Abstract: An amplifier comprising a main branch amplifier and an auxiliary branch amplifier, wherein one branch is a constant current-biased branch, and another branch is a voltage biased branch, with the branches connected in predetermined configurations to form a load modulated amplifier.

Abstract: A method for predistortion comprising receiving a plurality of input signals forming a multiple-input signal in a multiple-input multiple-output system, generating a pre-distorted multiple-input signal from the received multiple-input signal, generating a multiple-output signal by feeding the pre-distorted multiple-input signal into a multiple-input and multiple-output transmitter, estimating impairments generated by the multiple-input and multiple-output transmitter, the impairments comprising nonlinear crosstalk between distinct ones of the plurality of input signals; and adjusting the pre-distorted multiple-input signal to compensate for the estimated impairments.

Abstract: An artificial intelligence(AI) driven linearizerfor a transmitter, comprising an input interface for inputting linearizer signals comprising information carrying signals, and operating conditions parameter signals, other than the information carrying signal, wherein the operating conditions parameter signals represent metrics affecting transfer characteristics of the transmitter, over a selected operating range of the transmitter, and a predistortion actuator circuit configured with an AI predistortion model for predistorting at least part of the information carrying signal to produce predistorted signals, the predistortion model being configured to be operable for adaptation to said characteristics of the transmitter using a single set of model coefficients that are unchanged over said entirety of said selected operating range.

Abstract: A radio communication system for duplex communication comprising an optical carrier generator for generating optical carrier signals, a local oscillator (LO) for generating an electrical signal in a radio communication band, an information signal source, electro-optic modulators driven directly at an input electrical port by said information signal and said LO signal to modulate a portion of said optical carrier signal to form a modulated portion being an optical band information signal for transmission over an optical link; and a photodetector remote from said electro-optic modulators for receiving said transmitted optical band information signal from said optical link, and directly generating an electrical signal that is up-converted for radio transmission, or down-converted to a baseband frequency.

Abstract: A radio communication system for duplex communication comprising an optical carrier generator for generating optical carrier signals, a local oscillator (LO) for generating an electrical signal in a radio communication band, an information signal source, electro-optic modulators driven directly at an input electrical port by said information signal and said LO signal to modulate a portion of said optical carrier signal to form a modulated portion being an optical band information signal for transmission over an optical link; and a photodetector remote from said electro-optic modulators for receiving said transmitted optical band information signal from said optical link, and directly generating an electrical signal that is up-converted for radio transmission, or down-converted to a baseband frequency.

Abstract: A digital predistorter comprising a first predistorter for generating out-of-band and inter-band distortion components for compensating for the static nonlinearity of a nonlinear element, and a second predistorter cascaded with the first predistorter, the second predistorter compensating for the in-band distortion of the nonlinear device wherein the cascade of the first predistorter and the second predistorter compensate for in-band, out-of-band and inter-band distortions when the cascade of the first, the second predistorter and the nonlinear element are driven with multiband signals.

Abstract: A digital Doherty amplifier compromises a baseband signal processing block including a digital predistortion unit, a digital signal distribution unit and a digital phase alignment unit; a signal up-conversion block, an RF power amplification block, the RF power amplification block including the carrier amplifier and one or two peaking amplifiers; and a RF Doherty combining network. In another aspect, a digital Doherty amplifier compromises a baseband signal block including a digital predistortion unit, a digital signal distribution unit and an adaptive digital phase alignment unit; a signal up-conversion block; a signal up-conversion block, the signal up-conversion block including three digital-to-analog converters (DACs) and a tri-channel up-converter or three single-channel up-converters; a RF power amplification block, the RF power amplification block including the carrier amplifier and two peaking amplifiers; and an RF Doherty combining network which includes quarter wavelength impedance transformers.

Abstract: A digital predistorter comprising a first predistorter for generating out-of-band and inter-band distortion components for compensating for the static nonlinearity of a nonlinear element, and a second predistorter cascaded with the first predistorter, the second predistorter compensating for the in-band distortion of the nonlinear device wherein the cascade of the first predistorter and the second predistorter compensate for in-band, out-of-band and inter-band distortions when the cascade of the first, the second predistorter and the nonlinear element are driven with multiband signals.

