Showing papers on "RLC circuit published in 1984"

Q-Factor Measurement with Network Analyzer

Abstract: Ginzton's impedance method of Q-factor measurement is adapted to network analyzer techniques. The circuit model of the resonator incorporates also an external reactance which varies linearly with frequency to take into account the effects of the coupling mechanism and the influence of the distant resonant modes.

Quantum well oscillators

Abstract: Oscillations have been observed for the first time from double barrier resonant tunneling structures. By eliminating impurities from the wells, we have been able to increase the tunneling current density by a factor of nearly 100. With the attendant increase in gain and improved impedance match to the resonant circuit, the devices oscillated readily in the negative resistance region. Oscillator output power of 5 μW and frequencies up to 18 GHz have been achieved with a dc to rf efficiency of 2.4% at temperatures as high as 200 K. It is shown that higher frequencies and higher powers can be expected.

Switching electrical power supply utilizing miniature inductors integrally in a PCB

Abstract: Electrical switching power supply for microprocessors and the like comprising a high voltage d.c. source (30, 34, 32, 50) resonant circuit (38, 51, 42, 52) including a switching transistor (52) which is operated in Megahertz range and provides pulses, via a transformer (40), rectifier (56), smoothing choke (62) to a d.c. low voltage output terminal (66). The rate of switching is controlled by a pulse generator (54) which pulses variably in response to output voltage to thereby vary switching repetition rate and hold to a predetermined output voltage. The inductive elements use spirals (12A and 12A') of thin lines on the surface of a substrate board and ferrite plugs (20) passing through holes (22) in the board to provide miniature inductive elements built into the substrate for effective use in a microprocessor power supply, or the like, and in other applications. Power dissipating elements on the circuit are mounted to a common thermal ground (29) and the circuit as a whole, including such thermal ground is encapsulated to provide a plate form power supply.

Ultrasonic liquid atomizer with an improved soft start circuit

Abstract: In an ultrasonic liquid atomizer, an oscillator has a transistor and a resonant circuit a part of which is formed by a piezoelectric vibrator mounted in an energy transfer relationship with liquid in a chamber. The transistor and the resonant circuit receive a full-wave rectified supply voltage to generate ultrasonic energy in the vibrator in the presence of a bias voltage. A soft start circuit has a time constant circuit responsive to the bias voltage and a transistor responsive to an output of the time constant circuit which provides switching action in phase with the full-wave rectified supply voltage so that ultrasonic energy is generated in the form of a series of bursts having durations gradually increasing as a function of time during an initial brief interval from application of the bias voltage to the oscillator. A bias stabilizer has a second time constant circuit responsive to the bias voltage and a transistor connected to the output of the second time constant circuit to establish a low impedance path across the base and emitter of the transistor of soft start circuit after termination of the initial brief interval.

Dual band transceiver antenna

Abstract: A dual band antenna (11) for a radio transceiver includes a conductor of a predetermined length with a feedpoint (24) located substantially central of the conductor. Radiator elements (26, 28) terminate the ends of the conductor and ground plane (30) terminates the radiator elements. An impedance matching circuit (32) is coupled to the feed point whereby the high impedance part of the antenna is confined to the center. Dual banding elements (42, 44) coupled to the impedance matching circuit with a high Q resonant circuit element. Input/output circuits (46) are also coupled to the dual banding elements. The design minimizes the effect on the antenna by the proximity of user's hands, head and body.

Distributed capacitance LC resonant circuit

Abstract: An electronic article surveillance system and a marker for use therein, which marker comprises a tuned resonant circuit including inductive and capacitive components formed of a laminate of a dielectric and conductive-multi-turn spirals on opposing surfaces of the dielectric, wherein the capacitive component is formed as a result of distributed capacitance between the opposed spirals, and wherein the circuit thereby resonates at at least two predetermined frequencies which are subsequently received to create an output signal.

Regulated dc to dc converter

Abstract: A DC-DC converter includes first and second switches to be opened and closed at mutually exclusive times at a predetermined frequency. The first switch is connected to an inductor and a transformer primary winding so that a first current component from a DC input supply flows through it via the inductor. A second current component having a sinusoid component flows through the first switch in response to discharge of energy stored in a resonant circuit coupled to the transformer. The second component begins approximately simultaneously with closure of the first switch. The second switch, when closed, is connected so that a bidirectional current component flows through it in response to energy stored in the inductor. The rectifier is connected between the secondary winding and the load so the secondary winding supplies substantial current to the load.

