fig. 1 b. Both cases have been analysed and numerically simulated. In the design of Ref. (I), the inductors end on a common conductor to which the varactor control voltage is applied. This conductor is maintained at rf ground by a fixed capacitor. The situation in which this capacitor is insufficient to isolate the two terminating circuits has also been considered. It is preferable to apply the control voltage at a point of rf ground. The negative side of the varactor diode, however, must be at a high impedance point for the rf and the use of a parallel LC circuit as employed in Ref. (I) appears to be the best scheme for accomplishing this. Accordingly, no other termination schemes have been investigated in this work. For the circuit shown in Fig. 1, application at port IN of a signal VOeiU’ results in the appearance, at port ISO, of a signal p Voeior-*12 where p = (Z &)/(Z + &) is the voltage reflection coefficient for a transmission line of characteristic impedance 2 = IZle’@. Writing p = IpIe”, one finds that the phase shift at the IS0 port is 0 7r/2. Expressing p in terms of 1.~1 and 4, one finds (p( = (PI4 + al 4z12.z$~wdw2 1212+ z; + 2Iz~z,cos(c#l) [II

Auxiliary circuits for pulse bias and equivalent series resistance measurements with a Boonton 72B capacitance meter

Pulse bias and equivalent series resistance circuits have been developed to expand the capabilities of a Boonton 72B capacitance meter used in MOS capacitor characterization. With the help of tuned parallel and series LC circuits, pulses of 5 μs length can be applied directly to the capacitor under test, avoiding the built-in bias circuitry of the capacitance meter. The equivalent series resistance measurement circuit, used in a computer-controlled automated measurement system, makes it possible to determine both the real and imaginary components of an unknown impedance rather than the equivalent parallel capacitance only.