52 results about "Impedance modulation" patented technology

The disclosed means of determining alignment between an external charger and an implantable medical device (IMD) involves the use of reflected impedance modulation, i.e., by measuring at the external charger reflections arising from modulating the impedance of the charging coil in the IMD. During charging, the charging coil in the IMD is pulsed to modulate its impedance. The difference in the coil voltage (ΔV) produced at the external charger as a result of these pulses is assessed and is used by the external charger to indicate coupling. If the magnitude of ΔV is above a threshold, the external charger considers the coupling to the IMD to be adequate, and an alignment indicator in the external charger is controlled accordingly. The magnitude of Vcoil can be assessed in addition to ΔV to determine alignment with the IMD with improved precision, and / or to further define a high quality alignment condition.

A power amplifier controller circuit controls an adjustable impedance matching network at the output of a power amplifier to vary its load line to improve the efficiency of the RF PA. The PA controller circuit comprises an amplitude control loop that determines an amplitude correction signal. The amplitude loop is configured to control or correct for distortion from the adjustable matching network based upon the amplitude correction signal.

The present invention relates to an impedance modulation device for an orthotic application. The device includes a high-stiffness loading spring, a low-stiffness return spring, a shaft having an output connector, and an engagement mechanism. When the engagement mechanism engages the shaft, the device exhibits a high stiffness at the output connector, and wherein when the engagement mechanism disengages the shaft, the device exhibits a low stiffness at the output connector.

A power amplifier controller circuit controls an adjustable impedance matching network at the output of a power amplifier to vary its load line to improve the efficiency of the RF PA. The PA controller circuit comprises an amplitude control loop that determines an amplitude correction signal. The amplitude loop is configured to control or correct for distortion from the adjustable matching network based upon the amplitude correction signal.

A standby circuit is provides to on / off a power converter for power saving. The standby circuit includes a comparison circuit. The comparison circuit is coupled to a feedback loop of the power converter to generate a mode signal when a feedback signal of the feedback loop is lower than a threshold signal. A resistive device is coupled to the feedback loop. The resistance of the resistive device is increased in response to the mode signal. The mode signal is further coupled to turn off a switching control circuit of the power converter.

A loudspeaker has a cooling system in which a pole portion has a shorting ring made of non-magnetic conductive material that stabilizes magnetic field to reduce distortion of sound and a heat dissipation plate that couples to the shorting ring to facilitate efficient dissipation of heat. The heat generated by a voice coil of the loudspeaker is transmitted to the shorting ring and is conducted to the heat dissipation plate which acts as a heat sink to allow the heat dissipation. A multiplicity of shorting rings may be provided to further reduce impedance modulation, each of which is coupled to the heat plate. The heat dissipation plate has a gap in an axial direction of the loudspeaker to prevent an electric current in the shorting ring from flowing through the heat dissipation plate.

The invention discloses a holographic modulation based artificial tensor impedance surfaced antenna and an implementation method thereof. The artificial tensor impedance surfaced antenna systematically comprises an artificial tensor impendance surface composed of multiple unit lattices equal in size; each unit lattice sequentially comprises a metal floor, a dielectric substrate and a metal paster from top to bottom; surface impedance corresponding to the unit lattices of the artificial tensor impedance surface is controlled through geometric parameters of the metal paster, so that the surface impedance on the surface of the antenna is distributed according to holographic interference pattern rules of a source field and a target field. The implementation method includes the steps of S1, scalar impedance extraction and simulation; 2), matching of equivalent scalar surface impedance curves; S3, holographic modulation of the sensor surface impedance; S4, antenna modeling and simulation. The target radiation field of a specific planning mode is obtained by the aid of the holographic tensor surface impedance principle, an equivalent scalar surface impedance matching criterion is put forward, and data volume needed in modulation of the tensor surface impedance is effectively reduced.

An absolute scale configuration is provided for use in a position encoder which includes a readhead and a scale. The absolute scale configuration includes a plurality of scale loops distributed along a measuring axis to provide a position dependent signal that varies depending on a relative position between the scale loops and the readhead. At least some of the scale loops are coupled to respective impedance modulating circuits connected to receive energy from current induced in the scale loop and to provide a unique coded modulation of the scale loop impedance during a code signal generating state. The unique coded modulations as sensed by the readhead are indicative of a coarse resolution absolute position, which may be utilized in combination with the position dependent signal to determine an absolute position with a high resolution.

A power amplifier controller circuit controls an adjustable impedance matching network at the output of a power amplifier to vary its load line to improve the efficiency of the RF PA. The PA controller circuit comprises an amplitude control loop that determines an amplitude correction signal. The amplitude loop is configured to control or correct for distortion from the adjustable matching network based upon the amplitude correction signal.