Tuning systems on dielectric substrates

Abstract: A tuning system employs a specific resonant circuit which includes two electrodes confronting each other through a dielectric interposed therebetween. Each of the two electrodes has at least one bent portion to present a lumped-constant inductance and has a desired equivalent electrical length. The two electrodes respectively have common terminals located out of mutually confronting positions so that voltage signals induced by mutual inductance between the electrodes will be opposite in phase so as to thereby produce a parasitic distributed-constant capacitance. The two electrodes form a two-terminal circuit network having a first terminal disposed at a desired position on one of the two electrodes and the common terminals as a second terminal. The first terminal of the resonant circuit is connected to a feedback amplifier, an amplifier, or a mixer so as to form a tuning oscillator, a tuning amplifier or a mixer.

Broad-band guided-wave electrooptic modulators

Abstract: Lumped-element Mach-Zehnder interferometric modulators have been designed, fabricated in LiNbO 3 , tested and analyzed. These modulators had 3 dB bandwidths from 280 MHz to 2.75 GHz and V π 's from 1 V to 4 V, respectively. A simple RLC equivalent circuit is utilized to model the packaged modulator performance and results are compared with those measured using a swept-frequency technique. The model is seen to break down at the higher frequencies due to a frequency-dependent resistance and the electrode and parasitic inductances are seen to limit the overall modulator performance. The effects of varying the electrode capacitance, resistance, or inductance on modulator performance are demonstrated.

Tuning arrangement for interfacing credit card-like device to a reader system

Abstract: A circuit for maximizing power transfer from a station to an interactive memory card via a capacitive interface. A reader system in the station generates an ac signal which provides operating power that is transferred to the card through the capacitive interface formed when the card is placed against a window on the station. The ac signal from the station is directed through a series resonant circuit to the card. The capacitive interface between the station and card make up the capacitive element of the resonance circuit while the series combination of the secondary of a transformer and an electrically variable inductor form the inductive element. Use of the variable inductor allows the station to tune the circuit to resonance and cancel the capacitive element, thereby maintaining maximum power transfer to the card.

Tuning of a resonant circuit in a communications receiver

Abstract: A method and apparatus is provided for the tuning of the resonant circuits of a communications receiver. The frequency f D is generated with an additional oscillator, which frequency is then mixed with the receiver oscillator frequency, of which three frequencies fo, fo+f D , fo-f D are formed and are applied to the antenna output. The frequency f D , which is evaluated as a narrow band, is generated by mixing at the intermediate frequency output. A maximum balancing is provided over all high-frequency circuits. The acceptor circuits are tuned to fo and fo+f D (N+5, N+11) for obtaining maximum damping of the oscillator frequency and of the mirror frequency, where N+5 and N+11 represent mirror frequencies.

A history of network synthesis and filter theory for circuits composed of resistors, inductors, and capacitors

Abstract: This paper is an informal history of the birth and growth of network synthesis and filter theory, as it was developed for RLC circuits. It includes events, experiences, and anecdotes which are not all well documented but may make interesting reading. Other papers in this issue are histories of other aspects of circuit theory; for the most part descended from the RLC theory.

Balanced Feedback Oscillators

Abstract: The oscillator circuit comprises an amplifier having a pair of inputs, a positive feedback path producing a positive feedback ratio to one of the inputs, and a negative feedback path including a series resonant circuit producing a negative feedback ratio to the other of the inputs. The positive and negative feedback paths are independent such that the current in each of the paths can be adjusted independently. In this manner, a high Q multiplier effect is achieved. Also, the circuit has an output path which is separate from the input path so that a high output signal level can be achieved while maintaining a low current through the series resonant circuit.

Detecting device having spaced transmitting and receiving coils for detecting a metal strip embedded in paper money

Abstract: The metal detecting device includes first and second coils provided on both sides of a passageway for paper money. This metal detecting device is designed for use in detecting a metal strip embedded in the paper money in order to determine whether the paper money is genuine or counterfeit. The first coil is connected to a high frequency AC source to generate an AC magnetic field. The second coil is connected to a capacitor to form a resonance circuit which resonates at the same frequency as the AC current. The variation of the Q factor of the resonance circuit due to eddy-current losses produced in the metal strip of the paper money is used by a detecting circuit to determine whether the paper money passing through the space between the first and second coils is genuine.

Electronic article surveillance system using marker containing a distributed capacitance lc resonant circuit

Abstract: An electronic article surveillance system and a marker for use therein, which marker comprises a tuned resonant circuit including inductive and capacitive components formed of a laminate of a dielectric and conductive-multi-turn spirals on opposing surfaces of the dielectric, wherein the capacitive component is formed as a result of distributed capacitance between the opposed spirals, and wherein the circuit thereby resonates at at least two predetermined frequencies which are subsequently received to create an output signal. An electrical connection is desirably provided between predetermined portions of the opposing spirals to lower the resonant frequencies.

