428 results about "Lc resonant circuit" patented technology

A voltage controlled LC resonance oscillation circuit has a plurality of capacitive elements connected to an output node. These capacitive elements are applied with voltages at opposing terminals for selecting an oscillating frequency band, so that the oscillating frequency band can be changed step by step in accordance with the selection voltage. The capacitive elements include at least one variable capacitive element such as a MOS capacitor, the capacitance of which is varied in accordance with a voltage applied thereto. The MOS capacitor is similar in structure to a MOS transistor. The variable capacitive element can be supplied at a terminal opposite to the output node with a voltage from a variable voltage source, for example, in place of the selection voltage. The voltage controlled LC resonance oscillation circuit can measure the output amplitude and oscillating frequency without affecting the characteristics thereof, and reduce the parasitic capacitance.

A proximity sensor has an oscillation circuit, an amplitude measurement circuit, a control circuit and a signal processing circuit. The oscillation circuit has an LC resonant circuit and an oscillation control circuit that is configured to supply an electric current to the LC resonant circuit to generate oscillating voltage across the LC resonant circuit. The amplitude measurement circuit is configured to produce an amplitude signal corresponding to the amplitude of the oscillating voltage. The control circuit is configured to set the negative conductance of the oscillation control circuit to a critical value by which the LC resonant circuit can oscillate based on the amplitude signal. The signal processing circuit is configured to produce a distance signal corresponding to the distance between an object and the sensing coil based on a parameter associated with the negative conductance.

An analytical device for rapid, non-invasive nuclear magnetic resonance (NMR) spectroscopy of multiple samples using a single spectrometer is provided. A modified toroid cavity/coil detector (TCD), and methods for conducting the simultaneous acquisition of NMR data for multiple samples including a protocol for testing NMR multi-detectors are provided. One embodiment includes a plurality of LC resonant circuits including spatially separated toroid coil inductors, each toroid coil inductor enveloping its corresponding sample volume, and tuned to resonate at a predefined frequency using a variable capacitor. The toroid coil is formed into a loop, where both ends of the toroid coil are brought into coincidence. Another embodiment includes multiple micro Helmholtz coils arranged on a circular perimeter concentric with a central conductor of the toroid cavity.

A switched-capacitor voltage converter which is particularly well-suited for receiving a line voltage from which to drive current through a series of light emitting diodes (LEDs). Input voltage is rectified in a multi-level rectifier network having switched capacitors in an ascending-bank configuration for passing voltages in uniform steps between zero volts up to full received voltage V_DC. A regulator section, operating on V_DC, comprises switched-capacitor stages of H-bridge switching and flying capacitors. A current controlled oscillator drives the states of the switched-capacitor stages and changes its frequency to maintain a constant current to the load. Embodiments are described for isolating the load from the mains, utilizing an LC tank circuit or a multi-primary-winding transformer.

A stylus without active components includes a housing, and a resonant circuit, such as an LC resonant circuit, disposed in the housing. The resonant circuit is operatively configured to one of a plurality of resonant frequencies respectively associated with a plurality of function modes.

Disclosed is a synchronous rectifier type SRC for operating in an intermittence mode, which includes: an input power for supplying the input DC voltage; an input-side switching unit for switching four input-side switching devices to convert the input DC voltage to AC voltage, the input-side switching unit being connected to the input power, an LC resonance circuit for storing energy in a resonance inductor and a resonance capacitor by means of LC resonance, and outputting resonance voltage, the LC resonance circuit being connected to the input-side switching unit; a transformer with a primary winding and a secondary winding for converting the resonance voltage to voltage of a predetermined level according to a turn ratio to generate secondary voltage, and transferring the secondary voltage through the secondary winding, the primary winding being connected to the LC resonance circuit; an output-side switching unit for switching four output-side switching devices to convert the secondary voltage to the output DC voltage, the output-side switching unit being connected to the secondary winding of the transformer; and a gate driving circuit for detecting a polarity of secondary current flowing in the secondary winding, generating dead time, generating driving signals for driving the output-side switching device of the output-side switching unit according to the polarity, and then controlling turn-on or turn-off of the output-side switching devices, the gate driving circuit being connected to both the secondary winding of the transformer and the output-side switching unit. According to the synchronous rectifier type SRC, a no-load characteristic can be controlled with an easy scheme and a simple construction. In addition, a simple resistor is added, and thus dead time can be generated. Consequently, it is possible to simply reduce switching loss that may occur in zero voltage switching.

A passive wireless gastroesophageal sensor includes a LC resonance circuit, two or more electrodes and a passive batteryless Radio Frequency Identification (RFID) circuit connected to the LC resonance circuit and the one or more electrodes. The electrodes are configured to measure an impedance within a gastroesophageal tract. The passive batteryless RFID circuit transmits a frequency modulated signal using the LC resonance circuit that varies between a first frequency corresponding to a non-acid reflux condition and a second frequency corresponding to an acid reflux condition based on the measured impedance in response to a signal received from a detector.

