Showing papers on "RLC circuit published in 1994"

Electrostatically driven vacuum-encapsulated polysilicon resonators part II. theory and performance

Abstract: In this paper, the design, modelling and performance characteristics of electrostatically driven vacuum-encapsulated polysilicon resonators are addressed. A one-port configuration is preferably employed for excitation and detection of the vibration. Mechanical instability (pull-in) is discussed on the basis of the energy minimum principle. An expression for the pull-in voltage of a beam is given. The electromechanical behaviour in a limited frequency regime around the fundamental resonance is accurately modelled by an electric circuit consisting of a (static) capacitor shunted by a series (dynamic) RLC branch. The d.c. bias dependence of the circuit components and of the series resonance frequency has been experimentally investigated and is compared with the theory. The large-amplitude behaviour is discussed as well. The plate modulus and residual strain of boron-doped polysilicon are estimated from the resonance frequencies of microbridges of varying lengths. The feasibility of their application as resonant strain gauges is investigated. The 210 m long beams typically have an unloaded fundamental frequency of 324 kHz, a gauge factor of 2400 and an uncompensated temperature coefficient of -135 ppm 0C-1.

Resonant converter topologies with three and four energy storage elements

Abstract: Generalized half-bridge and full-bridge resonant converter topologies with two, three and four energy storage elements are presented. All possible circuit topologies for such converters under voltage/current driven and voltage/current sinks are discussed. Many of these topologies have not been investigated in open literature. Based on their circuit element connections and source and load excitation types, these topologies are classified into resonant and nonresonant topologies and on their physical realizability. Comparison based on exact steady state analysis are given for typical second- and third-order series resonant converters whereas the fourth-order topology is based on the approximate analysis. >

RICE: rapid interconnect circuit evaluation using AWE

Abstract: This paper describes the Rapid Interconnect Circuit Evaluator (RICE) software developed specifically to analyze RC and RLC interconnect circuit models of virtually any size and complexity RICE focuses specifically on the passive interconnect problem by applying the moment-matching technique of Asymptotic Waveform Evaluation (AWE) and application-specific circuit analysis techniques to yield large gains in run-time efficiency over circuit simulation without sacrificing accuracy Moreover, this focus of AWE on passive interconnect problems permits the use of moment-matching techniques that produce stable, pre-characterized, reduced-order models for RC and RLC interconnects RICE is demonstrated to be as accurate as a transient circuit simulation with hundreds or thousands of times the efficiency The use of RICE is demonstrated on several VLSI interconnect and off-chip microstrip models >

Circuit frequency following technique transponder resonant

Abstract: A transponder system (10) includes an interrogation unit (12) that transmits a first frequency F1 representing a binary zero, and a second frequency F2, representing a binary one. These signals are transmitted from an interrogator resonant circuit (22) within a radio frequency module (16). The transponder system (10) also includes a transponder unit (14) that receives a transmit frequency signal (51) from the interrogation unit (12) at a transponder resonant circuit (42). The transponder resonant circuit (42) is tuned to the first frequency F1 and the second frequency F2. A transponder control module (44) detects a change in the transmit frequency signal (51) from the interrogation unit (12) by a decrease in the voltage amplitude with the transponder resonant circuit (42). The transponder control module (44) repositions a switch circuit (48) that connects and disconnects capacitors within the transponder resonant circuit (42) to match the frequency of the transponder resonant circuit (42) with the new transmit frequency signal (51).

Stray capacitances of two winding transformers: equivalent circuit, measurements, calculation and lowering

Abstract: As long as it works linearly, a two winding transformer is, from an electrostatic point of view, a three port system. Its capacitance matrix includes six independent values. Consequently, whatever its shape, introducing six capacitances in the right places of the equivalent circuit allows the user to account for the whole electrostatic behaviour of this component. With such an equivalent circuit, resonance frequencies can be computed and, reversely, the six capacitances are all deducible from measured resonance frequencies. Thus, using this circuit by hand or by software, interwinding currents of real electronic circuits can be forecasted together with parasitic resonances related to the transformer. After this global approach, a microscopic approach is adopted. A closer look at the winding layer shape and then, at the wire shape itself leads to two simple models which allow the six capacitances of the equivalent circuit to be computed by hand. Values found are approximate but, thanks to analytical expressions, two design rules leading to lower capacitance values are inferred. Measurements are presented to establish the reliability of the equivalent circuit and to evaluate the interest of the proposed designing rules. >

