Multichannel predistortion linearizer

A method for reducing the peaking of multiple carrier modulated signals applied to the input of an amplifier and the resultant intermodulation produced at the output of the amplifier comprising the steps of:

• applying N baseband input signals to a processing means including the storing of blocks of said N baseband input signals and selectively supplying said blocks of data to said processing means for modifying the phase of selected ones of the N baseband input signals and for producing N modified signals, each modified signal corresponding to one of said N baseband input signals;
• applying each one of said N modified signals to a different one of N modulators, each modulator having a carrier signal applied to it, for modulating each carrier signal by one of said N modified signals and for producing N carrier signals modulated by said N modified signals;
• and
• combining said N carrier signals modulated by said modified signals to produce a composite signal and applying the composite signal to the input of the amplifier.

An apparatus for reducing intermodulation products resulting from the coupling of N modulated carriers to the input of an amplifier comprising:

• N input terminals, each terminal for the application thereto of a different one of N baseband input signals;
• where N is an integer greater than one;
• a signal processing means;
• means for supplying said N different baseband input signals to said signal processing means for sensing the amplitude and phase of the N baseband input signals and, in response thereto, modifying the phase of selected ones of the N baseband signals to reduce peaking resulting from the phase alignment of the input signals, and for producing N modified signals, each modified signal corresponding to one of said N baseband input signals;
• wherein said means for supplying said N different baseband input signals to said signal processing means includes memory storage elements for storing blocks of baseband input signal data and for selectively supplying said blocks of data to said signal processing means;
• means for coupling each one of the N modified signals to a different carrier modulator for producing N carrier wave signals modulated by said N modified signals and means for summing these signals and producing a composite signal;
• and
• means for applying the composite signal to the input of said amplifier for producing at its output an amplified composite signal corresponding to said N baseband input signals having a low degree of intermodulation and distortion.

A system for reducing the peaking of N carrier modulated signals applied to the input of an amplifier and the resultant intermodulation produced at the output of the amplifier, comprising:

• N input terminals, each terminal for receiving a different one of N baseband input signals;
• a signal processing means;
• an amplifier having an input and an output;
• means coupled between said N terminals and said signal processing means for supplying said N different baseband input signals to said signal processing means including memory storage elements for storing blocks of baseband input signal data and for selectively supplying said blocks of data to said signal processing means;
• said signal processing means for sensing the amplitude and phase of all the N baseband input signals and, in response thereto, producing N modified signals, each modified signal corresponding to one of said N baseband input signals with the phase of selected ones of the N baseband signals being modified to reduce peaking of the signals when they are eventually combined at the input of the amplifier;
• N carrier modulators;
• means for coupling said N modified signals to respective ones of said N carrier modulators for producing N carrier waves modulated by said N modified signals;
• and
• means coupled to said N carrier modulators for summing the N carrier waves modulated by the N modified signals and producing a composite signal applied to the input of said amplifier for producing at the output of said amplifier an amplified composite signal having less intermodulation and distortion than if the N baseband input signals had been applied without modification to their corresponding carrier modulators.