Abstract: An amplifier circuit is disclosed for providing a radio frequency output signal having a variable signal envelope, comprising a main amplifier device and an auxiliary amplifier and a combiner network for combining an output signal from said first amplifier device and a second output signal from said second amplifier device to provide a combined output signal of variable signal envelope to a load, and a signal processing circuit comprising an input and a non-linear processing section to provide at least said second radio frequency output signal with a signal envelope that has a non-linear dependency from an amplitude characteristic of the input signal such that the degree of non-linearity of the non-linear dependency varies dependent on the amount of change per time unit of the amplitude characteristic of the input signal. Further, a method of power amplifying a radio frequency signal having a variable signal envelope is disclosed.

Abstract: A method for compensating signal distortions in multiple transmitting branches entering a composite amplifier.

Abstract: An amplifier circuit is disclosed for providing a radio frequency output signal having a variable signal envelope, comprising a main amplifier device and an auxiliary amplifier and a combiner network for combining an output signal from said first amplifier device and a second output signal from said second amplifier device to provide a combined output signal of variable signal envelope to a load, and a signal processing circuit comprising an input and a non-linear processing section to provide at least said second radio frequency output signal with a signal envelope that has a non-linear dependency from an amplitude characteristic of the input signal such that the degree of non-linearity of the non-linear dependency varies dependent on the amount of change per time unit of the amplitude characteristic of the input signal. Further, a method of power amplifying a radio frequency signal having a variable signal envelope is disclosed.

Abstract: A method for compensating signal distortions in multiple transmitting branches entering a composite amplifier.

Abstract: A method for compensating signal distortions in multiple transmitting branches (3, 5; 43, 45, 46) entering a composite amplifier (1; 1?). According to the invention the method comprises the steps of: —providing (S1) one or more input signals (x) to the composite amplifier. —observing (S2) an output signal (z) from the composite amplifier (1; 1?) for each provided input signal; —deriving (S5) an error in each output signal (z) by comparing the output signal with an ideal output signal, said error being caused by said signal distortions; —deriving (S11) the individual contribution from each transmitting branch (3, 5; 43,45,46) to the error by utilizing a composite amplifier model, said composite amplifier model comprising information about the contribution from each constituent amplifier (23, 25; 103a,103b,103c) to the output signal for each provided input signal: —compensating the signal distortions in the transmitting branches (3, 5; 43,45,46) accordingly.

Abstract: The present invention relates to a method for controlling an amplifier unit having at least one drive signal input connection 1, at least one power supply voltage input connection 2 and an output connection 4. The amplifier unit comprises at least one amplifier, and the method comprises the steps of: feeding each amplifier by a drive signal from said at least one drive signal input connection 1, and feeding each amplifier by a power supply voltage from said at least one power supply voltage input connection, whereby said amplifier unit has defined output characteristics at the output connection 4 and a predetermined power supply voltage at a maximum RF output power for a RF signal. The method further comprises the steps of: operating at least one amplifier with RF output voltage characteristics to obtain a reduced shunt loss, compared to a reference shunt loss, at the output connection 4.

Abstract: RF signal generators (1) are disclosed, having an amplitude-modulated amplifier (80) whose supply voltage (70) is a signal non-linearly filtered (33) dependent on a signal (30) being representative to an envelope signal of a desired output RF signal (81). The non-linear filtering (33) is performed preferably using an envelope-dependent boundary. An input RF signal (65) to the amplifier (80) is amplified using the supply voltage (70) to produce the desired output RF signal (81). The present invention also presents methods for driving such generators (1).

Abstract: The present invention relates to a predistorter for reducing memory effects in RF power amplifiers. The invention also relates to a method for reducing memory effects in RF power amplifiers and to a base station including such a predistorter. A predistorter according to the invention includes first means (1) for generating a first signal component, which is an estimate of a drain current of said amplifier, which means (1) for generating said first signal component comprises a linear filter, second means (8) for generating a second signal component as a function of said first signal component and at least one first gain function; third means (9) for generating a third signal component as a function of a conjugate of said first signal component and at least one second gain function, and fourth means (7) for combining at least said second signal component and said third signal component to form an output signal.

Abstract: A radio transmitter with IQ-modulator error compensation includes a homodyne observation receiver (42) producing a first real baseband (S5) signal from a real radio frequency signal (S2). A real-value extracting element (44) and a down-sampler (46) convert a complex baseband signal (S1) into a second real baseband signal. An adapter (40) determines parameters controlling an IQ-error compensator (12) by minimizing the error between the two real baseband signals. In a preferred embodiment he transmitter also includes a phase shifter (56) providing three different phase shifts to compensate for the fact that the homodyne observation receiver produces a real and not a complex signal.

Abstract: The present invention relates to a method for controlling an amplifier unit having at least one drive signal input connection 1, at least one power supply voltage input connection 2 and an output connection 4. The amplifier unit comprises at least one amplifier, and the method comprises the steps of: feeding each amplifier by a drive signal from said at least one drive signal input connection 1, and feeding each amplifier by a power supply voltage from said at least one power supply voltage input connection, whereby said amplifier unit has defined output characteristics at the output connection 4 and a predetermined power supply voltage at a maximum RF output power for a RF signal. The method further comprises the steps of: operating at least one amplifier with RF output voltage characteristics to obtain a reduced shunt loss, compared to a reference shunt loss, at the output connection 4.