A feedback circuit with feedback impedance modulation according to the present invention comprises a compare circuit, a counter and a switching resistor circuit. The compare circuit receives a feedback signal of a power converter to compare the feedback signal with a threshold signal for generating a control signal. The feedback signal is correlated to a load condition of the power converter. The counter is coupled to the compare circuit and generates a modulation signal in response to the control signal. The switching resistor circuit is coupled to the counter and a feedback loop of the power converter for modulating a feedback impedance of the power converter in response to the modulation signal. The feedback impedance is directly modulated from a lower resistance to a higher resistance when the load condition is reduced from a half / full-load to a no / light-load. The feedback impedance is gradually modulated from a higher resistance to a lower resistance when the load condition is increased from the no / light-load to the half / full-load.

An absolute scale configuration is provided for use in a position encoder which includes a readhead and a scale. The absolute scale configuration includes a plurality of scale loops distributed along a measuring axis to provide a position dependent signal that varies depending on a relative position between the scale loops and the readhead. At least some of the scale loops are coupled to respective impedance modulating circuits connected to receive energy from current induced in the scale loop and to provide a unique coded modulation of the scale loop impedance during a code signal generating state. The unique coded modulations as sensed by the readhead are indicative of a coarse resolution absolute position, which may be utilized in combination with the position dependent signal to determine an absolute position with a high resolution.

The invention discloses a broadband high-efficiency power amplifier with active load modulation and belongs to the key technology of broadband high-efficiency power amplifiers in transmitters. An active load impedance modulation method is provided for the power amplifier, and a transistor is allowed to obtain optimal load impedance in the work band width indirectly through a matching network. According the application experience of a Doherty power amplifier, the used active load modulation technology can manually change the visual-in impedance of one node in a circuit. Therefore, the active load modulation technology can also be used for eliminating the impedance errors of inactive network matching when the power amplifier works under ultra-wide band, the optimal impedance needed by a power amplifier end face can be achieved by the aid of the technology, and the power amplifier can efficiently work in large band width.

The invention provides a conformal surface wave antenna based on a holographic metasurface. The conformal surface wave antenna comprises a monopole feed source and a holographic impedance surface, theholographic impedance surface comprises m*n periodically arranged impedance surface units, each impedance surface unit comprises a dielectric plate, a square metal patch printed at the center position of the upper surface of the dielectric plate and a metal floor arranged at the lower surface of the dielectric plate, the surface impedance of each impedance surface unit is distributed based on theinterference pattern of a holographic principle, the reference waves corresponding to the distribution of the interference patterns are cylindrical surface waves generated by the monopole feed source, and a target wave is a radiation plane wave in the endfire direction of the holographic impedance surface. Directed radiation is achieved in the endfire direction of the conformal surface wave antenna prior to generation of the cylindrical surface waves, which are subjected to impedance modulation of the holographic impedance surface, by employing the monopole feed source to form a flat plane wave, and when a conformal surface wave antenna meets a curved surface bulge, diffraction propagation of the surface wave can be achieved.

An intravascular guidewire with integrated imaging and pressure measurement capabilities is disclosed. The guidewire can comprise an integrated CMUT-on-CMOS ultrasound transducer array to provide 3D imaging of vasculature and other tissue. The guidewire can also comprise a conventional FFR pressure sensor or Doppler flow sensor. Due to the low power consumption of the chip, power can be provided via a single pair of wire pair proximate the core wire of the guidewire to provide power and ground to the chip. The system can also include a power wire, a ground wire, and a data wire, the data wire using similar data transmission techniques. Data from the sensor array can be transmitted over the power wire using, for example, RF or impedance modulation. Data can also be transmitted through the body using an ultra wideband wireless transmitter and flexible patch antenna on the skin.

A control circuit is provided to generate a mode signal at light load of the power converter. The mode signal is coupled to disable the switching signal for saving power. The impedance of an input circuit is increased in response to the mode signal. Furthermore, a soft start circuit is initiated by the mode signal when switching signal is enabled. An external capacitor associates with the impedance of the input circuit determine the off period of the switching signal.

An active element array substrate and display panel operation method is disclosed. An active element array substrate comprises a substrate, a data line, and a repair line. The substrate has a display area, a first peripheral region and a second peripheral region, wherein the first peripheral region and the second peripheral region are respectively provided on opposite sides of the display region. The data line is provided at least in the display area of the substrate and extends to the first peripheral region and the second peripheral region. The repair line comprises at least one impedance modulation circuit, a first repair line segment and a second repair line segment. The impedance modulation circuit has an input terminal, an output terminal and a control terminal, wherein the impedance modulation circuit is used to adjust the impedance according to the control signal received by the control terminal. The first repair line is electrically coupled to the input and extends to the first peripheral region of the substrate. The second repair line is electrically coupled to the output and extends to the second peripheral zone of the substrate.