Symmetry control circuit and method

Abstract: The present invention provides a method and circuit for controlling the flow of current through a load. In a preferred embodiment, an oscillator generates a pulse signal of constant frequency. A pulse width modulator adjusts the duty cycle of the pulse signal in response to a dimming level signal input indicative of the desired level of current flow through the load. A converter receives the pulse signal as an input and converts it into an AC signal, the frequency of which follows the frequency of the pulse signal and the symmetry of which varies with the duty cycle of the pulse signal. The load is connected into a resonant circuit tuned such that a change in the symmetry of the AC signal changes the level of current flowing through the load.

Position detecting device and position pointing device therefor

Abstract: A position pointing pen to be used with a position detecting tablet having multiple sequentially activated coils includes a resonance circuit. In response to the resonance circuit receiving from the tablet a wave having greater than a predetermined amplitude, a sequence of twelve different time slots is established during which loading of the resonance circuit is controlled. During eight of the time slots, the resonance circuit is loaded with pen coordinate information obtained from the tablet coils. During a synchronizing time slot the resonance circuit is loaded by a fixed resistor. During the other three time slots the resonance circuit is loaded with other information, e.g. pen pressure, pen up/down, and color. When a coil of the tablet receives two substantially identical wave sequences from the pen the synchronizing containing slot is extracted and a CPU determines pen position and the other information.

Method and apparatus with adaptive transponder plucking

Abstract: A method and apparatus with adaptive transponder plucking is provided in which oscillations from a resonant circuit (12 and 14) are maintained by coupling power from a capacitor (18) through a switch (26) to the resonant circuit (12 and 14). The switch (26) is controlled by adaptive pluck circuitry. The adaptive pluck circuitry includes peak level detector (22) and comparator (24). When the peak level of an oscillating signal from the resonant circuit (12 and 14) falls below a reference voltage, the switch (26) is activated to couple power to the resonant circuit (12 and 14).

Integrated air coil and capacitor and method of making the same

Abstract: In one aspect, the present invention provides an integrated inductor and capacitor 20 which can be used as the inductive portion of a resonant circuit and the energy accumulator for a identification system transponder. In a first embodiment, the integrated inductor and capacitor component 20 may include first and second strips of electrically conductive material 22 and 26, for example aluminum. The first and second strips 22 and 26 are wound in a coil 20 to form a plurality of windings. Each winding is electrically insulated from adjacent ones of the windings by insulators 24 and 28. The component can be bonded to a transponder chip.

High frequency compensated current-mode ladder filters using multiple output OTAs

Abstract: A methodology to implement compensated current-mode filters using multiple output OTAs and based on RLC ladder filter prototypes is presented. The resulting structures are very compact and share the low sensitivity characteristics of the passive RLC prototypes. They can be realized as CMOS circuits since they use only grounded capacitors and OTAs with one of the input terminals grounded. Compensation techniques to minimize degradation in the filter response due to excess phase of OTA parasitic poles are discussed. Simulations with CMOS OTAs and experimental results from discrete circuit implementations using bipolar OTAs are presented that verify the proposed approach. >

Unbalanced FET mixer

Abstract: A unbalanced mixer capable of operation in the absence of DC bias is disclosed herein. The mixer includes an input or local oscillator (LO) port for receiving an input signal. A first transistor has a control terminal coupled to the mixer input port, and an output terminal coupled to a first signal port of the mixer. The mixer further includes a resonator circuit, connected between the transistor control and output terminals, for providing signal isolation between the mixer input port and the first signal port. In a preferred implementation the resonator circuit comprises an inductive element in parallel with a first intrinsic capacitance of the transistor. The mixer may also include a diplexer circuit for coupling signal energy of a first frequency between the output terminal and the first signal port, and for coupling signal energy of a second frequency between the output terminal and a second signal port. A series resonant circuit, connected between the input or LO port and the transistor control terminal, may also be provided for amplifying the input signal. In a preferred implementation the series resonant circuit comprises an input inductive element and an input intrinsic capacitance of the first transistor.

