Showing papers on "RLC circuit published in 1990"

Asymptotic waveform evaluation for timing analysis

Abstract: Asymptotic waveform evaluation (AWE) provides a generalized approach to linear RLC circuit response approximations. The RLC interconnect model may contain floating capacitors, grounded resistors, inductors, and even linear controlled sources. The transient portion of the response is approximated by matching the initial boundary conditions and the first 2q-1 moments of the exact response to a lower-order q-pole model. For the case of an RC tree model, a first-order AWE approximation reduces to the RC tree methods. >

Zero-voltage switching technique in DC/DC converters

Abstract: A novel resonant switch operating under the principle of zero-voltage switching is presented. The basic configurations of the voltage-mode resonant switches are presented. The circuit's operating principles are described using a voltage-mode quasi-resonant boost converter. DC analysis of the converter is carried out. A new family of voltage-mode quasi-resonant converters are derived, and several members of this family are presented. The duality relationship between the zero-current switching technique and the zero-voltage switching technique is derived. These two techniques are compared using an example showing the duality between a current-mode quasi-resonant Buck converter and a voltage-mode quasi-resonant boost converter. The similarities and differences of the voltage-mode quasi-resonant converters and the Class-E converters are discussed. A 5 MHz 50 V to 5 V flyback converter employing the zero-voltage switching technique has been implemented. Design considerations and experimental results of this circuit are presented. >

Analysis of high-speed VLSI interconnects using the asymptotic waveform evaluation technique

Abstract: The asymptotic waveform evaluation (AWE) technique provides a generalized approach to lumped RLC circuit response approximations. Two results are described: (1) generalization of the AWE method to handle interconnect models which contain distributed elements; and (2) application of the generalized AWE technique to the case where the distributed elements can be modeled as lossy coupled transmission lines. The generalized AWE technique is useful for delay and crosstalk estimation and can be used to evaluate transient responses of high-speed interconnect circuits with negligible error compared with conventional circuit simulators, while being two to three orders of magnitude faster. >

Circuit for dimming gas discharge lamps without introducing striations

Abstract: A dimming circuit provides power from an ac source to a compact fluorescent lamp. The circuit generally includes a resonant circuit driven by a high-frequency switching inverter. The resonant circuit is essentially an ac current source and provides sinusoidal current to the lamp, which loads the resonant circuit in parallel. A small amount of dc current is simutaneously provided to the lamp. The resultant asymmetric current waveform flowing through the lamp substantially eliminates striation over a dimming range from about 100% to 1% of full light output.

Analysis and design of class-E/sup 2/ DC/DC converter

Abstract: A family of class-E/sup 2/ DC/DC power converters is introduced. Their analysis and design are presented and experimentally verified. The converters are composed of class-E inverters and class-E rectifiers. Zero-voltage switching (with low dv/dt) of the transistor and zero-current switching (with low di/dt) of the rectifier diode reduce switching losses in both stages of the converters, making them especially suitable for high-frequency operation. Because of the high loaded quality factor of the resonant circuit, the range of frequency required for output-voltage regulation is as narrow as 5.46% for load resistances from a full load of 100 Omega to an open circuit. The full-load overall efficiency is 80.36% at 1 MHz. The converters can also operate at a fixed frequency if synchronous rectifiers are applied. The reduction of class-E/sup 2/ converters to lower order converters is presented. Many multiresonant converter topologies are created in this way. The class-E/sup 2/ converters can be utilized to build highly efficient high-power-density switching power supplies. >

Wide dynamic range direct accelerometer

Abstract: The acceleration input-digital-output sigma-delta modulator accelerometer and the finite-element analysis of the mechanical structure are described. The performance obtained from prototype units is also presented. Silicon micromachining techniques were used to fabricate a high-precision, micro-gee accelerometer. Operating in a closed-loop configuration, the accelerometer utilizes electrostatic field sensing and electrostatic force feedback. The sensor assembly consists of three silicon chips, bonded together at the wafer level. The micromachined sensor is operated in a vacuum to eliminate nonlinear viscous damping and to provide a high-Q second-order mechanical resonant circuit. Near-critical damping is provided by the closed-loop control system. The control system is a highly oversampled sigma-delta modulator that produces a wide dynamic range and a direct digital output. These accelerometers can be built to serve widely diverse markets at a reasonable cost. Frequency ranges from DC to thousands of hertz, accelerations from nano-gees to hundreds of gees, and dynamic ranges in excess of 120 dB can all be accommodated in small rugged silicon accelerometers. >

