Digital compensators for use in outphasing-based power amplification systems (e.g., Linear Amplification using Nonlinear Components (LINC) amplifiers and Asymmetric Multilevel Outphasing (AMO) amplifiers) include a short memory nonlinear portion and a long memory linear time invariant (LTI) portion. In various embodiments, compensators are provided that are of relatively low complexity and that are capable of operation at throughputs exceeding a Gigasample per second.

A phase-reconfigurable circuit for a dual-input power amplifier is provided. The circuit includes an envelope detector configured to process an envelope of an RF input signal into an envelope signal. A first vector-sum phase-shifter and a second vector-sum phase-shifter processes an in-phase and a quadrature-phase version of the RF input signal with the envelope signal to produce a first differential output signal having a dynamically-modulated phase difference with a second differential output signal.

System and method embodiments are provided for null filling of IQ waveform. In an embodiment method, samples below a predetermined threshold are selected from a plurality of samples of an input signal. Amplitude values of a complex null-fill function are then calculated to push amplitudes of the samples below the predetermined threshold to a signal level at the predetermined threshold. The phase values of the complex null-fill function are calculated to push the samples of the input signal in an IQ plane in a defined direction from a point closest to a zero signal value. The resulting complex null-fill function is filtered within a predetermined bandwidth of the input signal, and then added to the input signal to provide a modified input signal for amplification.

The present disclosure relates to digital up-conversion for a multi-band Multi-Order Power Amplifier (MOPA) that enables precise and accurate control of gain, phase, and delay of multi-band split signals input to the multi-band MOPA. In general, a multi-band MOPA is configured to amplify a multi-band signal that is split across a number, N, of inputs of the multi-band MOPA as a number, N, of multi-band split signals, where N is an order of the multi-band MOPA and is greater than or equal to 2. A digital upconversion system for the multi-band MOPA is configured to independently control a gain, phase, and delay for each of a number, M, of frequency bands of the multi-band signal for each of at least N1, and preferably all, of the multi-band split signals.

The present invention provides a compound transmitter having power efficiency characteristics and distortion characteristics superior, over a wide band, to those of a Doherty transmitter, and having fewer elements constituting an RF circuit. The present invention is therefore provided with a compound amplifier (201) for generating a signal (z) (efficiency improving signal) obtained by the amplitude modulation of a carrier signal from an RF modulation signal (a) (main signal); power-modulating, using two power amplifiers (50, 51), a signal (S1) obtained by adding together (a) and (z), and a signal (S2) obtained by subtracting (z) from (a); and setting, as a transmitter output point, the point (p1) where the respective outputs are combined via impedance inverters (60, 61), the efficiency improving signal (z) being generated under conditions in which the size of the envelope of either (S1) or (S2) is fixed.

The present disclosure is directed to a system and method for performing the outphasing technique without using a combiner at the output of two power amplifiers to reduce loss and distortions.

An amplifier circuit (100) comprises three amplifier subcircuits (121,131,141) connected via a network of transmission lines to a common node. A control circuit is configured to control the three amplifier subcircuits (121,131,141) to operate in first, second, and third operating modes, such that a first subcircuit (121) is active in the first, second, and third modes, a second sub-circuit (141) is inactive in the first mode but active in the second and third modes, and a third subcircuit (131) is inactive in the first and second modes but active in the third. A quarter-wavelength transmission line (170) couples the output node of the second sub circuit (141) to the output node (160) of the third subcircuit (131).

According to an embodiment, a digital transmitter (1) includes an amplitude modulation amplitude signal generation unit (132) that generates a function f(A(t)) of an amplitude signal A(t) as an amplitude modulation amplitude signal A(t), an amplitude modulation phase signal generation unit (133) that calculates cos.sup.1 {A(t)/f(A(t))} as a phase 1(t) and generates amplitude modulation phase signals P1(t) and P2(t), an individual digital transmission unit (11) that generates an amplified RF-pulse signal based on the signals A(t) and P1(t), an individual digital transmission unit (12) that generates an amplified RF-pulse signal based on the signals A(t) and P2(t), and an RF-synthesizer (16) that combines outputs of the individual digital transmission units (11, 12) with each other.

Methods and apparatus are provided to improve the efficiency of an outphasing amplifier through modulating the phase angle of a reflected signal in the outphasing amplifier. An outphasing amplifier includes a first amplifier and a second amplifier. A circulator is provided having a first port coupled to an output of the outphasing amplifier, a second port coupled to a load and a third port coupled to a phase shifter. The phase shifter is configured to provide a different phase angle of a reflected signal from the phase shifter to the outphasing amplifier through the circulator.

A circuit includes an amplifier configured to amplify an input signal and generate an output signal. The circuit also includes a tuning network configured to tune frequency response of the amplifier. The tuning network includes at least one tunable capacitor, where the at least one tunable capacitor includes at least one micro-electro mechanical system (MEMS) capacitor. The amplifier could include a first die, the at least one MEMS capacitor could include a second die, and the first die and the second die could be integrated in a single package. The at least one MEMS capacitor could include a MEMS superstructure disposed over a control structure, where the control structure is configured to control the MEMS superstructure and tune the capacitance of the at least one MEMS capacitor.