An outphasing amplifier includes a first class-E power amplifier (16-1) having an output coupled to a first conductor (31-1) and an input receiving a first RF drive signal (S.sub.1(t)). A first reactive element (C.sub.A-1) is coupled between the first conductor and a second conductor (30-1). A second reactive element (L.sub.A-1) is coupled between the second conductor and a third conductor (32-1). A second class-E power amplifier (17-1) includes an output coupled to a fourth conductor (31-2) and an input coupled to a second RF drive signal (S.sub.2(t)), a third reactive element (C.sub.A-3) coupled between the second and fourth conductors. Outputs of the first and second power amplifiers are combined by the first, second and third reactive elements to produce an output current in a load (R). An efficiency enhancement circuit (L.sub.EEC-1) is coupled between the first and fourth conductors to improve power efficiency at back-off power levels. Power enhancement circuits (20-1,2) are coupled to the first and fourth conductors, respectively.

A power amplification module includes: an amplifier that amplifies an input signal and outputs an amplified signal; and a harmonic-termination circuit to which harmonics of the amplified signal are input and the impedance of which is controlled in accordance with the frequency of a harmonic. The power amplification module can operate in a first mode in which a power supply voltage changes in accordance with the average voltage value of the amplified signal over a prescribed time period or in a second mode in which the power supply voltage changes in accordance with the envelope of the input signal. The impedance of the harmonic-termination circuit is controlled such that at least one even-ordered harmonic is short-circuited when the power amplification module operates in the first mode and at least one odd-ordered harmonic of third order or higher is short-circuited when the power amplification module operates in the second mode.

A wireless power transmitter includes an inverter in which a voltage varies in response to a resonant network and circuitry configured to (A) measure a characteristic indicative of a load seen by the wireless power transmitter, (B) determine a duty cycle of the inverter based upon the characteristic, and (C) switch the inverter with the determined duty cycle.

A control method of controlling a resonance type power conversion device including a voltage resonance circuit is provided. The voltage resonance circuit comprising, a choke coil connected to input power supply, a first switching element connected to the choke coil, a capacitor connected in parallel to the first switching element, and a resonance circuit connected between a connection point and an output terminal, the connection point being a point at which the choke coil and the first switching element are connected. The control method comprising, detecting a polarity of current flowing through parallel circuit connected in parallel to the first switching element by using a sensor included in the voltage resonance circuit; and controlling an operating condition of the first switching element depending on a polarity of the current detected by the sensor.

The present invention relates to an amplifying device and to an amplifying system comprising the same. According to the present invention, an amplifier line-up is presented comprising four amplifying units which is operable in a Doherty mode and an outphasing mode. By integration of Chireix compensating elements in the matching networks used in the amplifying units a bandwidth improvement can be obtained.

Methods and apparatus provide compensation for impedance changes in a network energized by an amplifier, such as a class E amplifier. In embodiments, bus voltage amplifier fundamental AC output voltage can be used to generate a feedback signal for adjusting impedance of one or more components in the network. In embodiments, the amplifier fundamental AC output voltage is determined from current to the load, wherein the load is coupled to the amplifier by an LCL impedance matching network.

A power amplifying circuit includes a bias circuit that supplies a bias current or a bias voltage to a base of a first transistor, and at least one termination circuit that short-circuits a second-order harmonic of an amplified signal output from a collector of the first transistor to a ground voltage. An emitter of the first transistor is connected to ground. The bias circuit includes a second transistor. A collector of the second transistor is connected to the base of the first transistor. An emitter of the second transistor is connected to the emitter of the first transistor. A base of the second transistor is supplied with a predetermined voltage.

Disclosed is an RF (Radio Frequency) power source having a power supply configured to convert an AC (Alternating Current) voltage at a power supply input to a second voltage at a power supply output, and an RF generator configured to receive the second voltage at an RF generator input and to use the second voltage to produce an output RF signal at an RF generator output. According to an embodiment of the disclosure, the power supply performs the voltage conversion without galvanic isolation between the power supply input and the power supply output, which can increase energy efficiency while reducing complexity and cost as well. Instead, the RF generator is provided with galvanic isolation between the RF generator input and the RF generator output, which can be sufficient for achieving galvanic isolation between the power supply input and the RF generator output for safety reasons.

A control circuit and a method for controlling a piezoelectric transformer are disclosed. In an embodiment the control circuit includes an inductor and a control unit, wherein the control circuit is configured to apply a voltage with a periodic waveform to a piezoelectric transformer, wherein a period duration of the voltage is specified by a control frequency and adjust the control frequency of the applied voltage as a function of an average current intensity of a current flowing through the inductor.

Systems, methods and apparatus for wireless charging are disclosed. A charging apparatus has an amplifier stage, a power switching stage and a controller. The amplifier stage has a choke that receives a current from an input of the amplifier stage, a resonant network coupled to an output of the choke and that provides an output current to a load, and a first switch configured to short the output of the choke to circuit ground when turned on. The power switching stage may be configured to couple a power supply to the input of the amplifier stage and may have a second switch operable to couple the input of the amplifier stage to circuit ground when turned on. The controller may be configured to control operation of the first switch and the second switch in accordance with a timing sequence that defines a cycle of the output current.