Abstract: The present invention relates to a method for multiple-input multiple-output impairment pre-compensation comprising: receiving a multiple-input signal; 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; and adjusting the pre-distorted multiple-input signal to compensate for the estimated impairments. The present invention also relates to a pre-compensator for use with a multiple-input and multiple-output transmitter, comprising: a multiple-input for receiving a multiple-input signal; a matrix of pre-processing cells for generating a pre-distorted multiple-input signal from the received multiple-input signal; and a multiple-output for feeding the pre-distorted multiple-input signal to the multiple-input and multiple-output transmitter.

Abstract: The present disclosure is concerned with a digital transmitter using Delta-Sigma modulators (DMSs) that uses an up-sampler and modulator block that follows the DSMs to generate the RF equivalent of the baseband signal to be transmitted. The up-sampler and modulator block is simple to implement and contains only one or a few multiplexers implemented in high speed logic technology.

Abstract: An advanced adaptive baseband/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 dynamic AM-AM and AM-PM transfer functions used to synthesize Look-Up Tables (LUT) which implement the complex predistortion function in order to compensate for any non-linearity and memory effects.

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: In an adaptive method and device for predistorting a signal to be transmitted, supplied by a signal source to an input of a power amplifier having a output for delivering an amplified output signal, the following steps are conducted: predistorting the signal to be transmitted by means of cascaded predistortion amplitude and phase look-up tables interposed between the signal source and the input of the power amplifier, producing a first feedback signal in response to the predistorted signal, producing a second feedback signal in response to the amplified output signal from the power amplifier, delaying the first feedback signal for eliminating any time lag between the first and second feedback signals, and real time modeling the predistortion amplitude and phase look-up tables in response to the first and second feedback signals in order to update these two tables.

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.

Abstract: A source of microwave power is connected to the first, input, port of a six-port device whose second, output, port is connected to a device under test. A variable impedance is connected between the source and the input port. Preferably, the variable impedance is a mechanical three stub tuner. The six-port device includes a first directional coupler whose first input comprises the input port and whose first output comprises the output port. First, second and third hybrid couplers have outputs which constitute the third, fourth, fifth and sixth outputs of the six-port device. A power divider connects the directional coupler to the hybrid couplers.