Abstract: Apparatuses and methods for power amplification and signal transmission using complex delta-sigma modulation are disclosed. In one embodiment, a complex delta sigma modulator unit comprising a complex polar quantizer within an integrator loop is disclosed. The complex polar quantizer quantizes the envelope of a complex integrated signal and produces a complex quantized output signal of substantially constant envelope. The complex quantized output signal is used in deriving a complex feedback signal within the integrator loop of the complex DSM. The complex quantized output signal may be used in driving a power amplifier substantially at saturation. In some embodiments, an adjacent channel power ratio (ACPR) enhancement technique is used to reduce the quantization noise in the complex quantized output signal.

Abstract: Apparatuses and methods for power amplification and signal transmission using complex delta-sigma modulation are disclosed. In one embodiment, a complex delta sigma modulator unit comprising a complex polar quantizer within an integrator loop is disclosed. The complex polar quantizer quantizes the envelope of a complex integrated signal and produces a complex quantized output signal of substantially constant envelope. The complex quantized output signal is used in deriving a complex feedback signal within the integrator loop of the complex DSM. The complex quantized output signal may be used in driving a power amplifier substantially at saturation. In some embodiments, an adjacent channel power ratio (ACPR) enhancement technique is used to reduce the quantization noise in the complex quantized output signal.

Abstract: This specification discloses a level de-multiplexed DSM based transmitter and a method for providing the same. Broadly embodiments of the present specification enable wireless transmitters that are based on multi-level de-multiplexed DSM. A three-level de-multiplexed DSM based transmitter is disclosed as an example. More generally, the use of m-level de-multiplexed DSM is also taught, the specification thereby being enabling for broader applications to a person skilled in the art. At least one of the efficiency and linearity of transmitters can be enhanced as required for specific applications by a person of skill in the art in view of this specification and the teachings of its disclosed embodiments.

Abstract: This specification discloses a level de-multiplexed DSM based transmitter and a method for providing the same. Broadly embodiments of the present specification enable wireless transmitters that are based on multi-level de-multiplexed DSM. A three-level de-multiplexed DSM based transmitter is disclosed as an example. More generally, the use of m-level de-multiplexed DSM is also taught, the specification thereby being enabling for broader applications to a person skilled in the art. At least one of the efficiency and linearity of transmitters can be enhanced as required for specific applications by a person of skill in the art in view of this specification and the teachings of its disclosed embodiments.

Abstract: A concurrent multi-band linearized transmitter (CMLT) has a concurrent digital multi-band predistortion block (CDMPB) and a concurrent multi-band transmitter (CMT) connected to the CDMPB. The CDMPB can have a plurality of digital baseband signal predistorter blocks (DBSPBs), an analyzing and modeling (A&M) stage, and a signal observation feedback loop. Each DBSPB can have a plurality of inputs, each corresponding to a single frequency band of the multi-band input signal, and its output corresponding to a single frequency band; each output connect corresponding to an input of the CMLT. The A&M stage can have a plurality of outputs connected to and updating the parameters of the DBSPBs, and a plurality of inputs connected to either both outputs of the signal observation loop or the output of the subsampling loop and to outputs of the DBSPBs. The A&M stage can perform signals' time alignment, reconstruction of signals and compute parameters of DBSPBs.

Abstract: A concurrent multi-band linearized transmitter (CMLT) has a concurrent digital multi-band predistortion block (CDMPB) and a concurrent multi-band transmitter (CMT) connected to the CDMPB. The CDMPB can have a plurality of digital baseband signal predistorter blocks (DBSPBs), an analyzing and modeling (A&M) stage, and a signal observation feedback loop. Each DBSPB can have a plurality of inputs, each corresponding to a single frequency band of the multi-band input signal, and its output corresponding to a single frequency band; each output connect corresponding to an input of the CMLT. The A&M stage can have a plurality of outputs connected to and updating the parameters of the DBSPBs, and a plurality of inputs connected to either both outputs of the signal observation loop or the output of the subsampling loop and to outputs of the DBSPBs. The A&M stage can perform signals' time alignment, reconstruction of signals and compute parameters of DBSPBs.

