Envelope tracking systems for power amplifiers are provided herein. In certain embodiments, an envelope tracker is provided for a power amplifier that amplifies a radio frequency (RF) signal. The envelope tracker controls a power amplifier supply voltage of the power amplifier based on an envelope signal indicating an envelope of the RF signal. The envelope tracker includes a first controllable resistance between a first regulated voltage and the power amplifier supply voltage and a second controllable resistance between a second regulated voltage and the power amplifier supply voltage. The first regulated voltage and the second regulated voltage are of different voltage levels.

Envelope tracking systems for power amplifiers are provided herein. In certain embodiments, an envelope tracker is provided for a power amplifier that amplifies an RF signal. The envelope tracker includes a multi-level switching circuit having an output that provides an output current that changes in relation to an envelope signal indicating an envelope of the RF signal when the envelope tracker is operating in an envelope tracking mode. The multi-level switching circuit includes a multi-level supply (MLS) modulator that receives multiple regulated voltages of different voltage levels, and an MLS control circuit that controls the selection of the MLS modulator over time based on the envelope signal. When transitioning the MLS modulator from selection of one regulated voltage level to another regulated voltage level, the MLS control circuit provides a soft transition to gradually switch the regulated voltage levels.

A compensator system includes a control loop with a gain modifier coupled to an antenna. A control unit is configured to adjustably control the gain of a Tx signal being provided to the antenna by the gain modifier. The control unit receives feedback from a first detector connected to the output of the gain modifier that allows the first control unit to ensure the gain modifier is providing the appropriate amount of gain. A signal level can be provided to the control unit to set the desired output level from gain modifier and the signal level can be determined adjacent a transceiver that is separated from the gain modifier by a length of cable.

A method for compensating memory effects in a power amplifier comprises obtaining of an original signal. A variation of power of the original signal with time is determined. The original signal is predistorted for memory effects of the power amplifier into a predistorted signal. The predistorting comprises predistorting of the original signal in dependence of the variation of power. A power amplifier predistortion arrangement for compensating memory effects in a power amplifier, a power amplifier arrangement, and radio transmitter are also disclosed.

A power amplifier includes an output signal generator constructed to generate, on the basis of an input AC signal, an output signal including, in cycles, a first pulse being width higher in voltage than a first reference voltage and a second pulse being width lower in voltage than the first reference voltage and a feedback circuit constructed to generate a first bias signal corresponding to the output signal and feed back the first bias signal to an input side of the output signal generator to equalize a width of the first pulse and a width of the second pulse in the cycles of the output signal.

A receiver (e.g., for a 10G fiber communications link) includes an interleaved ADC coupled to a multi-channel equalizer that can provide different equalization for different ADC channels within the interleaved ADC. That is, the multi-channel equalizer can compensate for channel-dependent impairments. In one approach, the multi-channel equalizer is a feedforward equalizer (FFE) coupled to a Viterbi decorder, for example, a sliding block Viterbi decoder (SBVD); and the FFE and/or the channel estimator for the Viterbi decoder are adapted using the LMS algorithm.

Envelope tracking can be employed to reduce power consumption of a power amplifier, but envelope tracking can introduce nonlinearities to a power amplifier. These nonlinearities can manifest themselves as noise at the output of the power amplifier. Embodiments described herein provide techniques for characterizing a parameter indicative of power amplifier noise when envelope tracking is employed. Measurement of this parameter can permit power amplifier designers to decide whether to forgo envelope tracking if a power amplifier is too susceptible to such noise, redesign the power amplifier to improve compatibility with envelope tracking, or to employ distortion compensation circuitry to reduce the noise output by the power amplifier. Counterintuitively, this distortion compensation circuitry may involve increasing the power, such as the envelope tracking power supply. However, increasing the power may be a desirable trade-off for increased linearity.

A power amplification module includes an amplification circuit, a biasing circuit, a constant voltage generation circuit, a constant current generation circuit, a switching unit, and a control unit for controlling a switching operation of the switching unit, and the control unit causes the switching unit to perform switching to connect the constant voltage generation circuit to an input end of the biasing circuit when an output mode is a first output mode in which a high-frequency signal having no less than a predetermined output power is outputted from the amplification circuit, and causes the switching unit to perform switching to connect the constant current generation circuit to the input end of the biasing circuit when the output mode is a second output mode in which a power less than the predetermined output power is outputted from the amplification circuit.

A method of protecting an RF system from destructive effects of hazardous electromagnetic interference (EMI) comprises separating incoming electromagnetic radiation including hazardous electromagnetic interference according to frequency into low frequency spectral components below a selectable cutoff frequency and high frequency spectral components above the selectable cutoff frequency, and routing the low frequency portion of spectral components which include a vast majority of energy contained in the hazardous electromagnetic interference to ground via a low impedance conductor.

Apparatus and method for selective linearization of scalable fault tolerant frequency agile transmitters. In one embodiment, the method includes receiving timestamped carrier configurations and segmenting the timestamped carrier configurations into time segments having a pre-determined time length. The method also includes determining composite carrier configuration in a present time segment for a predetermined number of future time segments and determining a correction solution of a plurality of correction solutions associated with the composite carrier configuration in a mapping of a plurality of carrier configurations and the plurality of correction solutions. The method includes providing the correction solution to a linearizer of at least one of a plurality of multi-carrier power amplifiers. The plurality of power amplifiers are provided in one or more banks of multi-carrier power amplifiers.