Predistorter
AssigneeNEC Corporation
InventorMasaki Ichihara
Life of this patent
Estimating the term…
Abstract
Disclosed is a predistorter for preliminarily compensating a distortion caused in a circuit comprising a modulator, a variable gain amplifier, and a non-linear amplifier, the predistorter comprising: an amplitude detector for detecting an amplitude of an input signal; a gain detector for detecting a gain of the variable gain amplifier; a first multiplier for multiplying the amplitude of the input signal with the gain of the variable gain to output a product therebetween; a generator for generating a predistortion function corresponding to the product; and a second multiplier for multiplying the input signal with the predistortion function to output a product therebetween to the modulator.
Claims19
A predistorter for preliminarily a compensating a distortion caused in a circuit comprising a modulator, a variable gain amplifier, and a non-linear amplifier, said predistorter comprising:
- an amplitude calculation circuit for detecting an amplitude of an input signal;
- a gain calculation circuit for detecting a gain of said variable gain amplifier;
- a first multiplier for multiplying the amplitude of the input signal with the gain of said variable gain to output a product therebetween;
- a generator for generating a predistortion function corresponding to the product;
- and a second multiplier for multiplying the input signal with the predistortion function to output a product therebetween to said modulator.
The predistorter according to claim further 3, comprising:
- a coupler for generating a shunt signal from an output of said non-linear amplifier;
- a wave detector for detecting the shunt signal to output a detected signal;
- and
- a low pass filter for filtering the detected signal to output a filtered signal;
- wherein said gain calculation circuit detects the gain of said variable gain amplifier on the basis of the filtered signal.
A method for preliminarily compensating a distortion caused in a circuit comprising a modulator, a variable gain amplifier, and a non-linear amplifier, said method comprising steps of:
- calculating an amplitude of an input signal;
- calculating a gain of said variable gain amplifier;
- multiplying the amplitude of the input signal with the gain of said variable gain to output a product therebetween;
- generating a predistortion function corresponding to the product;
- and
- input multiplying the signal with predistortion the function to output a product therebetween to said modulator.
Dependencies are inferred from the claim text.