2461 results about "Input impedance" patented technology

To provide an induced power transmission circuit that transmits, from a transmission antenna (1) connected to a power supply circuit, an AC power having an angular frequency ω to a spaced reception antenna (2) with an excellent efficiency, thereby transmitting it to a load circuit. The induced power transmission circuit comprises a circuit the two ends of which are coupled by a capacitor (C1) and in which the power supply circuit is connected in series to a midway port (1) (P1) of the transmission antenna (1) having an effective self-inductance L1; and a circuit the two ends of which are coupled by a capacitor (C2) and in which the load circuit is connected in series to a midway port (2) (P2) of the reception antenna (2) having an effective self-inductance L2; wherein for a coupling coefficient k of the electromagnetic induction between the antennas and for a phase angle β having an arbitrary value, the angular frequency ω is set to the square root of the reciprocal of a value of L2×C2×(1+k*cos (β)), the output impedance of the power supply circuit is set to approximately kωL1*sin (β), and the input impedance of the load circuit is set to approximately kωL2*sin (β). There is also provided an impedance converting circuit that converts the circuit impedances.

Disclosed is an energy conversion apparatus. An energy conversion apparatus may comprise a control part controlling a length of a first time duration in which input current is inputted and accumulated, a length of a second time duration in which the accumulated current is provided to a load, and a length of a third time duration in which inverse current flows; and a DC-to-DC converter including an inductor, a output capacitor, and at least one switching element, wherein the input current is accumulated during the first time duration by switching the at least one switching element according to a control of the control part so as to perform input impedance matching, and the DC-to-DC convert provides a current corresponding to a difference between the accumulated current provided during the second time duration and the inverse current flowing from the output capacitor during the third time duration to the load.

The power of DC electrical sources is combined onto a DC buss, such that each source behaves independently from any other source attached to the buss. In one embodiment, a converter module is attached to each of a plurality of solar photovoltaic panels and its output is attached in a parallel manner to a common buss that forms the input to a DC AC inverter. The converter module includes a Maximum Power Point Tracking component that matches the output impedance of the panels to the input impedance of the converter module. The converter also includes a communication component that provides parametric data and identification to a central inverter. Data generated by each converter module is transmitted over the power line or by wireless means and is collected at the inverter and forwarded to a data collection and reporting system.

An impedance matching device is provided, for which the electric characteristics at an output terminal are accurately analyzed. The matching device is provided with an input detector for detecting RF voltage and current at the input terminal, and an output detector for detecting RF voltage outputted from the output terminal. The matching device also includes a controller for achieving impedance matching between a high frequency power source connected to the input terminal and a load connected to the output terminal. The impedance matching is performed by adjusting variable capacitors based on the detection data supplied from the input detector. When the impedance of the power source is matched to that of the load, the controller calculates the output impedance, RF voltage and RF current at the output terminal, based on the adjusted capacitances of the capacitors, a pre-obtained reactance-impedance data and the detection data supplied from the output detector.

A transceiver front end circuit includes an antenna terminal capable of being coupled to an antenna. A first balun circuit has a single input that is coupled to the antenna terminal, and a pair of balanced outputs coupled to a corresponding pair of balanced receiver inputs. The first balun circuit matches an input impedance of the pair of balanced receiver inputs and substantially phase shifts the input reflection coefficient of the pair of balanced receiver inputs by about 180-degrees. A second balun circuit has a single output coupled to the antenna terminal and a pair of balanced inputs coupled to a corresponding pair of balanced transmitter outputs. The second balun circuit matches an output impedance of the pair of balanced transmitter outputs and substantially phase shifts the output reflection coefficient of the pair of balanced transmitter outputs by about 180-degrees. The first balun circuit and the second balun circuit can be contained within a single package. A first shunt switch can be coupled across the pair of receiver inputs. A second shunt switch can be coupled across the pair of transmitter outputs.

Planar (two-dimensional) and volumetric (three-dimensional), metamaterial-inspired, efficient electrically-small antennas. The electric-based and magnetic-based antenna systems are shown to be naturally matched to a source and are linearly scalable to a wide range of frequencies. The systems include a radiating element that is fed by the source through a finite ground plane via a feedline and an electrically-small, one-unit cell made of a metamaterial that is adapted to match the input impedance of the antenna.