Chemical sensor using eddy current or resonant electromagnetic circuit detection

Abstract: An instrument is applied to the measurement of chemical species and concentration through the use of a chemically-sensitive coating on the eddy current coil or in the vicinity of the eddy current coil which produces a change in impedance of the probe through induced eddy currents in the coating. An eddy current or resonance circuit chemical detector is a non-contact sensor for measuring chemical species identity and concentration. The chemical detector is resilient and does not require reference electrodes. The chemical sensor is selective as a result of data available on the change in vector impedance of the probe, the change in resonant frequency of the tuned circuit, and the availability of data to construct a vector response from multiple probes having differing chemistries. The probe is used in extreme temperatures.

Inverter circuit for use with discharge tube

Abstract: An inverter circuit for use with a discharge tube or lamp such as a cold-cathode fluorescent lamp, a hot-cathode fluorescent lamp, a mercury arc lamp, a metal halide lamp, a neon lamp or the like is provided. The secondary side circuit of a step-up transformer used in the inverter circuit is constructed as a high frequency power supply circuit and a parasitic or stray capacitance produced in the secondary side circuit of the step-up transformer is utilized as a portion or component of a resonance circuit consisting of an inductive ballast or the inductive output of a leakage flux type step-up transformer and the parasitic capacitance.

A Long Pulse Modulator For Reduced Size And Cost

Abstract: A novel modulator has been designed, built and tested for the TESLA test facility. This e{sup +} e{sup {minus}} accelerator concept uses superconducting RF cavities and requires 2ms of RF power at 10 pps. As the final accelerator will require several hundred modulators, a cost effective, space saving and high efficiency design is desired. This modulator used a modest size switched capacitor bank that droops approximately 20% during the pulse. This large droop is compensated for by the use of a resonant LC circuit. The capacitor bank is connected to the high side of a pulse transformer primary using a series GTO switch. The resonant circuit is connected to the low side of the pulse transformer primary. The output pulse is flat to within 1% for 1.9 ms during a 2.3 ms base pulse width. Measured efficiency, from breaker to klystron and including energy lost in the rise time, is approximately 85%.

Multiple frequency tag

Abstract: A multiple frequency tag (118, 218) in one embodiment comprises a generally flat dielectric substrate (220) having first and second generally opposite principal surfaces. A first resonant circuit including a first inductor coil (222) is located on the first surface of the substrate, the first resonant circuit having a first predetermined resonant frequency. A second resonant circuit including a second inductor coil (232) is located on the second surface of the substrate. The second resonant circuit has a second predetermined resonant frequency which preferably is different from the first predetermined resonant frequency. The first inductor coil is positioned on the substrate to partially overlie the second inductor coil in a manner which minimizes the magnetic coupling between the first and second coils. The tag may be employed in an electronic article security system (10) for protecting articles or may be employed in any other type of system for detecting the presence of a tag.

Filter having an electromagnetically tunable transmission zero

Abstract: A transmission line filter comprises four resonators (100, 200, 300, 400), and transmission zeroes can be added to the transfer function of the filter using a known phasing coupling technique using a transmission line (53, 54) coupled between two resonators. The location of the transmission zeroes can be varied using control circuits (A,B). Each control circuit comprises a series coupled inductance (55, 58) and capacitance (56, 59) forming a resonance circuit, the resonance frequency of which can be varied using a variable d.c. voltage (V1, V2). The inductance of each control circuit is arranged adjacent its respective transmission line so that the two are weakly electromagnetically coupled. By supplying the variable voltage to the resonance circuits, normal operation of the phasing coupling is affected, thereby varying the location of the transmission zero. One or more control circuits can be provided for filters having transmission zeroes in their transfer function which need to be varied. The provision of these control circuits allow transmission zeroes to be selected in situ, rather than solely during manufacture.

Self-tuning receiver/decoder for frequency shift keying RF data transmission

Abstract: A self-tuning receiver/decoder for reception of FSK data transmission An RF stage with resonant circuit (10) is tuned to a first of four possible transmitted frequencies for reception of such frequencies according to interrogation at such frequencies in sequence Threshold (18) and counter circuits (12, 16) detect each frequency shift change of transmitted frequency and accordingly retune the resonant circuit to a subsequent unknown frequency by counting through a predetermined sequence for possible reception of each of such frequencies Provision (24) is made for latching frequency shift data bit signals accordingly as output in a format identical to the frequency shift-keying RF format received The receiver/decoder is especially useful for miniaturized transponder operation in which it alternates between receiving and transmitting modes, and is powered by capacitively stored charge in response to continuous transmission of the first frequency over a period

High frequency power distribution system

Abstract: Novel high frequency power distribution systems are disclosed. The system of the present invention uses a relatively high frequency AC (e.g. 100 kHz or higher) and distributes it by a high frequency bus which includes magnetic coupling. AC/DC converters are magnetically connected to the bus by way of associated magnetic coupling and rectify the AC to obtain DC power to be used by a respective load. The bus includes an inductive element which, in one embodiment, forms a series resonant circuit with a capacitive element of the AC/DC converter when it is magnetically connected to the bus.

