A switching power amplifier includes logic circuitry that generates first and second components of a differential signal, based on received amplitude code and a delayed version of the same. The amplitude code includes a sign and a magnitude. When the sign is positive, a first logic path is configured to generate the first component based on the received amplitude code and the second logic path is configured to generate the second component based on the delayed amplitude code. When the sign is negative, the first logic path is configured to generate the first component based on the delayed amplitude code and the second logic path is configured to generate the second component based on the received amplitude code. The switching power amplifier further includes a differential-to-single ended conversion circuit configured to generate a single-ended signal based on the differential signal.

Methods and systems for optimizing amplifier operations are described. The described methods and systems particularly describe a feed-forward control circuit that may also be used as a feed-back control circuit in certain applications. The feed-forward control circuit provides a control signal that may be used to configure an amplifier in a variety of ways.

Apparatus and methods for a no-load-modulation power amplifier are described. No-load-modulation power amplifiers can comprise multiple amplifiers connected in parallel to amplify a signal that has been divided into parallel circuit branches. One of the amplifiers can operate as a main amplifier in a first amplification class and the remaining amplifiers can operate as peaking amplifiers in a second amplification class. The main amplifier can see essentially no modulation of its load between the power amplifier's fully-on and fully backed-off states. The power amplifiers can operate in symmetric and asymmetric modes. Improvements in bandwidth and drain efficiency over conventional Doherty amplifiers are obtained. Further improvements can be obtained by combining signals from the amplifiers with hybrid couplers.

An apparatus includes a first predistorter configured to calculate a first predistortion parameter and configured to distort an input signal using the first predistortion parameter to output a first distortion signal, a second predistorter configured to calculate a second predistortion parameter and configured to distort the first distortion signal using the second predistortion parameter to output a second distortion signal, a power supply configured to receive the first distortion signal to generate a first envelope signal, and configured to limit a bandwidth of the first envelope signal to obtain a second envelope signal to supply a source voltage, and a power amplifier configured to receive the source voltage and to output an output signal obtained by amplifying the second distortion signal.

A switching power amplifier includes logic circuitry that generates first and second components of a differential signal, based on received amplitude code and a delayed version of the same. The amplitude code includes a sign and a magnitude. When the sign is positive, a first logic path is configured to generate the first component based on the received amplitude code and the second logic path is configured to generate the second component based on the delayed amplitude code. When the sign is negative, the first logic path is configured to generate the first component based on the delayed amplitude code and the second logic path is configured to generate the second component based on the received amplitude code. The switching power amplifier further includes a differential-to-single ended conversion circuit configured to generate a single-ended signal based on the differential signal.

A communication circuit, including a first supply modulator configured to provide a first supply voltage; a first power amplifier configured to generate a first output signal by amplifying a first input signal corresponding to a first operation frequency band; a second power amplifier configured to generate a second output signal by amplifying a second input signal corresponding to a second operation frequency band; and a switching circuit configured to selectively provide the first supply voltage from the first supply modulator to the second power amplifier based on a first switching signal according to an operation mode.

A linear amplifier includes a pre-amplifier configured to amplify an input differential signal, a post-amplifier configured to amplify an output signal of the pre-amplifier, an amplitude detector configured to detect an amplitude of an output signal of the post-amplifier, and an output voltage corresponding to the detected amplitude, a comparator configured to control a tail current source of the pre-amplifier such that when the output voltage of the amplitude detector is less than or equal to a reference voltage, a tail current of the pre-amplifier is set to a constant value, and when the output voltage of the amplitude detector is larger than the reference voltage, the tail current is reduced to make the output voltage of the amplitude detector equal to the reference voltage.

Apparatus and methods for a no-load-modulation power amplifier are described. No-load-modulation power amplifiers can comprise multiple amplifiers connected in parallel to amplify a signal that has been divided into parallel circuit branches. One of the amplifiers can operate as a main amplifier in a first amplification class and the remaining amplifiers can operate as peaking amplifiers in a second amplification class. The main amplifier can see essentially no modulation of its load between the power amplifier's fully-on and fully backed-off states. The power amplifiers can operate in symmetric and asymmetric modes. Improvements in bandwidth and drain efficiency over conventional Doherty amplifiers are obtained. Further improvements can be obtained by combining signals from the amplifiers with hybrid couplers.

A linear amplifier includes a pre-amplifier configured to amplify an input differential signal, a post-amplifier configured to amplify an output signal of the pre-amplifier, an amplitude detector configured to detect an amplitude of an output signal of the post-amplifier, and an output voltage corresponding to the detected amplitude, a comparator configured to control a tail current source of the pre-amplifier such that when the output voltage of the amplitude detector is less than or equal to a reference voltage, a tail current of the pre-amplifier is set to a constant value, and when the output voltage of the amplitude detector is larger than the reference voltage, the tail current is reduced to make the output voltage of the amplitude detector equal to the reference voltage.

Methods and systems for optimizing amplifier operations are described. The described methods and systems particularly describe a feed-forward control circuit that may also be used as a feed-back control circuit in certain applications. The feed-forward control circuit provides a control signal that may be used to configure an amplifier in a variety of ways.