A receiver (e.g., for a 10 G 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.

A multicarrier-radio transmitter has a digital signal processor to produce a multicarrier signal at IF, and a transmit amplifier circuit to amplify and transmit the multicarrier signal at RF. A feedback loop of the transmit amplifier circuit has a subtractor, an I/Q demodulator in the forward path, a loop-filter system in the forward path at baseband, an I/Q modulator in the forward path, a power amplifier in the forward path, a pick-off node to pick off the multicarrier RF signal, and a down converter in the reverse path to down-convert the picked-off multicarrier RF signal to IF.

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 transceiver circuit and related radio frequency (RF) circuit are provided. An RF circuit is coupled to a transceiver circuit configured to generate an envelope tracking (ET) target voltage. The RF circuit includes a tracker circuit and a power amplifier circuit(s). The tracker circuit may have inherent frequency-dependent impedance that can interact with a load current of the amplifier circuit(s) to cause degradation in an ET modulated voltage, which can lead to spectral distortions in an RF offset spectrum. As such, a voltage compensation circuit is provided in the transceiver circuit and configured to add a voltage compensation term in the ET target voltage. By adding the voltage compensation term into the ET target voltage, it is possible to compensate for the degradation in the ET modulated voltage, thus helping to reduce the spectral distortions in the RF offset spectrum and improve linearity and efficiency of the amplifier circuit(s).

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.

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 transceiver circuit and related radio frequency (RF) circuit are provided. An RF circuit is coupled to a transceiver circuit configured to generate an envelope tracking (ET) target voltage. The RF circuit includes a tracker circuit and a power amplifier circuit(s). The tracker circuit may have inherent frequency-dependent impedance that can interact with a load current of the amplifier circuit(s) to cause degradation in an ET modulated voltage, which can lead to spectral distortions in an RF offset spectrum. As such, a voltage compensation circuit is provided in the transceiver circuit and configured to add a voltage compensation term in the ET target voltage. By adding the voltage compensation term into the ET target voltage, it is possible to compensate for the degradation in the ET modulated voltage, thus helping to reduce the spectral distortions in the RF offset spectrum and improve linearity and efficiency of the amplifier circuit(s).

To reduce a hardware circuit scale and a memory capacity in a communication system reducing a PAPR. A transmitter includes a transmission processing feedback type FIR filter configured to feed back data outputted from the last stage delay element of a plurality of delay elements included in an FIR filter to the first stage delay element and configured to set an initial value to a delay element in a predetermined position, of the delay elements, and performs transmission processing by using the transmission processing feedback type FIR filter. A receiver includes a reception processing feedback type FIR filter configured similarly to the transmission processing feedback type FIR filter and performs reception processing by using the reception processing feedback type FIR filter.

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.