An audio processing system is described including an amplifier configured to receive a first audio signal and output the first audio signal to an acoustic transducer comprising a voice coil. A sensor detects a signal corresponding to voice coil current of the acoustic transducer. A controller compares the first audio signal and the detected signal and determines a second audio signal from the comparison. The second audio signal is representative of an external sound source detected via the acoustic transducer. The audio processing system may simultaneously output the first audio signal and receive the second audio signal using the same acoustic transducer.

An integrated circuit for measuring current while receiving wireless power is described. The integrated circuit measures a current across a resistor by an amplifier. A gain of the amplifier is based on a pair of matched upstairs resistors and a pair of matched downstairs resistors. The pair of matched upstairs resistors may include an offset in resistance. The integrated circuit includes a switch matrix with switches coupled between the integrated resistor and the pair of matched upstairs resistors. The offset for the pair of matched upstairs resistors may be measured by selectively controlling the switches.

A load independent inverter comprises a switched mode zero-voltage switching (ZVS) amplifier. The switched mode ZVS amplifier comprising: a pair of circuits comprises: at least a transistor and at least a capacitor arranged in parallel; and at least an inductor arranged in series with the transistor and capacitor. The amplifier further comprises only one ZVS inductor connected to the pair of circuits; and at least a pair of capacitors connected to the ZVS inductor and arranged in series with at least an inductor and at least a resistor.

A method for controlling a signal envelope shape of modulation pulses in a driver of a wireless transmitter includes supplying a first voltage to the driver during a non-modulated state, supplying a second voltage configurable by a configurable modulation index value to the driver during a modulated state, switching between the non-modulated state and the modulated state comprising setting the modulation index value to configure the second voltage level at the same level as the first voltage and then switching between supplying the first voltage to the driver and supplying the second voltage to the driver, and filtering to a limited bandwidth the variations of the second voltage resulting from configuring the modulation index value.

A method for controlling a signal envelope shape of modulation pulses in a driver of a wireless transmitter includes supplying a first voltage to the driver during a non-modulated state, supplying a second voltage configurable by a configurable modulation index value to the driver during a modulated state, switching between the non-modulated state and the modulated state comprising setting the modulation index value to configure the second voltage level at the same level as the first voltage and then switching between supplying the first voltage to the driver and supplying the second voltage to the driver, and filtering to a limited bandwidth the variations of the second voltage resulting from configuring the modulation index value.

Methods and systems for power amplification with digital quantized power supply with multiple amplifiers are disclosed herein. In one embodiment, In one embodiment, a time-varying envelope signal is sampled, quantized and decomposed into several constituent signals that are individually amplified, and then combined to form a desired amplified version of the quantized time-varying envelope. Amplitude, phase and/or frequency characteristics of one or more of the signals and supply voltages V.sub.dd and source current of one or more amplifiers are digital controlled based on the information provided by quantization process and slow and fast power control information. Amplitude, phase and/or frequency characteristics of one or more of the constituent signals to be amplified are controlled to provide the desired amplitude, phase, frequency, and/or spectral characteristics of the desired quantized version of the time-varying envelope signal.

Systems, devices and methods related to multi-band power amplifier. In some embodiments, a power amplifier module includes a power amplifier having an output stage and configured to receive a signal. The power amplifier module also includes a first programmable harmonic termination circuit in electrical communication with the output stage of the power amplifier. The first programmable harmonic termination circuit includes a first plurality of capacitors and a first plurality of switches, with at least one of the first plurality of capacitors being in electrical communication with at least one of the first plurality of switches. The power amplifier module further includes a controller configured to modify a configuration of the first plurality of switches of the first programmable harmonic termination circuit based at least in part on a second harmonic frequency of the signal.

Systems, devices and methods related to multi-band power amplifier. In some embodiments, a power amplifier module includes a power amplifier having an output stage and configured to receive a signal. The power amplifier module also includes a first programmable harmonic termination circuit in electrical communication with the output stage of the power amplifier. The first programmable harmonic termination circuit includes a first plurality of capacitors and a first plurality of switches, with at least one of the first plurality of capacitors being in electrical communication with at least one of the first plurality of switches. The power amplifier module further includes a controller configured to modify a configuration of the first plurality of switches of the first programmable harmonic termination circuit based at least in part on a second harmonic frequency of the signal.

An amplifier comprises eight transistors: the first coupled to a linked node and to a positive output node, the second coupled to the linked node and to a negative output node, the third coupled to the positive output node and a common potential, the fourth coupled to the negative output node and the common potential, the fifth coupled to a battery node, the sixth coupled to the fifth transistor and to the positive output node, the seventh coupled to the battery node, and the eighth coupled to the seventh transistor and to the negative output node. The amplifier also includes a charge pump to convert the battery voltage to an increased voltage on the linked node. The charge pump includes capacitors and operates at a lower frequency in lower power mode and a higher frequency in higher power mode to increase power provided to the linked node.

An amplifier comprises eight transistors: the first coupled to a linked node and to a positive output node, the second coupled to the linked node and to a negative output node, the third coupled to the positive output node and a common potential, the fourth coupled to the negative output node and the common potential, the fifth coupled to a battery node, the sixth coupled to the fifth transistor and to the positive output node, the seventh coupled to the battery node, and the eighth coupled to the seventh transistor and to the negative output node. The amplifier also includes a charge pump to convert the battery voltage to an increased voltage on the linked node. The charge pump includes capacitors and operates at a lower frequency in lower power mode and a higher frequency in higher power mode to increase power provided to the linked node.