Abstract: An extended bandwidth digital Doherty transmitter includes a baseband signal processing block including a digital predistortion unit. It also includes a digital signal distribution unit and a digital phase alignment unit, a signal up-conversion block, an RF power amplification block including the carrier amplifier and one or two peaking amplifiers; and an RF Doherty combining network. In another aspect, a digital Doherty transmitter includes a baseband signal block including a digital predistortion unit, a digital signal distribution unit and an adaptive digital phase alignment unit. In this aspect a signal up-conversion block includes three digital-to-analog converters (DACs) and a tri-channel up-converter or three single-channel up-converters. There is also an RF power amplification block including the carrier amplifier and two peaking amplifiers, and an RF Doherty combining network which includes quarter wavelength impedance transformers.

Abstract: Disclosed is a behavioral model for wide-band radio frequency transmitters. Also disclosed are various implementation of the behavioral model for purpose of baseband predistortion of dynamic nonlinear systems, such as wideband wireless transmitters and power amplifiers. In one example embodiment, a LBG behavioral model comprises two non-linear cascading modules: a dynamic weak nonlinear (DWNL) module, which models dynamic week nonlinearities of the system, and a static strong nonlinear (SSNL) module, which models static strong nonlinearities of the system. In one example embodiment, a forward LBG model includes DWNL module followed by the SSNL module. In another example embodiment, a reverse LBG model includes SSNL module followed by DWNL module.

Abstract: Disclosed is a behavioral model for wide-band radio frequency transmitters. Also disclosed are various implementation of the behavioral model for purpose of baseband predistortion of dynamic nonlinear systems, such as wideband wireless transmitters and power amplifiers. In one example embodiment, a LBG behavioral model comprises two non-linear cascading modules: a dynamic weak nonlinear (DWNL) module, which models dynamic week nonlinearities of the system, and a static strong nonlinear (SSNL) module, which models static strong nonlinearities of the system. In one example embodiment, a forward LBG model includes DWNL module followed by the SSNL module. In another example embodiment, a reverse LBG model includes SSNL module followed by DWNL module.

Abstract: An active predistorting linearizer with agile bypass circuit for safe mode operation is used in conjunction with an amplifier. This linearizer comprises a controllable input variable-attenuator and drive-amplifier circuit supplied with the input signal to attenuate and amplify the input signal. A predistorter includes a controllable phase-shifting and amplitude-adjusting path supplied with the attenuated and amplified input signal to distort the latter signal and produce a predistorted output signal. A controllable output variable-attenuator and drive-amplifier circuit is supplied with the predistorted output signal to attenuate and amplify this predistorted output signal before supplying it to the power amplifier. A phase-shifting and amplitude-adjusting controller is connected to the controllable input variable-attenuator and drive-amplifier circuit, the controllable phase-shifting and amplitude-adjusting path, and the controllable output variable-attenuator and drive-amplifier circuit.

Abstract: An active predistorting linearizer with agile bypass circuit for safe mode operation is used in conjunction with an amplifier. This linearizer comprises a controllable input variable-attenuator and drive-amplifier circuit supplied with the input signal to attenuate and amplify the input signal. A predistorter includes a controllable phase-shifting and amplitude-adjusting path supplied with the attenuated and amplified input signal to distort the latter signal and produce a predistorted output signal. A controllable output variable-attenuator and drive-amplifier circuit is supplied with the predistorted output signal to attenuate and amplify this predistorted output signal before supplying it to the power amplifier. A phase-shifting and amplitude-adjusting controller is connected to the controllable input variable-attenuator and drive-amplifier circuit, the controllable phase-shifting and amplitude-adjusting path, and the controllable output variable-attenuator and drive-amplifier circuit.

Abstract: A linearizer channel amplifier for use in conjunction with a power amplifier comprises an input series circuit formed of a first variable attenuator, an input drive amplifier and a power limiter, and an output series circuit formed of a second variable attenuator and an output drive amplifier. Between the input and output series circuits is interposed a linearizer. In this linearizer, a splitter produces first and second signal portions, a first path comprises serially interconnected predistorter and third variable attenuator for distorting and adjusting the amplitude of the first signal portion, a second path comprises serially interconnected phase shifter and fourth variable attenuator for phase-shifting and adjusting the amplitude of the second signal portion, and a combiner combines the distorted and amplitude-adjusted first signal portion and the phase-shifted and amplitude-adjusted second signal portion to form a predistorted output signal applied to the output series circuit.