A multi-band radio module for selectively supplying received signals in a plurality of frequency bands to a low noise amplifier via an input impedance matching circuit by switching over the operation mode of the low noise amplifier is comprised of: a pre-stage amplification unit including a plurality of fundamental amplifiers connected to one another in parallel, the fundamental amplifiers sharing a load impedance connected to a source voltage and a grounded degeneration impedance and having input signal lines commonly connected to an input impedance matching circuit; a post-stage amplifier to which the output signals of the plurality of fundamental amplifiers are commonly inputted; and a bias control unit for selectively turning on the fundamental amplifiers, wherein the input impedance of the low noise amplifier is selectively optimized for the matching circuit depending on the RF band to be received.

An antenna device for transmitting and receiving radio frequency waves, installable in a communication device includes an antenna structure switchable between antenna configuration states. Each state is distinguished by a set of radiation parameters, such as resonance frequency, input impedance, bandwidth, radiation pattern, gain, polarization, and near-field pattern. A switching device selectively switches the structure between the states. The antenna device includes a first receiver which receives a first measured operation parameter indicative of quality of transmission of radio frequency waves by the antenna structure, and a second receiver which receives a second measured operation parameter indicative of quality of reception of radio frequency waves by the structure. The antenna device includes a controller which controls the switching device, and selective switching of the antenna structure between the states, based on the first and second measured operation parameters, to improved transmission and/or reception quality.

A preamplifier having extremely high input impedance amplifies the electrical signal output from an electret condenser microphone (ECM) without suffering from the effects of a DC leakage current at the input. The preamplifier circuit includes a pair of cross-coupled PN junction diodes setting the input impedance, a PMOS device, and a load resistor configured similarly to a conventional preamplifier. A capacitor is placed between the input and the cross-coupled diodes such that a DC path no longer exists to bias the cross-coupled diodes. Therefore, leakage currents are prevented from upsetting the DC operating point of the preamplifier and biasing the cross-coupled diodes. Consequently, small signal gain distortion, excessive demodulation products and increased noise can be avoided.

A radio receiver is described that processes multiple wireless standards using a single antenna according to embodiments of the invention. The radio receiver includes a single antenna, and a low noise amplifier that is connected to the antenna, without an intervening power divider or power splitter. The output of the low noise amplifier feeds multiple wireless receivers in a parallel arrangement that are operating according to different communications standards, including for example a Bluetooth and a WLAN 802.11. Additional wireless standards and their corresponding receivers could be added as well. The input impedance of the low noise amplifier defines the impedance seen by the antenna, regardless of which operational standard is actually in use. Each signal path includes an additional low noise amplifier having a gain that can be customized for the particular signal path and receiver in use, and which also improves the reverse isolation between signal paths. Further, a switch can be added to one or more of the signal paths so as to further improve isolation when a particular path is not being used.

A high-gain and low-noise low noise amplifier (LNA) includes a differential amplifier, a pre-amplifier and an impedance matching network. The differential amplifier includes a first input end and a second input end coupled to a grounded impedance. The pre-amplifier includes an input end and an output end. The impedance matching network is coupled between the first input end of the differential amplifier and the output end of the pre-amplifier for matching an input impedance of the differential amplifier with an output impedance of the pre-amplifier. The present invention provides a LNA structure with low noise, high gain and easy design.

Measuring a neural response to a stimulus comprises applying an electrical stimulus, then imposing a delay during which the stimulus electrodes are open circuited. During the delay, a neural response signal present at sense electrodes is measured with a measurement amplifier, while ensuring that an impedance between the sense electrodes is sufficiently large that a voltage arising on the sense electrode tissue interface in response to the stimulus is constrained to a level which permits assessment of the neural response voltage seen at the sense electrode. For example the input impedance to the measurement amplifier (Z_IN) can be

where Z_C is the sense electrode(s) constant phase element impedance, V_s1−V_s2 is the differential voltage arising on the sense electrode tissue interface, and V_E is the neural response voltage seen at the sense electrode.

Disclosed are in-vivo interstitial antennas (IVIAs) for thermal treatment and deactivation of tumors by means of microwaves. An IVIA comprises a microwave monopole antenna (MMA) and a medical catheter, and the MMA is inserted into the medical catheter to form the IVIA. The MMA comprises coaxial cable and three types of capacitors. The coaxial cable consists of first and second conductors and a first insulator, and only the first conductor extends less than a quarter wavelength. The first capacitor is located around the end of the extended first conductor and includes the second insulator and the third conductor. The second and third capacitors are located between the first capacitor and the apertures of the MMAs and have about same function. Because of arbitrarily changed input impedance of the first capacitor, almost perfect matching can be achieved and desirable temperature distributions can be obtained due to the second and third capacitors.

