Aspects of the present disclosure generally relate to a RF high power amplifier designed for resonance mitigation. A method for resonance mitigation in RF high power amplifier enclosure and an enclosure for RF high power amplifier designed to mitigate resonance is provided. In an aspect, the enclosure can be configured with a metallic post or a grounded metallic post positioned at a suitable location with RF high power amplifier circuit to dampen and shift out resonance. In an aspect, the metallic post can be placed between printed circuit board (PCB) substrate and enclosure lid. Proposed metallic post solution eliminates the need of RF absorber in the design.

Apparatus and methods for orienting power amplifiers are disclosed herein. In certain implementations, a power amplifier system is provided. The power amplifier system includes a first power amplifier die that is positioned in a first position on a printed circuit board (PCB) and configured to radiate a first amount of emissions. The power amplifier system further includes a second power amplifier die that is positioned in a second orientation on the PCB and configured to radiate a second amount of emissions. The power amplifier system further includes a third power amplifier die that is positioned in a third orientation on the PCB and configured to radiate a third amount of emissions, the third power amplifier die oriented such that the first amount of emissions, the second amount of emissions, and the third amount of emissions in a first direction are less than a threshold value.

A low power amplifier architecture that employs a single-ended (single triode) push-pull (SEPP) vacuum tube and output transformer arrangement, and that cancels unwanted amplifier signal components such as hum and noise. The SEPP amplifier operates to cancel power supply ripple and local EMI induced noise in the output transformer by providing reverse polarity of the primary coils of the output transformer.

A power amplifier without transformer includes an audio isolator, a phase detector, a power protection controller, a rectifier and an amplifier. The audio isolator is used to isolate audio-source input end and the amplifier for making the amplifier directly connected to utility power via the rectifier without transformer to increase transformation efficiency and decrease weight and bulk of the power amplifier substantially. The phase detector is used to detect utility power phase whether correct. The power protection controller is used to determine utility power whether supply to the amplifier for preventing the amplifier from broken caused by excessive current.

A wireless power transmitter includes an amplifier configured to amplify a power; a transmitter configured to resonate the power amplified by the amplifier; and a reference signal provider configured to provide a reference signal to the amplifier and change a frequency of the reference signal.

Apparatus and methods for orienting power amplifiers are disclosed herein. In certain implementations, a method of determining the physical orientation of power amplifiers laid out on a printed circuit board (PCB) is provided. The method includes determining an amount of emissions radiated by a first power amplifier die that is positioned in a first orientation on the PCB. The method further includes determining an amount of emissions radiated by a second power amplifier die that is positioned in a second orientation on the PCB. The method further includes determining a third orientation of the second power amplifier die different than the second orientation, such that when the second power amplifier die is in the third orientation, the amount of emissions radiated by the first power amplifier die and the amount of emissions radiated by the second power amplifier die are distributed in different directions.

Apparatus and methods for orienting power amplifiers are disclosed herein. In certain implementations, a power amplifier system is provided. The power amplifier system includes a first power amplifier die that is positioned in a first position on a printed circuit board (PCB) and configured to radiate a first amount of emissions. The power amplifier system further includes a second power amplifier die that is positioned in a second orientation on the PCB and configured to radiate a second amount of emissions. The power amplifier system further includes a third power amplifier die that is positioned in a third orientation on the PCB and configured to radiate a third amount of emissions, the third power amplifier die oriented such that the first amount of emissions, the second amount of emissions, and the third amount of emissions in a first direction are less than a threshold value.

Apparatus and method for establishing a stable operating point of a H-bridge with a center shunt switch. The stable operating point lets a circuit connected to the H-bridge outputs work in a more ideal condition. As such, an H-bridge with a stable operating point will yield a higher performance and/or save power. Since common mode is one of the biggest sources of electromagnetic interference, a stable operating point in an H-bridge also suppresses EMI.

An audio signal modulation and amplification circuit includes a common-mode electric potential controller, a carrier generator, and channel circuits. The common-mode electric potential controller is configured to generate one or more first common-mode electric potentials and second common-mode electric potentials. The carrier generator is adapted to receive the first common-mode electric potential to generate a carrier signal. Each of the channel circuits includes a filter, a comparison circuit, and a driving circuit. The filter is adapted to filter an input signal and generate a filtered signal based on a corresponding one of the second common-mode electric potentials. The comparison circuit is configured to compare the potential of the carrier signal with the potential of the filtered signal to generate a pulse-width modulation signal. The driving circuit is configured to be turned on or off in response to the pulse-width modulation signal to output a load driving signal.

Aspects of this disclosure relate to a cancelling interference at an output of a power amplifier. An interference sensing circuit in a signal path between the power amplifier and an antenna can generate an interfering power signal. An interference cancellation loop can receive the interfering power signal and provide a cancellation signal to a transmit signal path that includes the power amplifier to thereby suppress interference at the output of the power amplifier. In certain embodiments, the interference cancellation loop includes an amplifier and a phase shifter. Related systems and methods are disclosed.