Distortion compensating device and distortion compensating method

Claim 2

A distortion compensating device for compensating an input-output characteristic of an amplitude and a phase of amplifying means, comprising: a distortion compensating device provided with amplitude compensating means for conversion of an in-phase signal I and an orthogonal signal Q into an in-phase signal I′=f(v i ) and an orthogonal signal Q′=f(v q ) for compensating a voltage amplitude, where v i represents a voltage of the in-phase signal and v q represents a voltage of the orthogonal signal; and means for performing the conversion by applying v i and vq to a function constituted by using two coefficients a and b and given as f(v)=−{fraction ( 1 / 2 )}·b·log((a−g·v)/(a+g·v)), the coefficients a and b being obtained as two parameters that fit the input-output characteristic of the amplifying means to a hyperbolic tangent function v out =a·tan h (b·v in ), where v in and v out represent an input voltage and output voltage respectively of the amplifying means, and g represents a linear gain.

Claim 3

A distortion compensating device comprising: amplitude compensating means for conversion of an in-phase signal I and an orthogonal signal Q into an in-phase signal I′=f(vi) and an orthogonal signal Q′=f(v q ) for compensating a voltage amplitude, where v i represents a voltage of the in-phase signal and v q represents a voltage of the orthogonal signal, the conversion being performed by applying v i and v q to a function constituted by using two coefficients a and b and given as f(v)=−½·b·log((a−g·v)/(a+g·v)), the coefficients a and b being obtained as two parameters that fit the input-output characteristic of the amplifying means to a hyperbolic tangent function v out =a·tan h (b·v in ) , where v in and v out represent an input voltage and output voltage respectively of the amplifying means, and g represents a linear gain; voltage amplitude computing means for computing a voltage amplitude v=(I′ 2 +Q′ 2 ) of the two signals I′ and Q′; a phase reference table storing a table of data uniquely corresponding to each value of the voltage amplitude v for extraction, from the table, of a specific phase value uniquely corresponding to a given voltage amplitude v; and phase synthesizing means for computing I″=I′ cos−Q′·sin and Q″=Q′·cos+I′·sin, by using the phase value and the two signals I′ and Q′, characterized in that the two signals I″ and Q″ are used as distortion compensating data.

Claim 4

A distortion compensating device comprising: amplitude compensating means for conversion of an in-phase signal I and an orthogonal signal Q into an in-phase signal I′=f(vi) and an orthogonal signal Q′=f(v q ) for compensating a voltage amplitude, where v i represents a voltage of the in-phase signal and v q represents a voltage of the orthogonal signal, the conversion being performed by applying v i and v q to a function constituted by using two coefficients a and b and given as f(v)=−½·b·log((a−g·v)/(a+g·v)), the coefficients a and b being obtained as two parameters that fit the input-output characteristic of the amplifying means to a hyperbolic tangent function v out =a·tan h (b·v in ) , where v in and v out represent an input voltage and output voltage respectively of the amplifying means, and g represents a linear gain; voltage amplitude computing means for computing a voltage amplitude v=(I′ 2 +Q′ 2 ) of the two signals I′ and Q′; a phase reference table storing a table of data uniquely corresponding to each value of the voltage amplitude v for extraction, from the table, of a specific phase value uniquely corresponding to a given voltage amplitude v; and phase synthesizing means for computing I″=I′ cos−Q′·sin and Q″=Q′·cos+I′·sin, by using the phase value and the two signals I′ and Q′, characterized in that the two signals I″ and Q″ are used as distortion compensating data.

Claim 5

The distortion compensating device according to claim 1 or claim 2 , further comprising: means for storing a plurality of phase values corresponding to a plurality of envelope voltages; means for extracting from the plurality of phase values a phase value θ corresponding to an envelope voltage of a modulated input signal; and means for changing a phase of the modulated input signal by the amount of the extracted phase value θ.

