Patent US6288610B1 successfully refreshed from Google Patents.
US6288610B1
Expired / Lapsed
US
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Method and apparatus for correcting signals, apparatus for compensating for distortion, apparatus for preparing distortion compensating data, and transmitter
Assignee: Fujitsu Ltd
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Filing: 1999-06-02
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Granted: 2001-09-11
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Expires: 2019-06-02
Abstract
Abstract An apparatus for correcting signals includes a unit for estimating distortion characteristics in high-frequency circuit portion which estimates distortion characteristics of a high-frequency circuit portion concerning amplitude distortion or phase distortion impairing linearity. The apparatus further includes an input signal processor for applying an amplitude distortion correcting function or phase distortion concerning function, which is calculated on the basis of the result of estimating the distortion characteristics, to an input signal such as low-pass signals.
Inventors
- 👤 Takumi Miyashita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:42
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/32; H03F1/3241; H03F1/3282; H03F1/3288; H03F1/3223; H03F1/3247; H03F1/3252
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
196 words
An apparatus for correcting signals, comprising: a unit for estimating distortion characteristics in high-frequency circuit portion which estimates distortion characteristics of a high-frequency circuit portion concerning distortion impairing the linearity; and an input signal processing unit for applying a distortion correcting function, calculated on the basis of the result of estimating the distortion characteristics, to a given input signal, and supplying the input signal to said high-frequency circuit portion so that distortion impairing linearity, and occurring in said high-frequency circuit portion, can be corrected, wherein the input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristics; after the frequencies of the low-pass signals are raised, the low-pass signals are input to a first amplifier in said high-frequency circuit portion; after frequencies relevant to the phase distortion correction function to be applied to low-pass signals substantially identical to the low-pass signals are raised, the low-pass signals are input to a second amplifier in said high-frequency circuit portion; and output signals of said first amplifier and second amplifier are added in order to produce an output signal containing a small number of amplitude distortion components impairing linearity.
Claim 2
Independent Claim
196 words
An apparatus for correcting signals, comprising: a unit for estimating distortion characteristics in high-frequency circuit portion which estimates distortion characteristics of a high-frequency circuit portion concerning distortion impairing the linearity; and an input signal processing unit for applying a distortion correcting function, calculated on the basis of the result of estimating the distortion characteristics, to a given input signal, and supplying the input signal to said high-frequency circuit portion so that distortion impairing linearity, and occurring in said high-frequency circuit portion, can be corrected, wherein the input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristics; after the frequencies of the low-pass signals are raised, the low-pass signals are input to a first amplifier in said high-frequency circuit portion; after frequencies relevant to the phase distortion correction function to be applied to low-pass signals substantially identical to the low-pass signals are raised, the low-pass signals are input to a second amplifier in said high-frequency circuit portion; and output signals of said first amplifier and second amplifier are added in order to produce an output signal containing a small number of amplitude distortion components impairing linearity.
Claim 3
Dependent Claim
125 words
An apparatus for correcting signals according to claim 1 , wherein an envelope transfer function g(x), whose variable x indicates an input amplitude, is calculated in order to reproduce the distortion characteristics of said high-frequency circuit portion; and as the distortion correcting function, based on the envelope transfer function g(x), an amplitude distortion correcting function h(x) used to correct amplitude distortion impairing the linearity, and occurring in said high-frequency circuit portion, is determined so that the relationship of ax=g(h(x)) where a is a constant can be established, or a phase distortion correcting function p(x) used to correct phase distortion impairing the linearity, and occurring in said high-frequency circuit portion, is determined so that the relationship of c=g(p(x)) where c is a constant can be established.
Claim 4
Independent Claim
227 words
An apparatus for correcting signals, comprising: a unit for estimating distortion characteristic in high-frequency circuit portion which estimates distortion characteristics of a high-frequency circuit portion concerning at least one of amplitude distortion and phase distortion impairing linearity; and an input signal processing unit for applying at least one of an amplitude distortion correcting function and a phase distortion correcting function, which are calculated on the basis of the result of estimating the distortion characteristics, to a given input signal, and supplying the input signal to said high-frequency circuit portion so that at least one of the amplitude distortion and the phase distortion impairing the linearity, and occurring in said high-frequency circuit portion, can be corrected, wherein the input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristics; after the frequencies of the low-pass signals are raised, the low-pass signals are input to a first amplifier in said high-frequency circuit portion; after frequencies relevant to the phase distortion correction function to be applied to low-pass signals substantially identical to the low-pass signals are raised, the low-pass signals are input to a second amplifier in said high-frequency circuit portion; and output signals of said first amplifier and second amplifier are added in order to produce an output signal containing a small number of amplitude distortion components impairing linearity.