Zero-voltage switching type electronic ballast for fluorescent lamp

Abstract: A zero-voltage switching type electronic ballast for a fluorescent lamp includes a pair of capacitors connected in series between first and second nodes of a DC power source; a pair of switching devices whose current passages are connected in series between the first and second nodes of the DC power source; a load resonant circuit portion having a serial resonant circuit between the connection node of the pair of capacitors and the connection node of the pair of switching devices, and a discharge lamp; capacitors each connected in parallel to the current passage of the switching devices; a driving transformer having a secondary side which includes first and second windings each connected to the respective switching devices and having opposite polarities, and a third winding having the same polarity as the first winding and connected between the connection node of the pair of switching devices and the load resonant circuit, and a primary side having a fourth winding to which a switching control signal of a predetermined high frequency is applied. A switching control signal generating circuit compares a comparison signal of a predetermined high frequency with first and second reference.

A new IGBT with a monolithic over-current protection circuit

Abstract: A new IGBT structure with a monolithic overcurrent sensing and protection circuit has been developed. The feature of this device is a novel integration of a sensing and protection circuit which consists of a sensing IGBT, lateral n-MOSFET, polycrystalline silicon diode and resistor with an IGBT structure. The conventional IGBT fabrication process is available to this device with only one more photomask. Comparison of not only a short circuit safe operating area but both a trade-off characteristics between an on-state voltage drop and a turn-off loss and reverse biased safe operating area with a conventional IGBT has been investigated. Since exhibiting a large short circuit safe operating area without deterioration of any other device characteristics, this device can be applied to not only a soft switching application like voltage resonant circuit but a hard switching application like snubberless inductive load circuit.

Design of active RLC integrated filters with application in the GHz range

Abstract: In this paper we discuss a method for making possible the active parallel-mode compensation of on-chip inductor and capacitor losses, and for making both the quality factor and the inductance value electronically tunable The application of this technique in filters is emphasized throughout, and is demonstrated in a 2nd-order bandpass filter The paper provides analytical results, discusses transistor-level circuits and presents experimental results from a linearity test on a breadboard >

Unity-power-factor PWM rectifier with DC ripple compensation

Abstract: This paper presents a new topology of PWM rectifier which can achieve unity-power-factor on the AC supply side and ripple-reduction on the DC output side. The main circuit of this rectifier is accomplished by adding only a pair of switches to a conventional PWM rectifier. And it does not need the large DC capacitor or passive L-C resonant circuit. These additional switches and PWM rectifier are controlled not only to make a unity power factor but also to reduce the ripple current. The effectiveness of this circuit is confirmed by the experiments and analysis. This rectifier is useful for UPS and DC power supply, especially in case that the batteries are connected to the DC line. >

Surface deactivateable tag

Abstract: A security tag used with an electronic security system comprises a dielectric substrate having first and second opposite principal surfaces and a resonant circuit capable of resonating at a frequency within a detection frequency range. The resonant circuit is formed, in part, by a first conductive area on the first substrate surface and a second conductive area on the second substrate surface, the two conductive areas being generally aligned with one another to establish a capacitor with the substrate therebetween forming the capacitor dielectric. A third conductive area is provided on one of the principal substrate surfaces proximate to but not electrically connected to one of the two capacitor plates. The third conductive area is electrically connected to the other capacitor plate. A portion of the third conductive area is spaced from a portion of the one capacitor plate by a predetermined minimum distance whereby upon the application of electromagnetic energy to the tag at a frequency generally corresponding to the resonant frequency of the resonant circuit and at or above a predetermined minimum energy level, an electric arc extends between the spaced portions of the third conductive area and the one capacitor plate creating a persistent conductive bridge which connects the two plates of the capacitor in a short circuit.