Activatable/deactivatable security tag for use with an electronic security system

Abstract: A security tag is disclosed for use with an electronic security system for a controlled area. The tag comprises circuitry for initially establishing a resonant circuit having a first resonating frequency within a first frequency range which is outside of the range of the detection frequency of the electronic security system. The tag is activated by changing the resonating frequency of the resonant circuit to a second frequency within the detection frequency range by exposing the resonant circuit to electromagnetic energy within the first frequency range at the predetermined minimum power level to short-circuit a first circuit component. The tag is deactivated by again changing the resonant frequency of the resonant circuit to a third resonant frequency within a third frequency range which is also outside of the detection frequency range by exposing the resonant circuit to electromagnetic energy within the detection frequency range of at least a predetermined minimum power level to short-circuit a second circuit component.

Circuit and method for improved dimming of gas discharge lamps

Abstract: A dimming circuit provides power from an ac source to a compact fluorescent lamp. The circuit generally includes a resonant circuit driven by a high-frequency switching inverter and a current feedback control system. The circuit is essentially an ac current source of unusually high impedance and provides substantially symmetrical high-frequency current to the lamp. This allows flicker-free dimming of compact fluorescent lamps over a wide range with good light output stability. A small amount of dc or low-frequency ac current may be simultaneously provided to the lamp. The resulting composite current waveform flowing through the lamp substantially eliminates visible striations over a dimming range from about 100% to 1% of full light output.

Apparatus for medical instrument placement verification

Abstract: An apparatus for verifying the proper placement of a medical instrument, such as a needle, with respect to an implantable medical device, such as a drug dispensing port or pump. The apparatus includes an internal circuit which is implantable within the body tissue, and an external circuit for communicating with the internal circuit. The internal circuit includes an electrically conductive plate for sensing proper contact between the medical instrument and the medical device. A resonant circuit is coupled between the plate and the body tissue, and has a predetermined resonance frequency, such that an electrical path is established through the resonant circuit, the plate, the body tissue and the medical instrument when the medical instrument is in proper contact with the medical device. The external circuit includes a transmitter circuit for sending signals either pulsed or continuous to the resonant circuit. The transmitted signals have a frequency equal to the resonance frequency, for causing the resonance circuit to resonate when the medical instrument is not properly placed with the respect to the implantable medical device. A receiver circuit detects the resonance signals generated by the resonant circuit, and an alarm circuit responds to the receiver circuit for generating an appropriate alarm signal.

Method for driving an ultrasonic transducer

Abstract: An electronic control system for determining the resonant frequency of and driving ultrasonic transducers in a phacoemulsification probe used for ophthalmic surgery. The control system includes a voltage control led oscillator, power amplifier, power monitor, and automatic gain control circuit operating under the direction of command signals received from a microprocessor-based control console. The control system operates in a constant apparent power, direct drive mode with closed loop feedback maintaining the electrical power provided to the primary of a RLC transformer at the constant level requested by the command signals from the console. The frequency of the drive signal is held at the dominant resonant frequency of the ultrasonic transducer which is being driven by the control system. This resonant frequency is determined via a calibration procedure performed when the probe is first attached to the control system. During this procedure a constant voltage drive signal is swept through a range of frequencies and the electrical power consumed by the transducer is measured and stored at selected intervals such as 100 Hertz increments. The resonant frequency is also determined in part by looking for the frequency at which maximum power is consumed by the probe. The stored data is also subjected to other tests to cheok that the peak is indeed a resonant frequency and that the probe has selected output power characteristics about this resonant frequency thus helping to ensure that the probe is capable of operating satisfactorily when driven by the control system.

An induction motor drive using an improved high frequency resonant DC link inverter

Abstract: An induction motor drive using an improved high-frequency resonant DC link inverter is presented. The resonant circuit was systematically analyzed first to establish the criteria for initial current selection, and a new circuit was then proposed to establish the bidirectional initial current. The proposed current initialization scheme solves voltage overshoot and zero-crossing failure problems in the ordinary resonant DC link inverters. A three-phase 3 kW IGBT (insulated-gate bipolar transistor) based 60 kHz resonant link inverter has been constructed and successfully tested with an induction motor drive. The speed control system is implemented using two microprocessors: TMS320C25 for computation and INTEL 80386 for monitoring and user interface. Experimental results showing the superior operation of the proposed resonant DC link inverter drive are presented. >

Internal combustion engine ignition device

Abstract: The device comprises an a.c. voltage source (5, 6, 7), a resonant circuit (Lf, Cs) coupled to a transformer (9) and a plug (10) which is supplied under high tension by the resonant circuit. An oscillator (11) controls the frequency of the voltage source. Means (14) are provided for detecting the resonant frequency of the circuit (Lf, Cs) and for tuning the oscillator to this frequency during priming. The device further comprises means (13) for adjusting the frequency of the oscillator, after the priming, to a value ensuring the sustaining of the arc and means (15) for cutting this arc after the elapse of a predetermined period.