Claim 5
Independent Claim
227 words
An apparatus for correcting signals, comprising: a unit for estimating distortion characteristic in high-frequency circuit portion which estimates distortion characteristics of a high-frequency circuit portion concerning at least one of amplitude distortion and phase distortion impairing linearity; and an input signal processing unit for applying at least one of an amplitude distortion correcting function and a phase distortion correcting function, which are calculated on the basis of the result of estimating the distortion characteristics, to a given input signal, and supplying the input signal to said high-frequency circuit portion so that at least one of the amplitude distortion and the phase distortion impairing the linearity, and occurring in said high-frequency circuit portion, can be corrected, wherein the input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristics; after the frequencies of the low-pass signals are raised, the low-pass signals are input to a first amplifier in said high-frequency circuit portion; after frequencies relevant to the phase distortion correction function to be applied to low-pass signals substantially identical to the low-pass signals are raised, the low-pass signals are input to a second amplifier in said high-frequency circuit portion; and output signals of said first amplifier and second amplifier are added in order to produce an output signal containing a small number of amplitude distortion components impairing linearity.
Claim 6
Dependent Claim
122 words
An apparatus for correcting signals according to claim 3 , wherein an envelope transfer function g(x), whose variable x indicates an input amplitude, is calculated in order to reproduce the distortion characteristics of said high-frequency circuit portion; and based on the envelope transfer function g(x), an amplitude distortion correcting function h(x) used to correct the amplitude distortion impairing the linearity, and occurring in said high-frequency circuit portion, is determined so that the relationship of ax=g(h(x)) where a is a constant can be established, or a phase distortion correcting function p(x) used to correct the phase distortion impairing the linearity, and occurring in said high-frequency circuit portion, is determined so that the relationship of c=g(p(x)) where c is a constant can be established.
Claim 7
Dependent Claim
71 words
An apparatus for correcting signals according to claim 3 , wherein an approximate expression of the envelope transfer function g(x), whose variable x indicates an input amplitude, is defined as follows in order to reproduce the distortion characteristics of said high-frequency circuit portion: g(x)=a 0 +a 1 x+g′(x) where a 0 and a 1 are constants and g′(x) is a polynomial; and the amplitude distortion correcting function is defined as x*(1−g′(x)/g(x)).
Claim 8
Dependent Claim
19 words
An apparatus for correcting signals according to claim 5 , wherein the constant a 0 is set to 0.
Claim 9
Dependent Claim
53 words
An apparatus for correcting signals according to claim 5 , wherein the polynomial g′(x) in the envelope transfer function g(x)=a 0 +a 1 x+g′(x) is defined as g′(x)=Σ i=2 N a i x i where i and N are positive integers equal to or larger than 2, and a i is a constant.
Claim 10
Dependent Claim
29 words
An apparatus for correcting signals according to claim 7 , wherein only the terms of odd-numbered orders of the polynomial g′(x)=Σ i=2 N a i x i are employed.
Claim 11
Dependent Claim
21 words
An apparatus for correcting signals according to claim 3 , wherein the phase distortion correcting function p(x) is defined as p(x)=−g(x).
Claim 12
Dependent Claim
79 words
An apparatus for correcting signals according to claim 4 , wherein said input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristic, and frequencies relevant to the phase distortion correcting function p(x) to be applied to the low-pass signals are raised in order to produce an intermediate-frequency or high-frequency signal for the purpose of correcting the phase distortion impairing the linearity, and occurring in said high-frequency circuit portion.
Claim 13
Dependent Claim
49 words
An apparatus for correcting signals according to claim 4 , wherein, when frequencies relevant to the phase distortion correcting function p(x) to be applied to the input signal are raised by performing digital modulation, signals passed by transmission filters exhibiting root Nyquist characteristics are used as the input signal.
Claim 14
Dependent Claim
75 words
An apparatus for correcting signals according to claim 4 , wherein, when frequencies relevant to the phase distortion correcting function p(x) to be applied to the input signal are raised by performing quadrature modulation, a real-part signal and an imaginary-part signal constituting a complex-number signal and passed by low-pass filters, that exhibit root Nyquist characteristics and are defined on the basis of the result of estimating the distortion characteristics, are used as the input signal.