Active damping of ultrasonic transducers for robotic applications

Abstract: Ultrasonic ranging in air over short distances offers advantages for robotic applications. Such sensing methods can employ transducers small enough to fit into a robot gripper, thereby providing terminal homing capability. Any such short range time-of-flight systems, however, have to solve the problem of rapid receiver recovery after the transmit pulse. In the present case the problem has been solved by an active damping scheme. The transducer is a capacitive element and is connected across an inductor to form an electrically resonant circuit at the acoustic frequency of interest. The LC tank is in the feedback path of a novel circuit that can be changed continuously from positive to negative feedback conditions. When the feedback is positive oscillations rapidly build up, when negative they just as rapidly die down. At the end of each positive - negative cycle essentially all of both the electrical and mechanical energy has been extracted from the system, which is then ready to receive the echo. In this way ranging is readily achieved down to ∼1", which is adequate for robot gripper applications.

East-west correction circuit

Abstract: In a deflection circuit, a flyback transformer and a retrace resonant circuit that includes a deflection winding are mutually coupled by a relatively small capacitor during the retrace interval so as to reduce transient distortions that may be caused by a sudden high beam current change. East-west modulation is provided to the deflection circuit output stage via an impedance having a relatively large value at the retrace frequency. A resonant circuit that includes the deflection winding and the flyback transformer is tuned to the retrace frequency. Synchronization information of the current through the deflection winding may be derived from a winding of the flyback transformer.

An Iterative Pole-Removal Method for Synthesis of Power System Equivalent Networks

Abstract: In power system simulation (by means of TNA or digital computer) equivalent networks can be used to reduce the simulation complexity. This paper presents an iterative pole-removal method based on the least-squares fitting techniq% to synthesize RLC equivalent networks according7 to their specified driving-point function in the frequency domain. The synthesized networks are composed of only passive components to represent the DC constant, complex poles as well as poles at zero and infinite. Poles are removed individually from the specified driving-point function applying the least-squares fitting with respect to the frequency domain around the relevant resonance. This algorithm converges quickly even for highly resistive systems.

Microwave generation in NERFET

Abstract: Microwave generation in a NEgative Resistance Field-Effect Transistor (NERFET) is reported for the first time. This device is based on a GaAs/AlGaAs heterostructure which exhibits negative differential resistance due to a transfer of hot-electrons out of a source-drain channel and into a conducting substrate. In an untuned microwave circuit at 77 K, the NERFET was found to generate wide-band noise at frequencies up to 2.3 GHz. In a tunable resonant circuit, stable microwave oscillations were observed at frequencies as high as 1.45 GHz. While further experiments are needed to determine the performance limits of the NERFET, the preliminary results presented here demonstrate the potential of this new device as a high-frequency element.

Inverter for feeding discharge lamps

Abstract: 1. An inverter comprising two switches (T1, T2) which can be alternately rendered conductive, and comprising a load circuit arranged parallel to the first switch (T1) and connected via the second switch (T2) to a d. c. voltage source (Q), and consisting of the series arrangement of a reversible oscillatory capacitor (C10), a series resonant circuit composed of a choke (L1) and a capacitor (C9), and a discharge lamp (LP) equipped with heatable electrodes, where these electrodes are arranged in the load circuit and are connected to one another via the capacitor (C9) of the series resonant circuit, and comprising a control set (S) which supplies control voltages which alternately render the switches conductive, characterised by a burning voltage sensor (B) which monitors the burning voltage of the lamp (LP) and supplies an output signal dependent upon the burning voltage and fed to the control set (S) to determine the frequency of the control voltages which it supplies.

Charged particle accelerator using quadrupole electrodes

Abstract: A charged particle accelerator is provided with quadrupole electrodes with surfaces that are opposed to each other and are undulated, and with an external resonance circuit. The external resonance circuit consists of a capacitor formed by the opposing electrodes, a variable capacitor provided in parallel with said capacitor, and a coil. The resonance frequency is variable. A direct current and an alternating current may be applied in a superposed manner to the quadrupole electrodes. The thus constructed accelerator can be employed for an ion implanter to implant a heavy-current ion beam of several hundred KeV to several MeV.