Rf connector for connecting a mobile radiotelephone to a rack

Abstract: An RF connector for connecting a radiotelephone (1) to an external antenna, whereby the telephone and a corresponding device rack (2) are connected to the external antenna by two pairs of matching metal plates (1a, 2a, 1b, 2b) that provide a capacitive two-wire connector-interface. In order to avoid too large a size and too high an attenuation, a coil (3a, 3b) is connected in series with the pair of plates (1a, 2a; 1b, 2b) constituting each capacitor. The coil and capacitor are dimensioned so that they form a resonant circuit with an attenuation of nearly 0 at the desired transmission frequency. A first balancing transformer (4) before the resonant circuit transforms the signal into a balanced signal, and a second balancing transformer (5) after the resonant circuit transforms the signal back to an unbalanced signal to be transmitted further on a coaxial cable.

Capacitance-type material level indicator and method of operation

Abstract: A system and probe for indicating the level of material in a vessel as a function of material capacitance comprising a resonant circuit including a capacitance probe adapted to be disposed in a vessel so as to be responsive to variations in capacitance as a function of material level. An rf oscillator has an output coupled to the resonant circuit and to a phase detector for detecting variations in phase angle as a function of probe capacitance. Level detection circuitry is responsive to an output of the phase detector and to a reference signal indicative of a predetermined level of material for indicating material level as a function of a difference between capacitance at the probe and the reference signal. In the preferred embodiments of the invention disclosed, an automatic calibration circuit adjusts the resonance characteristics of the parallel resonant circuit of the reference signal indicative of a predetermined reference material level.

Magnetoelastic stress sensor

Abstract: A measuring sensor having a magneto-elastic element and an electronic resonant circuit for sensing mechanical stress of an object. The sensor is firmly attached to the object being measured and creates a resonance frequency. The resonance frequency is transmitted to an aerial in a contactless, position-independent manner.

Fluorescent lamp lighting apparatus

Abstract: A fluorescent lamp lighting apparatus comprising a DC power source (10), a pair of field-effect transistors (32, 34) which are connected in series to each other, in which drains and sources of these transistors are connected in series to each other, whereas gates are connected to an oscillator (36), a pair of voltage-­dividing capacitors (38, 40) which are connected in parallel to the DC power source (10), and an inverter circuit (30) having an insulative leakage transformer (42) whose primary coil (42₁) is connected to a contact between these field-effect transistors (32, 34) and also to the other contact between those capacitors (38, 40). One-ends of filaments (46, 48) of a fluorescent lamp (44) are connected to both ends of the secondary coil (42₂) of the leakage transformer (42), whereas a startup capacitor (50) is connected between the other ends of the filaments (46, 48). By provision of a series resonant circuit composed of the secondary coil (42₂) and the startup capacitor (50), part of the series resonant circuit is released while the fluorescent lamp is off from the lighting apparatus, thus minimizing the resonant output.

CR-type oscillator circuit

Abstract: A CR-type oscillator circuit of the invention includes a reference resistor; a current mirror circuit for taking out the current flowing in the reference resistor; and a reference capacitor whose charging and discharging is repeated by the current taken out by the current mirror circuit within a predetermined potential changing range which is determined by a resistor divider network formed by a plurality of resistors connected in series. The oscillator circuit further includes a control circuit for maintaining at a constant value the ratio between the potential changing range of the charging and discharging of the reference capacitor and the potential difference developed across the reference resistor. The CR-type oscillator circuit of the invention generates stable oscillation frequency which has no dependency on the power supply voltages or the threshold voltages of the transistors concerned.

Field effect transistor amplifier

Abstract: A field effect transistor amplifer has a high gain in a plurality of microwave frequency bands. In a field effect transistor with the gate terminal and the drain terminal thereof connected to a matching circuit on the input side and a matching circuit on the output side, respectively, a resonance circuit which is composed of a series circuit including at least one second inductor and a capacitor and connected in parallel to a resistor, is connected between at least one of the gate terminal of the field effect transistor and the ground and between the drain terminal of the field effect transistor and the ground. When a series circuit including the first inductor, at least one second inductor and the capacitor is resonated and short-circuited, the gain at the resonance frequency is dropped and a gain in the range outside of the desired bands is suppressed. When a series circuit including at least one second inductor and the capacitor and connected to the resistor is resonated and short-circuited, the drop of the gain at the resonance frequency due to the resistor is suppressed. This thereby enables high gains to be obtained in the desired bands.