Claim 15
Dependent Claim
34 words
An apparatus for correcting signals according to claim 3 , wherein said second amplifier causes substantially no distortion, and the phase distortion impairing the linearity, and occurring in said first amplifier alone, is corrected.
Claim 16
Dependent Claim
41 words
An apparatus for correcting signals according to claim 3 , wherein the phase distortion impairing the linearity, and occurring in said first amplifier, is corrected and the phase distortion impairing the linearity, and occurring in said second amplifier, is also corrected.
Claim 17
Dependent Claim
123 words
An apparatus for correcting signals according to claim 3 , wherein the input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristics; after the frequencies of the low-pass signals are raised, the low-pass signals are input to a first amplifier in said high-frequency circuit portion; after frequencies relevant to the amplitude distortion correcting function to be applied to low-pass signals substantially identical to the low-pass signals are raised, the low-pass signals are input to a second amplifier in said high-frequency circuit portion; and output signals of said first amplifier and second amplifier are added in order to produce an output signal containing a small number of amplitude distortion components impairing the linearity.
Claim 18
Dependent Claim
33 words
An apparatus for correcting signals according to claim 15 , wherein said second amplifier causes substantially no distortion, and the amplitude distortion impairing linearity, and occurring in said first amplifier alone, is corrected.
Claim 19
Dependent Claim
41 words
An apparatus for correcting signals according to claim 15 , wherein the amplitude distortion impairing the linearity, and occurring in said first amplifier, is connected, and the amplitude distortion impairing the linearity, and occurring in said second amplifier, is also corrected.
Claim 20
Dependent Claim
96 words
An apparatus for correcting signals according to claim 3 , wherein the input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristics; an amplitude distortion correcting function to be applied to said low-pass signals is calculated; and frequencies relevant to a phase distortion correcting function in the amplitude distortion correcting function are raised in order to produce an intermediate-frequency signal or high-frequency signal for the purpose of correcting the amplitude distortion and the phase distortion impairing the linearity, and occurring in said high-frequency circuit portion.
Claim 21
Dependent Claim
78 words
An apparatus for correcting signals according to claim 4 , wherein the envelope transfer function g(x) is a function including a table function; at least one of the amplitude distortion correcting function h(x) and phase distortion correcting function p(x) is an expansion composed of a polynomial series; coefficients in the terms of orders of the expansion are calculated; and thus at least one of the amplitude distortion correcting function h(x) and phase distortion correcting function p(x) is calculated.
Claim 22
Dependent Claim
29 words
An apparatus for correcting signals according to claim 4 , wherein at least one of the amplitude distortion correcting function h(x) and phase distortion correcting function p(x) is fixed.
Claim 23
Dependent Claim
62 words
An apparatus for correcting signals according to claim 4 , wherein, when a plurality of high-frequency circuit portions are included, at least one of the amplitude distortion correcting function h(x) and phase distortion correcting function p(x), is fixed for each high-frequency circuit portion, or for each group of high-frequency circuit portions produced under the similar conditions for manufacturing a high-frequency circuit portion.
Claim 24
Dependent Claim
61 words
An apparatus for correcting signals according to claim 4 , wherein, when said high-frequency circuit portion is in operation, the envelope transfer function g(x) is calculated intermittently or all the time; and based on the result of calculating the envelope transfer function g(x), at least one of the amplitude distortion correcting function h(x) and phase distortion correcting function p(x) is modified.
Claim 25
Independent Claim
190 words
A method for correcting signals, including the steps of: estimating distortion characteristics of a high-frequency circuit portion concerning distortion impairing linearity; applying a distortion correcting function, calculated on the basis of the result of estimating the distortion characteristics, to a given input signal; and supplying the input signal to which the distortion correction function is applied, to said high-frequency circuit portion for the purpose of correcting the distortion impairing the linearity, and occurring in said high-frequency circuit portion, wherein the input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristics; after the frequencies of the low-pass signals are raised, the low-pass signals are input to a first amplifier in said high-frequency circuit portion; after frequencies relevant to the phase distortion correction function to be applied to low-pass signals substantially identical to the low-pass signals are raised, the low-pass signals are input to a second amplifier in said high-frequency circuit portion; and output signals of said first amplifier and second amplifier are added in order to produce an output signal containing a small number of amplitude distortion components impairing linearity.
