Method of and apparatus for filtering intermodulation products in a radiocommunication system

Claim 1

A feed-forward multi-carrier power amplifier, comprising: a main amplifier for amplifying an input signal having a plurality of carrier frequencies and producing an amplified output signal including desired signals and unwanted frequency components; means coupled to said main amplifier for generating an error signal representative of said unwanted frequency components in the amplified output signal; synthesizer means for generating a pilot signal from a reference signal; combiner means for combining the pilot signal with the error signal to generate a phase shifter input signal; phase shifting means for varying, with respect to an input phase of the phase shifter input signal, the output phase of the phase shifter input signal and producing an error correction signal; phase detector means for generating a phase offset indication of a relative difference in phase between the pilot signal and the error correction signal; phase control processor means for comparing the phase offset indication with a phase offset value and generating a control signal; phase control means for adjusting the phase shifting means responsive to the control signal; and means for combining the error correction signal and the amplified output signal.

Claim 5

A method for controlling the amplitude and phase of unwanted signals in a multi-carrier power amplifier, comprising the steps of: a) amplifying an input signal having a plurality of carrier frequencies and producing an amplified output signal including a desired signal and unwanted frequency components; b) generating an error signal representative of said unwanted frequency components in the amplified output signal; c) generating a pilot signal from a reference signal; d) combining the pilot signal with the error signal to generate a phase shifter input signal; e) varying, with respect to an input phase, the output phase of the phase shifter input signal and producing an error correction signal; f) generating a phase offset indication of the relative difference in phase between the pilot signal and the error correction signal; g) comparing the phase offset indication with a phase offset value and generating a control signal; h) adjusting the phase shifting means responsive to the control signal; and i) combining the error correction signal and the amplified output signal.

Claim 6

A method for controlling the amplitude and phase of unwanted signals in a multi-carrier power amplifier, comprising the steps of: a) amplifying an input signal having a plurality of carrier frequencies and producing an amplified output signal including a desired signal and unwanted frequency components; b) generating an error signal representative of said unwanted frequency components in the amplified output signal; c) generating a pilot signal from a reference signal; d) combining the pilot signal with the error signal to generate a phase shifter input signal; e) varying, with respect to an input phase, the output phase of the phase shifter input signal and producing an error correction signal; f) generating a phase offset indication of the relative difference in phase between the pilot signal and the error correction signal; g) comparing the phase offset indication with a phase offset value and generating a control signal; h) adjusting the phase shifting means responsive to the control signal; and i) combining the error correction signal and the amplified output signal.

Claim 14

A method for spatially filtering unwanted signal components in a cellular radio base station having a phased array antenna, comprising the steps of: a) amplifying an input signal having a plurality of carrier frequencies and producing an amplified output signal including a desired signal and unwanted frequency components; b) generating an error signal representative of the unwanted frequency components in the amplified output signal; c) adjusting the phase of said error signal and producing an error correction signal; d) combining the error correction signal and the amplified output signal; e) radiating the combined error correction signal and the amplified output signal from a plurality of radiators which are spaced apart from each other along a line such that the plurality of radiating elements forms an array aperture; f) providing a first phase taper across the radiating elements such that the array factor for the desired signal is oriented at a first angle; and g) providing a second phase taper across the radiating elements such that the array factor for the unwanted frequency components is oriented at a second angle away from said first angle.

Claim 15

A method for spatially filtering unwanted signal components in a cellular radio base station having a phased array antenna, comprising the steps of: a) amplifying an input signal having a plurality of carrier frequencies and producing an amplified output signal including a desired signal and unwanted frequency components; b) generating an error signal representative of the unwanted frequency components in the amplified output signal; c) adjusting the phase of said error signal and producing an error correction signal; d) combining the error correction signal and the amplified output signal; e) radiating the combined error correction signal and the amplified output signal from a plurality of radiators which are spaced apart from each other along a line such that the plurality of radiating elements forms an array aperture; f) providing a first phase taper across the radiating elements such that the array factor for the desired signal is oriented at a first angle; and g) providing a second phase taper across the radiating elements such that the array factor for the unwanted frequency components is oriented at a second angle away from said first angle.