Circuit arrangement for matching the resonant frequency of an antenna resonant circuit to the output frequency of a transmitter output stage

Abstract: In a circuit arrangement for matching the resonant frequency of an antenna resonant circuit (18) to the output circuit of a transmitter output stage (10), the antenna resonant circuit (18) is coupled via a reactance to the transmitter output stage (10). By means of a current sensor (16), the supply direct current of the transmitter output stage (10) is detected. The value of a tuning component (26), lying in the antenna resonant circuit (18), can be changed by a control signal; the tuning component is a governing factor for the resonance frequency of the antenna resonant circuit (18). A comparator and control unit (36)repeatedly samples the value of the supply direct current detected by the current sensor (16). In dependence upon the result of a comparison with a sequential previously sampled value, it applies th control signal to the tuning component (26) to obtain a maximization of the supply direct current detected.

Damping circuit for the antenna resonance circuit of a radio transmitter-receiver

Abstract: A damping circuit is described for the antenna resonance circuit (28) of a radio transmitter-receiver which in a transmitting phase transmits a time-limited high-energy interrogation pulse and in a receiving phase following the transmitting phase is ready to receive high-frequency re­sponse signals coming from a responder which transmits said response signals as reaction to the reception of the interrogation pulse. In the damping circuit (24) a damp­ing member (R4, R5, R6) is provided which is adapted to be connected to the antenna resonance circuit and disconnected therefrom. A switching means (T4, T5) on receiving a switch­ing voltage applies the damping member (R4, R5, R6) to the antenna resonance circuit (28). A first energy-storage element (C1) chargeable by the HF interrogation pulse serves for furnishing the switching voltage and a second energy-­storage element chargeable by the HF interrogation pulse in dependence upon the time profile of the HF interrogation pulse enables the application of the switching voltage present at the first energy-storage element to the switch­ing means (T4, T5).

Feedback circuit for noiseless damping of the Q of an MRI receiver coil antenna

Abstract: A feedback circuit for a magnetic resonance imaging (MRI) or spectroscopy device comprising a resonant circuit, including an MRI receiver antenna, for generating output voltages in response to nuclear magnetic resonance magnetization signals received by the antenna; an amplifier, coupled to the resonant circuit, for amplifying the output voltages; a resistive feedback path from an output of the amplifier to the resonant circuit, the feedback path carrying a first feedback current; and a capacitive current divider having a tap point to which the first feedback path is connected, for diverting a first portion of the feedback current away from the resonant circuit and for directing a second portion of the first feedback current to the resonant circuit. The Q value of the feedback circuit may be decreased without degrading the signal to noise ratio in order to obtain a sufficient bandwidth for receiving the nuclear magnetic resonance magnetization signals.

Voltage controlled oscillator including a saw resonator

Abstract: A voltage controlled oscillator includes a resonant circuit formed of an impedance in series with a voltage variable capacitance. The impedance consists of a surface acoustic wave resonator in parallel with either an inductance coil or another acoustic wave resonator.

Microcomputer circuit for attenuating oscillations in a resonant circuit by reversing phase and feeding back resonant circuit output oscillation voltage

Abstract: A microcomputer for driving a resonant circuit includes a CPU for processing data, an input circuit for detecting an input signal and for transmitting it to the CPU, an output circuit for outputting an output signal from the CPU to the resonant circuit, and attenuation device for attenuating oscillation in the resonant circuit after the output signal from the CPU is turned off. In a non-contact IC card the resonant circuit is an antenna for sending and receiving data to and from the outside without contact.

Triple-resonance pulse transformer circuit

Abstract: A modified, resonant pulse transformer circuit, based on a generalization of the well‐known double‐resonance pulse transformer circuit, is described. This modified circuit allows complete energy transfer in the presence of non‐negligible internal capacitance of realistic pulse transformers, and substantially reduces peak transformer voltage, compared to the double‐resonance circuit. Conditions under which the internal capacitance significantly affects energy transfer, and sensitivity of overall efficiency to circuit component values are discussed.

