Embodiments of this application provide a multiband power amplifier circuit and a radio frequency transceiver, to increase a VBW while ensuring linear correction and reducing a circuit loss. The multiband power amplifier circuit includes a first power transistor, a second power transistor, a first matching circuit, a second matching circuit, a third matching circuit, and a combiner. The first power transistor is coupled to a first input end of the combiner via the first matching circuit. The second power transistor is coupled to a second input end of the combiner via the second matching circuit. A first end of the third matching circuit is coupled to an output end of the first power transistor, and a second end of the third matching circuit is coupled to an output end of the second power transistor.

Disclosed is a method for producing a stage for amplifying the power of a variable envelope signal including at least one amplifier. For each amplifier, a form of ideal variation in average power POUT.sub.L is selected. For each value of each setting parameter and for each average input power value, a value of an optimisation criterion is calculated on the basis of the mathematical expectation of at least one optimisation parameter. An optimum value of each setting parameter is determined and the amplification stage is produced with a number of amplifiers in parallel determined on the basis of an average output power value and with, for each amplifier, matching circuits providing the optimum values of the setting parameters. The invention also relates to an amplification stage produced in this manner.

Disclosed is a method for producing a stage for amplifying the power of a variable envelope signal including at least one amplifier. For each amplifier, a form of ideal variation in average power POUT.sub.L is selected. For each value of each setting parameter and for each average input power value, a value of an optimisation criterion is calculated on the basis of the mathematical expectation of at least one optimisation parameter. An optimum value of each setting parameter is determined and the amplification stage is produced with a number of amplifiers in parallel determined on the basis of an average output power value and with, for each amplifier, matching circuits providing the optimum values of the setting parameters. The invention also relates to an amplification stage produced in this manner.

An audio amplifier system includes a delta-sigma modulator configured to receive an m-bit digital audio input signal and to generate a pulse density modulated signal based on the m-bit digital audio input signal. An analog power stage is coupled to the delta-sigma modulator to receive the pulse density modulated signal and amplify the pulse density modulated signal to generate an amplified pulse density modulated signal. A feedback circuit is coupled to the delta-sigma modulator and the analog power stage. The feedback circuit is configured to receive the amplified pulse density modulated signal and the pulse density modulated signal and to determine a digital error signal representative of a difference between the amplified pulse density modulated signal and the pulse density modulated signal. The feedback circuit is further configured to provide the digital error signal to the delta-sigma modulator for applying the digital error signal to a representation of the m-bit digital audio input signal.

An audio amplifier system includes a delta-sigma modulator configured to receive an m-bit digital audio input signal and to generate a pulse density modulated signal based on the m-bit digital audio input signal. An analog power stage is coupled to the delta-sigma modulator to receive the pulse density modulated signal and amplify the pulse density modulated signal to generate an amplified pulse density modulated signal. A feedback circuit is coupled to the delta-sigma modulator and the analog power stage. The feedback circuit is configured to receive the amplified pulse density modulated signal and the pulse density modulated signal and to determine a digital error signal representative of a difference between the amplified pulse density modulated signal and the pulse density modulated signal. The feedback circuit is further configured to provide the digital error signal to the delta-sigma modulator for applying the digital error signal to a representation of the m-bit digital audio input signal.

A system and method for a high-speed transmitter comprising a precoder configured to receive a sequence of input symbols and to generate for each received symbol a respective recoded symbol is disclosed. The transmitter includes a recoding unit configured for recoding each current received PAM-M based on the recoded symbol immediately preceding the current recoded symbol at the recoding unit, a shift unit configured for determining a shift value for each current received symbol from the recoding unit based on the symbol received from the recoding unit and immediately preceding the current symbol at the shift unit; and Feed-Forward Equalizer unit for applying the shift values to the respective symbols received from the recoding unit to generate a corresponding sequence of output symbols to be transmitted in an output stream.

A system and method for a high-speed transmitter comprising a precoder configured to receive a sequence of input symbols and to generate for each received symbol a respective recoded symbol is disclosed. The transmitter includes a recoding unit configured for recoding each current received PAM-M based on the recoded symbol immediately preceding the current recoded symbol at the recoding unit, a shift unit configured for determining a shift value for each current received symbol from the recoding unit based on the symbol received from the recoding unit and immediately preceding the current symbol at the shift unit; and Feed-Forward Equalizer unit for applying the shift values to the respective symbols received from the recoding unit to generate a corresponding sequence of output symbols to be transmitted in an output stream.

There is provided an electronic amplification apparatus (40) comprising a travelling wave tube amplifier (20) and a limiter (10), wherein the configuration of the amplifier (20) is optimised whilst maintaining signal linearity for operation with improved DC power efficiency at an operating point below saturation, and the limiter (10) is arranged to prevent the output power of the amplifier from going beyond a predetermined limit. This can prevent possible damage. There is also provided a multiport amplifier system (50) containing the electronic amplification apparatus (40), and a multi-feed, multi-amplifier phased array type antenna system (130) containing the electronic amplification apparatus (40), and a satellite communications system comprising the electronic amplification apparatus (40) or the multiport amplifier system (50) or the multi-feed, multi-amplifier phased array type antenna system (130).

There is provided an electronic amplification apparatus (40) comprising a travelling wave tube amplifier (20) and a limiter (10), wherein the configuration of the amplifier (20) is optimised whilst maintaining signal linearity for operation with improved DC power efficiency at an operating point below saturation, and the limiter (10) is arranged to prevent the output power of the amplifier from going beyond a predetermined limit. This can prevent possible damage. There is also provided a multiport amplifier system (50) containing the electronic amplification apparatus (40), and a multi-feed, multi-amplifier phased array type antenna system (130) containing the electronic amplification apparatus (40), and a satellite communications system comprising the electronic amplification apparatus (40) or the multiport amplifier system (50) or the multi-feed, multi-amplifier phased array type antenna system (130).

An analog amplitude pre-distortion circuit and method. The circuit includes a Radio Frequency, RF, input for receiving an RF signal. The circuit also includes an amplifier stage comprising an amplifier stage input for receiving the RF signal from the RF input, wherein the amplifier stage is operable to amplify the RF signal to produce an amplified RF signal. The circuit further includes a bias circuit. The bias circuit includes a detector stage for detecting an amplitude of the RF signal, and for producing a correction signal based on the amplitude of the RF signal. The bias circuit also includes a bias application stage coupled to the amplifier stage input.