The invention discloses a dual-beam frequency scanning leaky-wave antenna. The dual-beam frequency scanning leaky-wave antenna is composed of a dielectric substrate, a top metal panel, a bottom metalpanel and a metal tube, a half-mode substrate integrated waveguide structure is adopted, based on the periodic sine impedance modulation principle, a double-period sine impedance modulation groove isformed in the top metal panel to serve as a radiation unit, and due to the fact that the top metal panel is formed by superposing sine impedances of two kinds of single beams, beams in two radiation directions can be generated; a periodically changing groove is also arranged on the bottom metal panel as a radiation unit, so that the radiation efficiency of the antenna can be improved, the stop band effect of the periodic leaky-wave antenna can be inhibited, and compared with the traditional double-beam frequency scanning antenna, the dual-beam frequency scanning leaky-wave antenna has the characteristics of simple structure, narrow bandwidth, large scanning angle and the like.

The invention belongs to the technical field of wireless communication, specifically a transformer parallel synthesis-based power amplifier. The transformer parallel synthesis-based power amplifier comprises a transistor level active part and a transformer parallel synthesis-based passive network part. The active part is realized through adoption of a power amplifier of a voltage-mode pure analog,digital and analog mixed or all digital type. The passive part realizes parallel power synthesis, load impedance modulation and differential to single-ended conversion. According to the transformer parallel synthesis-based power amplifier, a power modulator module is removed; and for broadband application, the processing capacity far higher than a signal bandwidth is avoided. Compared with a traditional back-off efficiency enhanced power amplifier, the transformer parallel synthesis-based power amplifier has the advantages that quarter-wave transmission lines or a plurality of transformer forimpedance conversion are avoided, and only an area of the single transformer is occupied. The transformer parallel synthesis-based power amplifier is concise in structure and compact in area. The relatively high efficiency can be kept in a relatively wide output power range. The transformer parallel synthesis-based power amplifier is applicable to low cost and high efficiency demands of high peakaverage power ratio communication applications such as NB-IoT, LTE, a WLAN and 5G.

The invention provides an electronic load device and a simulation method thereof. The electronic load device is used for simulating a circuit unit to carry out a loading test on a power supply device. A power consumption unit is connected with the power supply device to load the power supply device; a voltage measurement unit is connected between the power consumption unit and the power supply device and measures a first-time voltage value inputted by the power consumption unit loading the power supply device at a first time; a digital signal processor unit stores and sets the impedance parameter of the circuit unit, receives the first-time voltage value measured by the voltage measurement unit, utilizes the mathematical model of the circuit unit to work out a current value according to a first-time input current value of the first time, then works out a second-time voltage value and a second-time current value according to the impedance parameter of the circuit unit and then outputs an impedance modulation signal to the power consumption unit, so that on-load current is outputted and regulated. Hardware equipment is saved, the circuit structure is simplified, the equipment cost is reduced, and accumulated errors are eliminated.

A plasma generating apparatus is provided. The plasma generating apparatus includes a plasma process chamber, a top electrode board, a bottom electrode board and at least one pair of impedance modulators. The top electrode board is coupled to a radio frequency (RF) power source. The impedance modulators are provided in pairs and are parallel-connected to the top electrode board at two geometrically symmetrical locations, wherein each impedance modulator has an impedance modulation curve whose value changes with time, and the value of a parallel equivalent impedance curve of the impedance modulation curves is constant with time.

The invention relates to optical impedance modulation for fuel quantity measurement. Provided are an optical impedance fluid level sensor that eliminates electricity for measuring fuel quantity in fuel tanks, as well as a system and method using the sensor. The optical impedance sensor comprises two optical fibers spaced apart inside a meniscus tube, one to transmit light along its length and the other to receive light along its length. The meniscus tube minimizes the sloshing of fuel level. The fuel level in the tank modulates the optical impedance between the two optical fibers, resulting in changes in the total light received by an optical detector. Depending on fuel tank height, the optical impedance sensor may comprise different embodiments in which the detection apparatus shapes the light to be unidirectional, with light emitted and collected only on one side of the fibers, or omnidirectional, comprising all directions around the optical fibers.