A programmable variable impedance output driver circuit uses analog biases to match driver output impedance to load input impedance. A current mirror is used to obtain a measurement of an external resistance value for matching the impedance of a driven load. The mirrored current generates the voltage "NBIAS" when passed through the resistively connected NFET. Similarly, the current is again mirrored and passed through a resistively connected PFET resulting in the voltage "PBIAS". The analog bias voltages, NBIAS and PBIAS are used to vary the impedance of complementary FETs in an impedance matched driver for a high degree of dI/dt control. The driver provides a high degree of flexibility because its turn-on and turn-off characteristics do not depend on a combination of digital control signals connected directly to the driving FETs as in the prior art. Instead, the PBIAS and NBIAS signals provide analog controls which may be applied to single transistors whose impedance changes as PBIAS and NBIAS increase or decrease.

An electrosurgical system including or connected to an output circuitry comprising an electrosurgical device and an electrical cable is modelled during a cable interrogation phase using a transfer matrix in order to determine a leakage capacitance in the electrosurgical system. After the leakage capacitance is assigned or set to a virtual capacitor in the transfer matrix, an output parameter of the electrosurgical system, such as output voltage, output current, output impedance or output electrical power, may be determined by applying an actual input voltage to the output circuitry and measuring a resulting input current, and multiplying the input voltage and measured current by the transfer matrix.

A living body measuring sensor (1) is made to contact a body surface of a measuring subject through capacitance coupling using a cloth (6) between a metal electrode (2) and the body surface as the capacitance, a living body electric signal is extracted from the metal electrode (2), and an elctrocardiographic waveform is outputted based on an output of the living body measuring sensor (1) using an impedance converter having a high input impedance and a low output impedance.

A compact four-way waveguide power divider (10). The inventive power divider (10) includes an input waveguide (11) that terminates at a junction with two adjacent waveguides on opposite sides of the input waveguide. On the opposite side of the junction is a conducting wall into which is built an inductive septum (20). The inductive septum (20) serves to partially match the input impedance of the structure. Second and third inductive septums (22 and 24) are also built into the output arms of the power divider (10). The purpose of the second and third septums (22 and 24) is twofold. In addition to partially matching the power divider's input impedance, the positions of the second and third septums (22 and 24) can be adjusted to equalize the power division between the output arms. Hence, the waves exiting the four output arms of the power divider have highly equalized amplitudes and phases. Further, the phases at the output ports are equalized by adjusting the lengths of the output arms. The use of offset inductive septums (22 and 24) in the output arms to achieve equalized power division allows the input and output waveguides to be placed in very close proximity, resulting in an extremely compact structure.

A wireless power transmitter for transmitting power to a wireless power receiver in a wireless scheme includes a transmitting coil configured to transmit power, which is supplied by a power source, to a receiving coil of the wireless power receiver using resonance; and a detecting unit configured to detect a coupling state between the transmitting coil and the receiving coil using an input impedance of the wireless power transmitter.

An integrated device includes a voltage mode transmit driver for matching an output impedance to an output transmission line based on a binary code, an input termination module configured for matching an input impedance to an input transmission line based on an input impedance calibration value using thermometer-based decoding. The voltage mode transmit driver includes, for each differential output signal, a resistor network circuit having pull-up circuits and pull-down circuits for changing the voltage on the differential output signal, and having binary weighted resistance values relative to each other. The input termination module includes pull-up circuits and pull-down circuits having inverse hyperbolic resistance values relative to each other, and using thermometer-based decoding to ensure a linear change in input impedance during transitions in the input impedance calibration value. A calibration circuit generates the binary code and the input impedance calibration value based on replicas of the pull-up and pull-down circuits.

Power transfer rate at a charging facility can be maximized by employing a feedback scheme. The state of charge (SOC) and temperature of the regenerative energy storage system (RESS) pack of a vehicle is monitored to determine the load due to the RESS pack. An optimal frequency that cancels the imaginary component of the input impedance for the output signal from a grid converter is calculated from the load of the RESS pack, and a frequency offset f* is made to the nominal frequency f₀ of the grid converter output based on the resonance frequency of a magnetically coupled circuit. The optimal frequency can maximize the efficiency of the power transfer. Further, an optimal grid converter duty ratio d* can be derived from the charge rate of the RESS pack. The grid converter duty ratio d* regulates wireless power transfer (WPT) power level.