Robust controller design for a parallel resonant converter using /spl mu/-synthesis

Abstract: DC-to-DC resonant power converters have been the subject of much attention recently. These power converters have the potential to provide high-performance conversion without some of the problems associated with classical pulse-width modulation (PWM)-based converters, thus allowing for smaller, lighter power supplies. However, in order to achieve this, a suitable control circuit, capable of maintaining the desired output voltage under different operating conditions, is required. In the past, small-signal models obtained around the nominal operating points were used to design controllers that attempted to keep the output voltage constant in the presence of input perturbations. However, these controllers did not take into account either load or components variations, and thus could lead to instability in the face of component or load changes. Moreover, the prediction of the frequency range for stability was done a posteriori, either experimentally or by a trial-and-error approach. In this paper, the authors use /spl mu/-synthesis to design a robust controller for a conventional parallel resonant power converter. In addition to guaranteeing stability for a wide range of load conditions, the proposed controller rejects disturbances at the power converter input while keeping the control input and the settling time within values compatible with a practical implementation. These results are validated by means of detailed nonlinear circuit simulations obtained using PSpice.

Interaction of low- and high-frequency oscillations in a nonlinear RLC circuit

Abstract: The interaction of low- and high-frequency oscillations in an RLC circuit with a nonlinear capacitance is studied from the point of the modern theory of dynamical systems It is found that for a certain range of parameters such an interaction may cause chaotic instability, even under the weakly nonlinear excitation conditions The scenarios and conditions that give rise to chaotic oscillations are investigated both numerically and analytically >

RLC active filters with electronically tunable centre frequency and quality factor

Abstract: The Letter discusses techniques for the electronic tuning of inductors and capacitors, and for the active compensation of their losses and thus the enhancement of their quality factors. Applications to integrated RLC filters using on-chip inductors are considered.

Stable high frequency high-pressure discharge lamp lighting device avoiding acoustic resonance

Abstract: A lighting device for a high-pressure discharge lamp includes an inverter circuit for converting a DC voltage into an AC voltage using a pair of switching elements. The switching elements have a switching frequency for starting the high-pressure discharge lamp that is higher than a resonance frequency of a series resonance circuit connected in parallel with the discharge lamp. However, in a lighted state of the discharge lamp, the switching frequency is lower than the resonance frequency of the resonance circuit and is within a frequency range where acoustic resonance does not occur. The lighted state of the high-pressure discharge lamp is maintained by a voltage across a capacitor in the series resonance circuit.

Apparatus for measuring the level of a liquid in a tank

Abstract: A fuel gauging system for use in determining the level of fuel in a tank. The system incorporates a resonant circuit for measuring the resonant frequency of at least one probe immersed in the fuel located in the tank. From measurements of variations of the frequency of resonance, the level of liquid in the tank is determined, and the fuel quantity is then calculated and displayed.

Multi-range voltage controlled resonant circuit

Abstract: A voltage controlled tunable resonant circuit (100) has at least two resonant frequency ranges and reduced self modulation, and includes a resonant element (120), a variable reactance element (130), and a first voltage variable capacitor (VVC) (150). The variable reactance element (130) is coupled to the resonant element (120). The VVC (150) has two fixed capacitance values corresponding to two fixed capacitance bias voltage ranges, and is coupled to the resonant element (120) and the variable reactance element (130). The first VVC (150) is controlled by a first DC bias voltage (190) selected to be within one of the two fixed capacitance bias voltage ranges to establish one of the two resonant frequency ranges over which the voltage controlled tunable resonant circuit (100) is tuned by variation of the variable reactance element (130).

Apparatus for supplying electrical power to an arc lamp including resonant circuit

Abstract: This generator for supplying high-frequency power to an arc lamp (12), coises: a primary circuit (1) connected up to the terminals (5, 6) of the power-supply mains and incorporating an electromagnetic inductor (L', T) connected to a resonant circuit (7); a secondary circuit (2) comprising, in series, the arc lamp (12) and an electromagnetic sensor (E 1 , E 2 ) making it possible to provide magnetic coupling with the primary circuit (1) at high frequency. The secondary circuit (2) is formed by two electrical circuits (10, 11) mounted in parallel with the terminals of the lamp (12), each of the two circuits incorporating an electromagnetic sensor coupled with the electromagnetic inductor of the primary circuit (1).