Magnetically-coupled, two-resonant-circuit, frequency-division tag

Abstract: A batteryless, portable, frequency divider according to the present invention includes a first resonant LC circuit that is resonant at a first frequency for receiving electromagnetic radiation at the first frequency; and a second resonant LC circuit that is resonant at a second frequency that is one-half the first frequency for transmitting electromagnetic radiation at the second frequency. The first circuit is coupled only magnetically to the second circuit to transfer energy to the second circuit at the first frequency in response to receipt by the first circuit of electromagnetic radiation at the first frequency. The second circuit includes a variable reactance element, such as a variable capacitance diode or varactor, in which the reactance varies with variations in energy transferred from the first circuit for causing the second circuit to transmit electromagnetic radiation at the second frequency in response to the energy transferred from the first circuit at the first frequency. Both resonant circuits include inductance coils that are disposed on a ferrite rod, for enhancing the magnetic coupling. The frequency divider may be extremely small, such as approximately one inch (2.5 cm) in length, but nevertheless has a frequency division energy transfer efficiency of the same order of magnitude as that of much larger frequency dividers. The frequency divider is included in a tag utilized in a presence detection system.

Resonant frequency modulation detector

Abstract: A multilayered radiation detector device (50) including a resonant cavity structure wherein one cavity wall electrode includes a portion of a photovoltaic radiation detector (52). Specifically, a RFM detector has a superconducting transmission line electrode (54) electrically coupled to a high mobility semiconductor layer (58) of the photovoltaic detector. The superconductor transmission line electrode inductance forms, in combinations with a photodetector depletion region capacitance, a series resonant or a parallel resonant circuit. A radiation-induced change in the capacitance results in a change in the circuit resonant frequency and a corresponding variation in the amplitude of an on-resonance RF signal applied to the circuit. In another embodiment the resonant cavity structure includes a gap having a width that is modulated by an amount of absorbed radiation, the radiation-induced change in the distributed cavity capacitance resulting in a change in the cavity resonant frequency.

Two-stage resonant starting circuit for an electrodeless high intensity discharge lamp

Abstract: A starting circuit for an electrodeless HID lamp provides a two-stage resonant starting signal to a gas probe starter of the type comprising a starting chamber which contains a relatively low-pressure gas and is attached to the outer wall of the arc tube. The starting circuit comprises a resonant LC circuit of variable impedance including the series combination of a variable inductance and the parasitic capacitance between the gas probe starter and the excitation coil. In operation, the resonant circuit is tuned to a predetermined value so that, upon application of an RF signal to the excitation coil, resonant operation of the starting circuit results in the application of a sufficiently high starting voltage to the starting chamber to ignite a low-current glow discharge therein. Once the glow discharge is ignited, the starting circuit is retuned to ensure that a sufficiently high starting voltage is capacitively coupled to the arc tube to ionize the arc tube fill and initiate an arc discharge therein.

Inductive coupled object identification system and method

Abstract: An inductive coupled object identification system (FIGS. 2a and 2b) uses inductive coupling to detect and identify objects. Each object includes an object resonance circuit (LT/CT) with a unique object resonance frequency. Base electronics (50) includes an inductive-coupling base coil (L1) coupled to an oscillator circuit (60). To detect an object, the oscillator circuit continually sends START pulses to the base coil. When an object is proximate to the base coil, a START pulse is inductively coupled to the object resonance circuit, causing it to resonate at the object resonance frequency. This resonance condition is detected by the oscillator circuit, which outputs an oscillation signal FREQ at the object resonance frequency. Frequency counting logic (70) is used to determine the object resonance frequency, allowing a microcomputer (80) to identify the object. Two embodiments of the object identification system are described: a dynamic embodiment (FIGS. 1a and 1b) in which ball-shaped objects (10) are dropped into a bowl (13) through a single base coil (L1) in the rim of the bowl, and a static embodiment (FIGS. 1c and 1d) in which ring-shaped objects (20) are placed over a post (23) incorporating multiple base coils (L1-L5). For the static embodiment, the multiple base coils are multiplexed by a base coil selector circuit (FIG. 2b, 100).

Field lighting network with a distributed control system

Abstract: A field lighting network providing for individual control of the light fittings while reducing overall cable costs. A converter unit converts a supply voltage obtained from an A.C. main to a substantially constant current in a Boucherot circuit with a series resonance circuit, tuned to the main frequency. The converter unit includes a Boucherot circuit having a series resonance circuit, substantially tuned on the main frequency, and an additional inductance in series with a load connected to the converter unit. A regulator unit supplied with current couples to each fitting or group of fittings for individual regulation of the current passing through the respective lamp or lamps. Each regulator unit is disposed to receive control information on the power cable.