A transmitter comprising a power amplifier, a phase modulator, a switched DC-DC converter, all operating in dual mode, and a controller is disclosed. The power amplifier is arranged to selectively operate either in a first mode or in a second mode, wherein the first mode is a linear mode and the second mode is a non-linear mode in order to save power with least increasing cost in hardware. The transmitter is adapted to operate at different allocated bandwidths, for different radio standards while keeping minimum power consumption governed by the controller. A transceiver, a communication device, a method and a computer program are also disclosed.

A receiver for signals. The receiver comprises, an amplifier arranged to receive and amplify the signals received by the receiver. The receiver also comprises a linearizer arranged to linearize the amplitude value of the output signals from the amplifier. In the receiver, the linearizer is arranged to perform the linearizing by means of determining actual and desired values of a statistical function for the amplitude values of the output signals from the amplifier and to replace the amplitude values of the output signals from the amplifier with amplitude values which have the same desired values of the statistical function. In embodiments of the receiver, the statistical function is the cumulative distribution function.

Embodiments of the invention provide a DPD system where the transmit reference signal is transformed, including sub-sampling, frequency translation, and the like, to match the feedback signal, which goes thru a similar transformation process, to obtain an error signal. The same transformation is applied to a system model, which may be Jacobian, Hessian, Gradient, or the like, in an adaptation algorithm to minimize error.

Methods and systems for modulating an amplifier power supply to efficiently attain amplified RF output power with much lower power dissipation than existing amplifiers. In a cable television (CATV) network, a processor receives a signal to be amplified by an amplifier at a location remote from the processor. A bias point of the amplifier may be variably modulated based on peaks of an input signal to reduce amplifier dissipation.

A radio-frequency (RF) module includes a driver transistor having a base, collector and emitter, an RF input port coupled to the base of the driver transistor, a cascode transistor having a base, collector and emitter, the emitter of the cascode transistor being coupled to the collector of the driver transistor, an RF output port coupled to the collector of the cascode transistor, and a coupling path connecting the base of the cascode transistor to the emitter of the cascode transistor, the coupling path including a capacitor.

A method for detecting an unbalance of a multi-port amplifier MPA intended to be on-board a satellite is presented. The MPA includes a plurality of paths, each path being configurable in gain and phase. The method includes transmitting a first test signal which is spread spectrum modulated from the first transmitting station to the first pathway, the first test signal being generated in at least the useful band of the first pathway; receiving by the second receiving station configured in frequency to receive signals transmitted by the second antenna connected to the second path of the MPA, the signals being likely to include a replica of the first test signal; detecting and measuring a power of received signals corresponding to a replica of the first test signal having leaked at the output of the second output port; computing at least one unbalance value of the MPA from the measurement of the power of the replica of the first test signal received in the second earth station.

Maximum likelihood bit-stream generation and detection techniques are provided using the M-algorithm and Infinite Impulse Response (IIR) filtering. The M-Algorithm is applied to a target input signal X to perform Maximum Likelihood Sequence Estimation on the target input signal X to produce a digital bit stream B, such that after filtering by an IIR filter, the produced digital stream Y produces an error signal satisfying one or more predefined requirements. The predefined requirements comprise, for example, a substantially minimum error. In an exemplary bit detection implementation, the target input signal X comprises an observed analog signal and the produced digital stream Y comprises a digitized output of a receive channel corresponding to a transmitted bit stream. In an exemplary bit stream generation implementation, the target input signal X comprises a desired transmit signal and the produced digital stream Y comprises an estimate of the desired transmit signal.

The output of a Radio Frequency (RF) Power Amplifier (PA) is sampled and down-converted, and the amplitude envelope of the baseband feedback signal is extracted. This is compared to the envelope of a transmission signal, and the envelope tracking modulation of the RF PA supply voltage is adaptively pre-distorted to achieve a constant ISO-Gain (and phase) in the RF PA. In particular, a nonlinear function is interpolated from a finite number gain values calculated from the feedback and transmission signals. This nonlinear function is then used to pre-distort the transmission signal envelope, resulting in a constant gain at the RF PA over a wide range of supply voltage values. Since the gains are calculated from a feedback signal, the pre-distortion may be recalculated at event triggers, such as an RF frequency change.

Software implementations are provided for performing IQ imbalance correction and/or RF equalization. An input signal, x, is processed in software by executing a vector convolution instruction to apply the input signal, x, to a first complex FIR filter that performs one or more of RF equalization and IQ imbalance correction; and executing a vector convolution instruction to apply a conjugate x* of the input signal, x, to a second complex FIR filter that performs the one or more of RF equalization and IQ imbalance correction, wherein the second complex FIR filter is in parallel with the first complex FIR filter. The first and second complex FIR filters have complex coefficients and the input signal comprises a complex signal.

Methods and systems for modulating an amplifier power supply to efficiently attain amplified RF output power with much lower power dissipation than existing amplifiers. In a cable television (CATV) network, a processor receives a signal to be amplified by an amplifier at a location remote from the processor. A bias point of the amplifier may be variably modulated based on peaks of an input signal to reduce amplifier dissipation.