Linearisation by signal cancellation to remove unwanted signals in a transmission

Amplifiers (or other non-linear devices) are linearised by cancelling out the unwanted distortion products. This is achieved by measuring the amplitudes and phases of these products and creating cancellation signal of equal amplitude and opposite phase. Use is made of the fast Fourier transform in b...

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Bibliographic Details
Main Author JOHN RICHARD COBDEN SNOW
Format Patent
LanguageEnglish
Published 05.09.1990
Subjects
AMPLIFIERS
BASIC ELECTRONIC CIRCUITRY
ELECTRICITY
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Summary:Amplifiers (or other non-linear devices) are linearised by cancelling out the unwanted distortion products. This is achieved by measuring the amplitudes and phases of these products and creating cancellation signal of equal amplitude and opposite phase. Use is made of the fast Fourier transform in both forward and inverse modes. The technique operates over wide bandwidths and cancellation of up to 40 dB is realised. Processing unit 1 stores an input signal in the frequency domain. After inverse Fourier transformation 2 into the time domain and conversion 3 to analogue the signal is subjected to the mono linear amplifiers. The amplifier output is redigitised 6, subjected to Fourier transformation 7; the process unit measures any unwanted frequency components (distortion) and adds a cancellation signal to the input signal prior to amplification, after which an output signal is produced.
Bibliography:Application Number: GB19890004901