Starting and operating method and apparatus for discharge lamps

Abstract: Starting and operating method and apparatus for discharge lamps comprises a current-limiting and rectifying means which provides at its output a low-ripple current-limited direct current. To effect lamp starting, a series-connected inductor and capacitor form a high "Q" resonant circuit with the capacitor connected across the lamp to be operated. This starting circuit connects through a blocking capacitor and charging resistor across the low-ripple source of DC. A pair of transistors which comprise an oscillator are connected emitter-to-collector across the source of DC, with the common-connected emitter and collector connected to the blocking capacitor. A drive air-core transformer has separate feedback windings in the starting and operating circuits and drive windings are associated with the transistors. A trigger diode is used to initially pulse one of the transistors which initially oscillate to generate square waves having a frequency corresponding to the resonant frequency of the starting circuit. After the lamp strikes, the transistors operate in a self-oscillating mode with the operating frequency determined by the rate of current flow into the operating feedback winding.

Calculation of period doubling in a Josephson circuit

Abstract: The method of harmonic balance is used to obtain analytic results for the differential equation describing a current-biased Josephson junction with self-capacitance that is shunted by a resistor with substantial self-inductance. This system is known to exhibit period-doubling cascades, chaos, and other exotic nonlinear phenomena. After an accurate representation of the basic voltage oscillation is determined for high-bias currents, the value of bias current is computed for which this solution loses stability to a period-doubled mode. The predictions agree to remarkable accuracy with results obtained from both analog simulations and digital integration of the circuit equation, typically 5% for moderate values of inductance. Moreover, the method of calculation provides a systematic scheme for achieving increasing accuracy.

Loudspeaker system with combination crossover and equalizer

Abstract: A crossover network with a parallel resonant circuit in the high frequency branch is utilized to drive two loudspeakers, one in a low frequency range, and the other in the high frequency range. The resonant frequency of the resonant circuit lies in the upper end of the high frequency portion of the loudspeaker response.

Non-contact inductive distance measuring system with temperature compensation

Abstract: A non-contact level measurement system for monitoring distances with very high accuracy between a sensor coil and a metallic object such as a molten liquid level over either very narrow or extended distances. Means are provided for compensating for temperature and other non-linear effects including other inductive fields, environmental changes and the like. The system incorporates an L-C resonant circuit connected between the output of an oscillator and the input of an operational amplifier.

A 69 GHz Monolithic FET Oscillator

Abstract: A monolithic oscillator was fabricated using conventional planar FET technology. The active device used was a 0.35x60 micron FET fabricated on an active layer formed by ion implantation into an undoped VPE buffer layer. Frequency stability is achieved using either an on-chip microstrip resonant circuit or by adding a 30 mil diameter dielectric resonator directly onto the 50 mil square GaAs chip. With no external tuning the oscillator delivered 0.45 milliwatts at 64 GHz. By using an external E-H waveguide tuner, 0.7 milliwatts of power at 65.7 GHz was achieved. The oscillator was tunable from 55 to 75 GHz by adjusting the source-gate tuning inductor and the drain tuning.

Drift-equalized, multi-frequency oscillator

Abstract: An oscillator having the ability to oscillate at a plurality of discrete frequencies in response to an applied digital signal is disclosed. A crystal-controlled, resonant circuit utilizing passive components as frequency determining elements and a PIN diode switching scheme allows the oscillator to demonstrate a tendency for each of the plurality of discrete frequencies to drift equally in response to temperature changes. A two-transistor, emitter coupled amplifying section uses a current mirror for biasing and provides an impedance matching network.

Proximity switch with minimum current consumption

Abstract: To achieve a proximity switch with minimum current consumption and at the same time little circuit and component expenditure, it is provided in accordance with the invention that an electrical resonant circuit (3, 4), the coil (3) of which can be influenced by the proximity, is excited into oscillation by a direct-current pulse, that the degree of proximity is inferred from the decaying process of the damped oscillation thus generated and that the excitation of the resonant circuit is effected periodically by a pulse sequence.

Inverter circuit arrangement

Abstract: An inverter comprises a pair of circuits (suffixed A and B respectively) each comprising a transformer 3 a primary winding 17 of which is connected with alternating polarity across input terminals 1, 2 via a choke 7 by means of a pair of switches 8, 9 (such as FET's Fig. 5) for periods equal to one-half the period of the resonant frequency of the resonant circuit comprising the transformer primary winding 17 and a capacitor 16 connected across it. The resonant frequency is the same for both circuits. To control the voltage across output terminals 4, 5 in spite of the constant-current properties of the chokes the transformers have a common secondary winding 18 and the phase of the antiphase switching signals applied to the switches of one circuit is made variable with respect to the phase of the antiphase switching signals applied to the switches of the other circuit by varying a control signal 13 applied to a switching signal generator 12, thereby varying the relative phases of the signals (V1, V2 Figs. 2a, 2b, 2c) contributing to the voltage (44, 37, 40) across the secondary winding. The transformers may have completely separate magnetic circuits or their magnetic circuits may have a portion in common, on which portion the secondary winding is provided.