Claim 6

A distortion compensating device comprising: voltage amplitude computing means for computing a voltage amplitude v=(I 2 +Q 2 ) of two signals provided by an in-phase signal I and an orthogonal signal Q; phase difference computing means for calculating a phase difference φ between the two signals I and Q; amplitude compensating means for applying the voltage amplitude v provided by an output from the voltage amplitude computing means to a function f thereby converting into a compensating voltage amplitude f(v); I-Q restoring calculating means for calculating a signal I′=f(v)·cos φ and Q′=f(v)·sin φ, from the phase difference φ and the compensating voltage amplitude f(v); a phase reference table storing a table of phase values uniquely corresponding to each value of the voltage amplitude for extraction, from the table, of a phase value θ uniquely corresponding to a given compensating voltage amplitude f(v); and phase synthesizing means for computing I″=I′ cos θ−Q′·sin θ and Q″=Q′·cos θ+I′·sin θ, by using the phase value θ and the two signals I′ and Q′, characterized in that the two signals I″ and Q″ are used as distortion compensating data.

Claim 7

A distortion compensating device comprising: voltage amplitude computing means for computing a voltage amplitude v=(I 2 +Q 2 ) of two signals provided by an in-phase signal I and an orthogonal signal Q; phase difference computing means for calculating a phase difference φ between the two signals I and Q; amplitude compensating means for applying the voltage amplitude v provided by an output from the voltage amplitude computing means to a function f thereby converting into a compensating voltage amplitude f(v); I-Q restoring calculating means for calculating a signal I′=f(v)·cos φ and Q′=f(v)·sin φ, from the phase difference φ and the compensating voltage amplitude f(v); a phase reference table storing a table of phase values uniquely corresponding to each value of the voltage amplitude for extraction, from the table, of a phase value θ uniquely corresponding to a given compensating voltage amplitude f(v); and phase synthesizing means for computing I″=I′ cos θ−Q′·sin θ and Q″=Q′·cos θ+I′·sin θ, by using the phase value θ and the two signals I′ and Q′, characterized in that the two signals I″ and Q″ are used as distortion compensating data.

Claim 8

The distortion compensating device according to claims 1 , 2 , or 4 , wherein the calculation of the amplitude compensating value and/or the extraction of the phase value are performed by using a digital signal processor.

Claim 9

The distortion compensating device according to claims 1 , 2 , or 4 , wherein the calculation of the amplitude compensating value and/or the extraction of the phase value are performed by using a logic circuit.

Claim 10

A distortion compensating device connected before an input to a power amplifier, the device comprising: means for detecting a modulated signal thereby obtaining an envelope voltage V env of a detected envelope signal; means for fitting voltage input-output characteristics of the power amplifier to a hyperbolic function including parameters a and b, given as V out =a·tan h (b·v i ) , where v i represents an input voltage and V out represents an output voltage; means for calculating an amplitude compensating value f(V env ) by substituting the envelope voltage V env for x in a function including the parameters a and b, given as: f  ( x ) = - 1 2 · b · log   a - g · x a + g · x where g represents a linear gain of the power amplifier; means for converting an amplitude of the modulated signal based on the calculated amplitude compensating value; and means for inputting the modulated signal after the conversion to the power amplifier.

Claim 11

A distortion compensating device connected before an input to a power amplifier, the device comprising: means for detecting a modulated signal thereby obtaining an envelope voltage V env of a detected envelope signal; means for fitting voltage input-output characteristics of the power amplifier to a hyperbolic function including parameters a and b, given as V out =a·tan h (b·v i ) , where v i represents an input voltage and V out represents an output voltage; means for calculating an amplitude compensating value f(V env ) by substituting the envelope voltage V env for x in a function including the parameters a and b, given as: f  ( x ) = - 1 2 · b · log   a - g · x a + g · x where g represents a linear gain of the power amplifier; means for converting an amplitude of the modulated signal based on the calculated amplitude compensating value; and means for inputting the modulated signal after the conversion to the power amplifier.