The invention discloses a broadband microwave coaxial automatic impedance modulator, and belongs to the technical field of microwave impedance modulators. The modulator comprises a standing wave detection module, a frequency detection module, an impedance modulation module, a microprocessor module and a driving motor. The standing wave detection module is used for measuring the amplitude and the phase of a reflection coefficient in a coaxial main transmission line. The frequency detection module is used for measuring the current working frequency. The microprocessor calculating module is usedfor reading the reflection coefficient and the working frequency, and then calculating to obtain the lengths of two coaxial matching branch sections in order to match with the system. Furthermore, thelength required by the matching of the system is converted into the positions of two short-circuit sliding blocks and then the positions of the two sliding blocks are adjusted through the driving motor. Therefore, the automatic matching of the impedance is achieved. The defect that the working bandwidth is narrow due to the dispersion effect in the prior art is overcome. The working bandwidth ofthe automatic impedance matching device is greatly expanded on the basis of ensuring the power capacity and the distribution range.

The invention discloses a periodic impedance modulation surface for rectangular beam forming of any pitching surface, and belongs to the technical field of antennas and periodic impedance modulation surfaces. According to the periodic impedance modulation surface, the periodic impedance modulation surface is applied to rectangular beam forming, compared with an existing technology combining array synthesis and algorithm, multiple feed sources and a complex feed network do not need to be adopted, only the inner core of the coaxial line needs to be prolonged to form a monopole for feeding, the structure is simple, and implementation is easy. A method has another advantage that compared with an existing method for achieving rectangular beam forming in the normal direction, rectangular beam forming can be achieved in the direction with a certain inclination angle.

The invention discloses a reconfigurable holographic impedance modulation surface antenna based on a laminated structure and liquid crystal. The antenna comprises a dielectric frame, and a metal bottom plate is arranged below the dielectric frame; a groove body penetrating through the upper and lower surfaces of the medium frame is formed in the medium frame, a liquid crystal layer is arranged in the groove body, and a dielectric plate is arranged on the liquid crystal layer; and the upper surface and the lower surface of the dielectric plate are each provided with eight laminated structure periodic slot units which are sequentially arranged, and each laminated structure periodic slot unit comprises four metal through holes penetrating through the dielectric plate, seven metal patches and two longitudinal metal strips located on the bottom face of the dielectric plate. According to the invention, a surface impedance extraction method is adopted to obtain the laminated structure periodic slot units, then the liquid crystal layer is loaded in the dielectric frame, and voltage bias regulation and control are carried out on the liquid crystal layer, so that the laminated structure reconfigurable periodic slot units are formed, and the reconfiguration of the directional diagram is realized.

The invention discloses a high-gain low-cross-polarization holographic impedance modulation surface antenna design method and an antenna. The design method includes following steps: building a simulation model of a lattice unit of a square metal patch structure to acquire a surface impedance value; establishing a mathematic relation between metal patch geometric parameters and the surface impedance value; establishing a holographic surface modulation formula, and modulating surface impedance to acquire surface impedance distribution in an antenna plane; on the basis of the mathematic relation and the surface impedance distribution, calculating to acquire a patch parameter value of each point in the antenna plane, and building a model of a whole holographic impedance modulation surface antenna; arranging an edge portion of the model to be of a gradually-changing structure. By adopting a holographic impedance modulation surface antenna form of the gradually-changing structure, gain of the antenna can be increased effectively, cross polarization can be lowered, and overall performance of the antenna is improved.

The invention relates to an impedance modulation damage detection method for a fatigue crack. An NI system and a self-made self-sensing circuit are used to carry out impedance measurement, so the costof the method in the invention is greatly less than that of traditional impedance meter measurement, and the method is suitable for various environments and conditions, can effectively detect the damages of nonlinear fatigue cracks, ensures that the nonlinear fatigue crack damages of a structure can be timely founds, does not need measurement of a reference signal in the healthy state of the structure, is not affected by environment factors, such as the temperature, can complete the measurement only through one piezoelectric plate, and reduces the complexity and the measurement cost of fatigue crack damage detection.

The invention discloses a high gain holographic impedance modulation surface antenna design method and an antenna. The method comprises steps of S1, establishing a model of a lattice unit based on a circular metal patch; S2, fitting the mathematical relationship between a geometric parameter and a surface impedance value between a distance g of a circular metal patch from an edge of the lattice unit and the surface impedance Z; S3, obtaining surface impedance distribution of the holographic impedance modulation surface; and S4, calculating a parameter value of the circular metal patch of the holographic impedance modulation surface and establishing a model of the entire holographic impedance modulation surface. The method is advantaged in that through the holographic impedance modulation surface antenna form of the step structure, the gain of the antenna can be effectively improved, radiation deviating from the normal direction is realized, overall performance of the antenna is improved, moreover, the holographic impedance modulation surface antenna has a planar structure, no additional introduction of a feed source and the feed network is required, the structure is simple, bandwidth is wide, and radiation deviating from the normal direction can be further realized.