Chopper amplifiers with low intermodulation distortion (IMD) are provided. To compensate for IMD, at least one distortion compensation channel is included in parallel with chopper amplifier circuitry of a main signal channel. Additionally, output selection switches are included for selecting between the output of the main signal path and the distortional compensation channel(s) over time to maintain the output current continuous. Such IMD compensation can be realized by filling in missing current of the main signal channel using the distortion compensation channel(s), or by using channel outputs only when they have settled current.

An amplifier circuit is disclosed. The amplifier circuit includes an input terminal configured to receive an input signal, an output terminal configured to transmit an output signal, and a first signal path including a first amplifying circuit, where the first amplifying circuit is configured to receive the input signal and to transmit a first amplified output to the output terminal, and where the first amplified output includes first amplifier circuit harmonic noise. The amplifier circuit also includes a second signal path including a second amplifying circuit, where the second amplifying circuit receives the input signal and transmits a second amplified output to the output terminal, and where the second amplified output includes second amplifier circuit harmonic noise. The output signal includes the first and second amplified outputs, and the first amplifying circuit harmonic noise is at least partially canceled by the second amplifying circuit harmonic noise in the output signal.

A multistage amplifier includes: N amplifiers (N≥2), a (k+1).sup.th amplifier cascaded to a k.sup.th amplifier (1≤k≤N−1), and each amplifier being configured to amplify a multicarrier signal; and an extraction circuit including an input and an output, the input being connected to an output of a j.sup.th amplifier (1≤j≤N−1), and the output providing a compensation signal to an input of a (j+1).sup.th amplifier or an output of the (j+1).sup.th amplifier. The extraction circuit includes a filter circuit connected to the output of the j.sup.th amplifier that extracts a distortion frequency component of n times a differential frequency f2−f1 (n≥1), a phase shifter cascaded to the filter circuit that shifts a phase of the component, and a gain adjustment circuit cascaded to the phase shifter that adjusts an amplitude of the component and generates the compensation signal.

A method of a wireless transmitter is disclosed. The method is for mitigation of distortion caused by non-linear hardware components of the transmitter, wherein mitigation of distortion comprises mitigating at least one intermodulation component, wherein the transmitter is configured to process an input signal having an input signal spectrum, and wherein the transmitter comprises two or more signal branches, each signal branch comprising a respective non-linear hardware component. The method comprises modifying the input signal for a first one of the signal branches by applying a first phase shift to a first part of the input signal spectrum, wherein the first phase shift has a first sign and a first absolute value, and applying a second phase shift to a second part of the input signal spectrum. The second phase shift has a second sign which is opposite to the first sign, and a second absolute value which is equal to the first absolute value. The first and second parts are non-overlapping. The method also comprises modifying the input signal for a second one of the signal branches by applying the first phase shift to the second part of the input signal spectrum, and applying the second phase shift to the first part of the input signal spectrum. The method further comprises feeding the modified input signals to respective ones of the signal branches. Corresponding apparatus, wireless transmitter, communication device, and computer program product are also disclosed.

Embodiments disclosed herein describe a wireless power receiver including a synchronous transistor rectifier using a Class-E or a Class-F amplifier. The wireless power receiver includes at least one radio frequency (RF) antenna configured to generate an alternating current (AC) waveform from received RF waves. The wireless power receiver further includes a power line configured to carry a first signal based on the AC current generated by the least one RF antenna, and a tap-line coupled to the power line, the tap-line being configured to carry a second signal. The second signal is based on the AC current generated by the least one RF antenna and distinct from the first signal. The wireless power receiver also includes a transistor coupled to at least the power line and the tap-line. The transistor is configured to provide a direct current (DC) waveform to a load based on the first and second signals.

The present invention provides a receiving circuit, wherein the receiving circuit includes a first ADC, an attenuator, a second ADC, a harmonic generation circuit and an output circuit. In the operations of the receiving circuit, the first ADC performs an analog-to-digital operation on an analog input signal to generate a first digital output signal, the attenuator reduces strength of the analog input signal to generate an attenuated analog input signal, the second ADC performs the analog-to-digital operation on the attenuated analog input signal to generate a second digital input signal, the harmonic generation circuit generates at least one harmonic signal according to the second digital input signal, and the output circuit deletes a harmonic component of the first digital input signal by using the at least one harmonic signal to generate an output signal.

Systems and methods are disclosed herein for selectively compensating for a specific Intermodulation Distortion (IMO) product(s) of an arbitrary order in a transmitter system. In some embodiments, a method of compensating for one or more specific IMO products in a concurrent multi-band transmitter system comprises generating an IMO correction signal for a specific IMO product as a function of two or more frequency band input signals for two or more frequency bands of a concurrent multi-band signal, the IMO product being an arbitrary order IMD product. The method further comprises frequency translating the IMD correction signal to a desired frequency that corresponds to a Radio Frequency (RF) location of the specific IMO product and, after frequency translating the IMO correction signal to the desired frequency, utilizing the IMO correction signal to compensate for the specific IMO product.

This application relates to amplifier circuitry, in particular class-D amplifiers, operable in open-loop and closed-loop modes. An amplifier (300) has a forward signal path for receiving an input signal (S.sub.IN) and outputting an output signal (S.sub.OUT) and a feedback path operable to provide a feedback signal (S.sub.FB) from the output. A feedforward path provide a feedforward signal (S.sub.FF) from the input and a combiner (105) is operable to determine an error signal (ε) based on a difference between the feedback signal and the feedforward signal. The feedforward comprises a compensation module (201) configured to apply a controlled transfer function to the feedforward signal in the closed-loop mode of operation, such that an overall transfer function for the amplifier is substantially the same in the closed-loop mode of operation and the open-loop mode of operation.

A method for determining and/or adjusting phases of at least two electrical signals is disclosed. The method includes the following steps: a first frequency and/or a first power level for a first signal is set and a second frequency and/or a second power level for a second signal is set. The first signal and the second signal are superposed, thereby obtaining a superposed signal. A power parameter of the superposed signal is determined via a power measurement unit for several different phase offsets of the first signal and/or of the second signal. A relative phase between the first signal and the second signal is determined and/or set based on the determined power parameters. Moreover, a signal generator system is disclosed.

An compensation circuit for an Amplitude Modulation-Amplitude Modulation (AM-AM) of a Radio Frequency (RF) power amplifier, including: a first biasing circuit, a power amplifier, and a compensation circuit located between the first biasing circuit and the power amplifier; herein, the compensation circuit includes a diode detection circuit and a feedforward amplifier for compensating AM-AM distortion.