Abstract: An advanced adaptive basedband/RF predistorting device, which advantageously uses the concept of digital receiver technology into power amplifier (PA) linearization area. The predistorting device performs an instantaneous characterization of the PA using two digital receivers to supply its AM-AM and AM-PM transfer functions.

Abstract: In a feedforward amplifier for amplifying an input signal in order to produce an amplified output signal, an error signal representative of distortion in the amplified output signal is produced and an adaptive linearization circuit is provided. In this adaptive linearization circuit, serially interconnected attenuator, phase shifter and error amplifier process the error signal to produce a feature-adjusted error signal. A coupling member combines the feature-adjusted error signal in the amplified output signal in order to cancel distortion in this amplified output signal, and a comparator/controller circuit is responsive to the error signal and the feature-adjusted error signal to control the attenuator and the phase shifter.

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.

Abstract: A feedforward amplifier system comprises a main amplifier and an auxiliary amplifier. An input signal including one carrier signal used as a first pilot signal, is supplied to a main amplifier to produce an amplified output signal. A second pilot signal is injected into the amplified output signal. The amplified output signal from the main amplifier is supplied to an output of the amplifier system through a delay line. In each of a first loop associated to the main amplifier and a second loop including the auxiliary amplifier, two control signals with pilot signal components arc produced, discrete Fourier transforms of the pilot signal components of the two control signals are calculated, and the amplitude and phase of the input signal of the main or auxiliary amplifiers are adjusted to values making the two Fourier transforms substantially equal to each other. Alternatively, the first pilot signal is produced by a generator and is injected into the input signal.