An orthogonal modulating circuit for modulating signals of two oscillation frequencies differing in phase by 90° with transmission data (I and Q) is used in common for a plurality of bands, an LC resonance circuit comprising inductances L and a capacitor C is used as the output load on the orthogonal modulating circuit instead of resistors commonly used according to the prior art, and the values of L or C constituting the resonance circuit are switched over between each other according to the transmission band.

Rectifying elements are connected in parallel with switching elements 4-1 through 4-4 in a switching section 4 for the lower voltage side and rectifying elements are connected in parallel with switching elements 5-1 through 5-4 in a switching section 5 for the higher voltage side. An LC resonant circuit 6 is provided between the winding wire 3-2 for the high-voltage side in the transformer 3 and the switching section 5 for the higher voltage side; currents which flows on the primary side and the secondary side is changed into a sinusoidal one; and switching is executed in the vicinity of the zero crossing points of the currents.

The invention relates to an induction cooker control circuit suitable for cookers of different materials. The induction cooker control circuit comprises an IGBT (Insulated Gate Bipolar Translator), an IGBT driving module, an LC (Launch Control) resonance circuit, a central processing unit, a synchronous sampling circuit and a sampling circuit, wherein the LC resonance circuit is connected with the IGBT, and the central processing unit is connected with the IGBT driving module; the synchronous sampling circuit is electrically connected with the LC resonance circuit; and the sampling circuit is connected with the central processing unit and provides current and voltage signals. The control circuit also comprises a resonance frequency sampling circuit which is used for sampling a resonance frequency generated when the cookers of different materials work. The sampling point of the resonance frequency sampling circuit is arranged at the output end of the synchronous sampling circuit, and the output end of the resonance frequency sampling circuit is connected with the central processing unit. The output power and a power preset value are compared and the collected resonance frequency and a resonance frequency preset value are compared to judge whether the resonance frequency is beyond the resonance frequency range of safe working of an induction cooker or not. The output power of an electromagnetic coil is adjusted through the IGBT, so that a main loop working current works in a rated range, and therefore the safe working of the induction cooker is protected.

The invention discloses an antenna for reducing a radar scattering cross section, aiming to solve the problem of large radar scattering cross section of the traditional microstrip antenna. The antenna comprises a dielectric slab (1), a microstrip radiating unit (2) and an earth plate (3), wherein the microstrip radiating unit is arranged at the upper surface of the dielectric slab, and the earth plate is arranged at the lower surface of the dielectric slab; both sides of the microstrip radiating unit are provided with a high impedance surface array (4) respectively; each high impedance surface array is formed by arranging a plurality of metal chips into a rectangle, a gap is arranged between the adjacent metal chips to form a capacitor C; the center of each metal chip is provided with a metal via hole which penetrates through the dielectric slab; a current path connected by the via holes can form an inductor L, and the capacitor and the inductor form an LC resonant circuit; the frequency of the resonant circuit can be adjusted to be coincident with the working frequency of the antenna, thus realizing scattered field compensation of the high impedance surface array and the antenna. The invention has stable performance of reducing radar scattering cross section within and outside the frequency band of the antenna, and also has no effect on the size, weight and cost of the antenna.

The invention relates to a high-efficiency and low-cost forward-flyback DC-DC (direct current-direct current) converter topology. The forward-flyback DC-DC converter topology comprises a transformer, a main switch tube, a clamp circuit, a first rectification switch tube, a second rectification switch tube, an LC resonance circuit and an output capacitor, wherein a primary winding of the transformer is connected in series with the main switch tube between a first input end and a second input end; the clamp circuit consisting of a clamp capacitor and a clamp switch tube which are connected in series is connected in parallel with the primary winding or the main switch tube; a secondary winding of the transformer comprises a forward winding and a flyback winding; one end making the current flow into the primary winding is a dotted end of the primary winding; the secondary side of the transformer is connected in a manner that: the dotted end of the forward winding is connected to the first output terminal through the first rectification switch tube, and the dotted end of the flyback winding is connected to the second output terminal through the second rectification switch tube; the LC resonance circuit is connected to the first output terminal and the second output terminal and the unlike ends of the forward winding and the flyback winding so as to switch on or switch off the first rectification switch tube and the second rectification switch tube at zero current; and the output capacitor is connected between the first output terminal and the second output terminal.

