Telefonaktiebolaget Lm Ericsson (publ)

Tony Fonden

Mats Klingberg

Richard Hellberg

Spendim Dalipi

Lars Richard Birger Hellberg

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.

Radio frequency power amplifier circuit and method

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

Method for compensating signal distortions in composite amplifiers

A method for compensating signal distortions in multiple transmitting branches () entering a composite amplifier (). According to the invention the method comprises the steps of: &#x2014;providing (S) one or more input signals (x) to the composite amplifier. &#x2014;observing (S) an output signal (z) from the composite amplifier () for each provided input signal; &#x2014;deriving (S) 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; &#x2014;deriving (S) the individual contribution from each transmitting branch () to the error by utilizing a composite amplifier model, said composite amplifier model comprising information about the contribution from each constituent amplifier () to the output signal for each provided input signal: &#x2014;compensating the signal distortions in the transmitting branches () accordingly.

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

Generation of modulated radio frequency signals

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 () for generating a first signal component, which is an estimate of a drain current of said amplifier, which means () for generating said first signal component comprises a linear filter, second means () for generating a second signal component as a function of said first signal component and at least one first gain function; third means () 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 () for combining at least said second signal component and said third signal component to form an output signal. The output signal from the predistorter is further used as input to the power amplifier, which when amplified reduces the memory effects of the amplifier.

Method and apparatus for reducing frequency memory effects in RF power amplifiers

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

Adaptation of IQ-error compensation

An adaptive predistortion arrangement includes means () for up-converting a baseband signal (S) into an intermediate frequency signal (S) having frequency aliazing and means () for down-converting a radio frequency signal (S) into an intermediate frequency signal (S) having the same frequency aliazing as the up-converted baseband signal. An adapter () adapts predistortion parameters to keep the up-converted baseband signal equal to the down-converted radio frequency signal.

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Kista, Sweden

Tony Fonden