Claim 12

The distortion compensating device according to claim 7 , wherein the calculation of the amplitude compensating value and updated parameters and/or the extraction of the phase value are performed by using a digital signal processor.

Claim 13

The distortion compensating device according to claim 7 , wherein the calculation of the amplitude compensating value and updated parameters and/or the extraction of the phase value are performed by using a logic circuit.

Claim 14

The distortion compensating device according to claim 4 or claim 7 , further comprising: means for storing a plurality of phase values corresponding to a plurality of envelope voltages; means for extracting from the plurality of phase values a phase value ⊖ corresponding to an envelope voltage of an input signal; and means for changing a phase of a modulated signal by the amount of the extracted phase value ⊖.

Claim 15

A distortion compensating device connected before an input to a power amplifier, comprising: means for detecting a modulated signal thereby obtaining a first envelope voltage of a detected envelope signal; means for fitting a voltage input-output characteristics of the power amplifier to a first function that uses predetermined parameters; means for calculating an amplitude compensating value by applying the first envelope voltage to a second function constituted by the parameters after the fitting and a linear gain of the power amplifier; means for converting an amplitude of the modulated signal based on the amplitude compensating value; means for detecting an output from the power amplifier corresponding to an input of the modulated signal after the conversion, thereby obtaining a second envelope voltage of a detected envelope signal; and means for applying the first envelope voltage and the second envelope voltage to a third function including the parameter used for the calculation of the amplitude compensating value, thereby updating the predetermined parameters, characterized in that the predetermined parameters after the updating are applied to the means for fitting.

Claim 16

A distortion compensating device connected before an input to a power amplifier, comprising: means for detecting a modulated signal thereby obtaining a first envelope voltage of a detected envelope signal; means for fitting a voltage input-output characteristics of the power amplifier to a first function that uses predetermined parameters; means for calculating an amplitude compensating value by applying the first envelope voltage to a second function constituted by the parameters after the fitting and a linear gain of the power amplifier; means for converting an amplitude of the modulated signal based on the amplitude compensating value; means for detecting an output from the power amplifier corresponding to an input of the modulated signal after the conversion, thereby obtaining a second envelope voltage of a detected envelope signal; and means for applying the first envelope voltage and the second envelope voltage to a third function including the parameter used for the calculation of the amplitude compensating value, thereby updating the predetermined parameters, characterized in that the predetermined parameters after the updating are applied to the means for fitting.

Claim 17

A distortion compensating device connected before an input to a power amplifier, comprising: means for detecting a modulated signal, thereby obtaining a first envelope voltage V env of a detected envelope signal; means for fitting voltage input-output characteristics of the power amplifier to a hyperbolic function including parameters a and b given as v out =a·tan h (b·v i ) , (where v i represents an input voltage and v out represents an output voltage); means for calculating an amplitude compensating value f(V env ) by substituting the first envelope voltage V env for x in a function including the parameters a and b, given as: f  ( x ) = - 1 2 · b · log   a - g · x a + g · x where g represents a linear gain of the power amplifier; means for converting an amplitude of the modulated signal based on the calculated amplitude compensating value; means for detecting an output from the power amplifier corresponding to an input of the modulated signal after the conversion, thereby obtaining a second envelope voltage V′ outenv of a detected envelope signal; and means for calculating updated parameters a new and b new of the parameters a and b, from a third function constituted by the parameters a and b used for the calculation of the amplitude compensating value and the envelope voltages V env and V′ outenv , given as: a new =  a - α · [ 2 · V outenv ′ · tanh  ( b · V env ) - 2 · a · tanh 2  ( b · V env ) ] b new =  b - α · [ 2 · a · V env · sech  ( b ) · -  ( a · tanh · ( b - V env ) - V outenv ′ ] where α represents a constant, characterized in that the updated parameters a new and b new are applied to the means for fitting.