Abstract: The present invention relates to a predistorter for reducing memory effects in RF power amplifiers. The invention also relates to a method for reducing memory effects in RF power amplifiers and to a base station including such a predistorter. A predistorter according to the invention includes first means (1) for generating a first signal component, which is an estimate of a drain current of said amplifier, which means (1) for generating said first signal component comprises a linear filter, second means (8) for generating a second signal component as a function of said first signal component and at least one first gain function; third means (9) for generating a third signal component as a function of a conjugate of said first signal component and at least one second gain function, and fourth means (7) for combining at least said second signal component and said third signal component to form an output signal.

Abstract: An adaptive predistortion arrangement includes means (26, 40, 42, 44, 46) for up-converting a baseband signal (S1) into an intermediate frequency signal (S12) having frequency aliazing and means (18, 20, 220, 24, 26) for down-converting a radio frequency signal (S4) into an intermediate frequency signal (S7) having the same frequency aliazing as the up-converted baseband signal. An adapter (34) adapts predistortion parameters to keep the up-converted baseband signal equal to the down-converted radio frequency signal.

Abstract: A method for compensating signal distortions in multiple transmitting branches (3, 5; 43, 45, 46) entering a composite amplifier (1; 1?). According to the invention the method comprises the steps of: —providing (S1) one or more input signals (x) to the composite amplifier, —observing (S2) an output signal (z) from the composite amplifier ( 1; 1?) for each provided input signal; —deriving (S5) an error in each output signal (z) by comparing the output signal with an ideal output signal, said error being caused by said signal distortions; —deriving (S11) the individual contribution from each transmitting branch (3, 5; 43,45,46) to the error by utilising a composite amplifier model, said composite amplifier model comprising information about the contribution from each constituent amplifier (23, 25; 103a,103b,103c) to the output signal for each provided input signal: —compensating the signal distortions in the transmitting branches (3, 5; 43,45,46) accordingly.

Abstract: RF signal generators (1) are disclosed, having an amplitude-modulated amplifier (80) whose supply voltage (70) is a signal non-linearly filtered (33) dependent on a signal (30) being representative to an envelope signal of a desired output RF signal (81). The non-linear filtering (33) is performed preferably using an envelope-dependent boundary. An input RF signal (65) to the amplifier (80) is amplified using the supply voltage (70) to produce the desired output RF signal (81). The present invention also presents methods for driving such generators (1).

Abstract: A power amplifier comprises a level-discretization modulator (210) and a mixing and amplifying stage (225), in combination with a properly designed negative feedback path. The feedback path forms an error compensation loop together with a properly selected forward path. The forward path includes at least the mixing and amplifying stage (225), which provides frequency up-conversion to the radio frequency band and switch-based amplification. The negative feedback path includes a down-conversion mixer (280) for down-conversion to the initial frequency band, and compensates for distortion caused by components of the forward path.

Abstract: An adaptive predistortion arrangement includes means (26, 40, 42, 44, 46) for up-converting a baseband signal (S1) into an intermediate frequency signal (S12) having frequency aliazing and means (18, 20, 220, 24, 26) for down-converting a radio frequency signal (S4) into an intermediate frequency signal (S7) having the same frequency aliazing as the up-converted baseband signal. An adapter (34) adapts predistortion parameters to keep the up-converted baseband signal equal to the down-converted radio frequency signal.

Abstract: A radio transmitter with IQ-modulator error compensation includes a homodyne observation receiver (42) producing a first real baseband (S5) signal from a real radio frequency signal (S2). A real-value extracting element (44) and a down-sampler (46) convert a complex baseband signal (S1) into a second real baseband signal. An adapter (40) determines parameters controlling an IQ-error compensator (12) by minimizing the error between the two real baseband signals. In a preferred embodiment he transmitter also includes a phase shifter (56) providing three different phase shifts to compensate for the fact that the homodyne observation receiver produces a real and not a complex signal.

Abstract: To generate a high-power modulated radio frequency signal SOUT from an input low or medium frequency information signal SIN, the information signal is pulse-shaped in a quantifier to form a digital signal SD having discrete signal values. The digital signal is processed in a switching unit comprising switches for each signal value, in radio frequency wave generators for each switch generating carrier waves of radio frequency, and in control circuits for each switch to control the opening and closing thereof. When a switch is closed, its associated generator is connected to the output line of the switching unit, and when it is opened, the generator is disconnected therefrom. In the switching unit, a switched radio frequency signal SSW carrying the information of the input signal is formed by opening and closing the switches when the digital signal adopts or does not adopt, respectively, the signal value associated with the respective switch.

Abstract: The invention relates to a power amplifier comprising a level-discretization modulator (210) and a mixing and amplifying stage (225), in combination with a properly designed negative feedback path. The feedback path forms an error compensation loop together with a properly selected forward path. The forward path includes at least the mixing and amplifying stage (225), which provides frequency up-conversion to the radio frequency band and switch-based amplification. The negative feedback path includes a down-conversion mixer (280) for down-conversion to the initial frequency band, and compensates for distortion caused by components of the forward path. The negative feedback action will generally reduce both distortion caused by non-linear steady state impedance of the switches as well as distortion caused by non-linear steady state impedance of the switches as well as distortion resulting from switching glitches.