A bidirectional DC/DC converter includes first and second control circuits, and first and second bridge circuits respectively connected to first and second direct current voltage supplies. In one embodiment variant, when power is supplied from the first direct current voltage supply to the second direct current voltage supply, the first control circuit carries out PFM control of the first bridge circuit at a frequency equal to or lower than the resonance frequency of an LC resonant circuit in accordance with a control amount based on the voltage and current of the second direct current voltage supply. When power is supplied in the other direction, the second control circuit carries out fixed frequency control of the second bridge circuit, using phase shift control or the like, in accordance with a control amount based on the voltage and current of the first direct current voltage supply.

Provided are a linearized variable-capacitance module for a voltage-controlled oscillator (VCO) and an LC resonance circuit using the same. The VCO is a circuit for outputting a certain frequency in response to an input control signal (voltage or current). The VCO includes an inductor, a variable capacitor (or a varactor), and an active device for compensating for loss of energy caused by the inductor and varactor. The frequency of the VCO is varied by changing inductance or capacitance. In general, the VCO includes a variable-capacitance device (i.e., the varactor) so that the frequency of the VCO may be varies by changing the capacitance via a control voltage. In most cases, the frequency of the VCO varies nonlinearly with respect to the control voltage. The nonlinear variation in the frequency of the VCO results in a great variation in a VCO gain within a certain control voltage range. When a phase locked loop (PLL) includes the VCO, the variation in the VCO gain leads to a variation in the entire loop gain, thus causing a variation in output phase noise. To solve this problem, a varactor designed to have a capacitance that varies linearly with a control voltage is provided so that a VCO gain can be held constant. The variable-capacitance module includes a plurality of variable-capacitance devices with respectively different linear variation regions on an application voltage axis. Also, the variable-capacitance devices are coupled in common and receive a control voltage at one end while each receiving a different fixed voltage at the other end.

A voltage-controlled oscillator device with an LC-resonant circuit, in particular for implementing integrated voltage-controlled oscillators for the lower GHz range, is disclosed. The device achieves continuous frequency tunability in a wide range in particular with a low level of phase noise and phase jitter. In the voltage-controlled oscillator, a second inductor can be periodically switched in parallel and/or in series with at least one first inductor of the LC-resonant circuit by way of a switching means actuated with the oscillator frequency. A control input of the switching means is connected to a variable dc voltage. In that respect the relationship of the duration of the conducting state and the duration of the non-conducting state of the switching means is variable within an oscillation period of the oscillator in dependence on the value of the control voltage. In accordance with the relationship of the duration of the conducting state and the duration of the non-conducting state of the switching means within an oscillation period of the oscillator the time-averaged effective inductance is variable in dependence on the value of the control voltage.

The invention relates to the technical field of numerical control, in particular to a method for a digital closed-loop control capacitance raising system. In a capacitance acquisition amplifier, the output end of an inductance-capacitance (LC) resonance circuit is connected with the input end of a signal amplifying circuit; in a raiser main control board, the output end of a signal receiving circuit is sequentially connected with the signal input end of a field programmable gate array (FPGA) chip, one input end of a main control board core processor and the other signal end of a servo motor interface circuit; the other two signal ends of the main control board core processor are respectively connected with one end of a human-machine interface and one end of an Ethernet interface in a bidirectional mode; the output end of the signal amplifying circuit is connected with the input end of the signal receiving circuit; and the output end of a magneto-electric conversion circuit of the signal receiving circuit is connected with the signal input end of the FPGA chip. Compared with the prior art, the method has the advantages that: after board capacitance is converted into digital frequency signals, the digital frequency signals are transmitted and measured, so that the method is strong in anti-jamming capability, is not limited by the transmission distance and is high in measurement precision.

An antenna comprises a first conductive layer, a second conductive layer and an LC resonance circuit. The first conductive layer has plural elements and is disposed adjacently to each other. The second conductive layer is disposed at a predetermined distance from the first conductive layer via a dielectric substrate. The LC resonance circuit comprises connection for electrically connecting the elements and the second conductive layer. The LC resonance circuit takes a resonance state in which impedance becomes high in the operating frequency of the antenna. Of the plural elements, a power feeding section is provided in each of any two adjacent elements. Power is fed to the power feeding sections during transmission so that signals of the operating frequency are opposite in phase, and signals of the operating frequency inputted to the antenna are outputted in opposite phase from the power feeding sections during reception.

To provide a DC-DC converter capable of suppressing switching loss with a simple structure, and capable of enhancing converting efficiency.

An LC resonant circuit 3 is inserted on a secondary side of a transformer 1. If switching means 2 is turned ON or OFF by driving means 4, output can be obtained on the secondary side through the transformer 1. A resonant current frequency detecting means comprises a current detecting current transformer 5 and a frequency detecting unit 6. The resonant current frequency detecting means detects resonant current frequency caused by operation of the LC resonant circuit 3. This frequency is fed back to the driving means. As a result, the driving means 4 turns the switching means 2 ON or OFF at a frequency corresponding to the resonant frequency of the LC resonant circuit 3.