Claim 18

A distortion compensating device connected before an input to a power amplifier, comprising: means for detecting a modulated signal, thereby obtaining a first envelope voltage V env of a detected envelope signal; means for fitting voltage input-output characteristics of the power amplifier to a hyperbolic function including parameters a and b given as v out =a·tan h (b·v i ) , (where v i represents an input voltage and v out represents an output voltage); means for calculating an amplitude compensating value f(V env ) by substituting the first envelope voltage V env for x in a function including the parameters a and b, given as: f  ( x ) = - 1 2 · b · log   a - g · x a + g · x where g represents a linear gain of the power amplifier; means for converting an amplitude of the modulated signal based on the calculated amplitude compensating value; means for detecting an output from the power amplifier corresponding to an input of the modulated signal after the conversion, thereby obtaining a second envelope voltage V′ outenv of a detected envelope signal; and means for calculating updated parameters a new and b new of the parameters a and b, from a third function constituted by the parameters a and b used for the calculation of the amplitude compensating value and the envelope voltages V env and V′ outenv , given as: a new =  a - α · [ 2 · V outenv ′ · tanh  ( b · V env ) - 2 · a · tanh 2  ( b · V env ) ] b new =  b - α · [ 2 · a · V env · sech  ( b ) · -  ( a · tanh · ( b - V env ) - V outenv ′ ] where α represents a constant, characterized in that the updated parameters a new and b new are applied to the means for fitting.

Claim 19

A distortion compensating method for performing a distortion compensation on a signal before being fed to a power amplifier, comprising: a step of detecting a modulated signal, thereby obtaining an envelope voltage of a detected envelope signal; a step of fitting voltage input-output characteristics of the power amplifier to a first function including a predetermined parameter, a step of calculating an amplitude compensating value by applying the envelope voltage to a second function constituted by the parameter after the step of fitting and a linear gain of the power amplifier, a step of converting an amplitude of the modulated signal based on the amplitude compensating value, and a step of inputting the modulated signal after the step of converting to the power amplifier.

Claim 20

A distortion compensating method for performing a distortion compensation on a signal before being fed to a power amplifier, comprising: a step of detecting a modulated signal, thereby obtaining an envelope voltage of a detected envelope signal; a step of fitting voltage input-output characteristics of the power amplifier to a first function including a predetermined parameter, a step of calculating an amplitude compensating value by applying the envelope voltage to a second function constituted by the parameter after the step of fitting and a linear gain of the power amplifier, a step of converting an amplitude of the modulated signal based on the amplitude compensating value, and a step of inputting the modulated signal after the step of converting to the power amplifier.

Claim 21

A distortion compensating method for performing a distortion compensation on a signal before being fed to a power amplifier, comprising: a step of detecting a modulated signal thereby obtaining an envelope voltage V env of a detected envelope signal; a step of fitting voltage input-output characteristics of the power amplifier to a hyperbolic function including parameters a and b, given as v out =a·tan h (b·v i ) , where v i represents an input voltage and v out represents an output voltage; a step of calculating an amplitude compensating value f(V env ) by substituting the envelope voltage V env for x in a function including the parameters a and b, given as: f  ( x ) = - 1 2 · b · log   a - g · x a + g · x where g represents a linear gain of the power amplifier; a step of converting an amplitude of the modulated signal based on the amplitude compensating value; and a step of for inputting the modulated signal after the step of converting to the power amplifier.

Claim 22

A distortion compensating method for performing a distortion compensation on a signal before being fed to a power amplifier, comprising: a step of detecting a modulated signal thereby obtaining an envelope voltage V env of a detected envelope signal; a step of fitting voltage input-output characteristics of the power amplifier to a hyperbolic function including parameters a and b, given as v out =a·tan h (b·v i ) , where v i represents an input voltage and v out represents an output voltage; a step of calculating an amplitude compensating value f(V env ) by substituting the envelope voltage V env for x in a function including the parameters a and b, given as: f  ( x ) = - 1 2 · b · log   a - g · x a + g · x where g represents a linear gain of the power amplifier; a step of converting an amplitude of the modulated signal based on the amplitude compensating value; and a step of for inputting the modulated signal after the step of converting to the power amplifier.