52 results about "Impedance modulation" patented technology

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 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 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.

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.

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 loudspeaker has a cooling system in which a pole piece 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 dissipation 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.

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.

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.

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 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.