Claim 26
Independent Claim
190 words
A method for correcting signals, including the steps of: estimating distortion characteristics of a high-frequency circuit portion concerning distortion impairing linearity; applying a distortion correcting function, calculated on the basis of the result of estimating the distortion characteristics, to a given input signal; and supplying the input signal to which the distortion correction function is applied, to said high-frequency circuit portion for the purpose of correcting the distortion impairing the linearity, and occurring in said high-frequency circuit portion, wherein the input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristics; after the frequencies of the low-pass signals are raised, the low-pass signals are input to a first amplifier in said high-frequency circuit portion; after frequencies relevant to the phase distortion correction function to be applied to low-pass signals substantially identical to the low-pass signals are raised, the low-pass signals are input to a second amplifier in said high-frequency circuit portion; and output signals of said first amplifier and second amplifier are added in order to produce an output signal containing a small number of amplitude distortion components impairing linearity.
Claim 27
Independent Claim
227 words
A method for correcting signals, including the steps of: estimating distortion characteristics of a high-frequency circuit portion concerning at least one of amplitude distortion and phase distortion impairing linearity; applying at least one of an amplitude distortion correcting function and phase distortion correcting function, calculated on the basis of the result of estimating the distortion characteristics, to a given input signal; and supplying the input signal to which at least one of the amplitude distortion correcting function and phase distortion correcting function is applied, to said high-frequency circuit portion for the purpose of correcting at least one of the amplitude distortion and the phase distortion impairing the linearity, and occurring in said high-frequency circuit portion, wherein the input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristics; after the frequencies of the low-pass signals are raised, the low-pass signals are input to a first amplifier in said high-frequency circuit portion; after frequencies relevant to the phase distortion correction function to be applied to low-pass signals substantially identical to the low-pass signals are raised, the low-pass signals are input to a second amplifier in said high-frequency circuit portion; and output signals of said first amplifier and second amplifier are added in order to produce an output signal containing a small number of amplitude distortion components impairing linearity.
Claim 28
Independent Claim
227 words
A method for correcting signals, including the steps of: estimating distortion characteristics of a high-frequency circuit portion concerning at least one of amplitude distortion and phase distortion impairing linearity; applying at least one of an amplitude distortion correcting function and phase distortion correcting function, calculated on the basis of the result of estimating the distortion characteristics, to a given input signal; and supplying the input signal to which at least one of the amplitude distortion correcting function and phase distortion correcting function is applied, to said high-frequency circuit portion for the purpose of correcting at least one of the amplitude distortion and the phase distortion impairing the linearity, and occurring in said high-frequency circuit portion, wherein the input signal is low-pass signals passed by low-pass filters defined on the basis of the result of estimating the distortion characteristics; after the frequencies of the low-pass signals are raised, the low-pass signals are input to a first amplifier in said high-frequency circuit portion; after frequencies relevant to the phase distortion correction function to be applied to low-pass signals substantially identical to the low-pass signals are raised, the low-pass signals are input to a second amplifier in said high-frequency circuit portion; and output signals of said first amplifier and second amplifier are added in order to produce an output signal containing a small number of amplitude distortion components impairing linearity.
Claim 29
Independent Claim
114 words
An apparatus for compensating for distortion to which an in-phase component xi and an orthogonal component xq that have been filtered by a low-pass filter, are supplied, having a function of previously distorting the in-phase component and the orthogonal component so that non-linearity of a power amplifier arranged on the downstream side can be improved, said apparatus comprising: an absolute value calculating unit for calculating an intensity of vector (xi, xq); and a predistortion unit in which a function h(x)/x obtained when a predetermined predistortion function h(x) is divided by the above intensity x is used or its reference table is used, for multiplying an output xi, xq of the low-pass filter by h(x)/x.
Claim 30
Independent Claim
114 words
An apparatus for compensating for distortion to which an in-phase component xi and an orthogonal component xq that have been filtered by a low-pass filter, are supplied, having a function of previously distorting the in-phase component and the orthogonal component so that non-linearity of a power amplifier arranged on the downstream side can be improved, said apparatus comprising: an absolute value calculating unit for calculating an intensity of vector (xi, xq); and a predistortion unit in which a function h(x)/x obtained when a predetermined predistortion function h(x) is divided by the above intensity x is used or its reference table is used, for multiplying an output xi, xq of the low-pass filter by h(x)/x.
Claim 31
Dependent Claim
49 words
An apparatus for compensating for distortion according to claim 25 , further comprising a phase pre-rotation unit in which a predetermined function or its reference table is used, and the vector (xi, xq) or the vector ((h/x)xi, (h/x)xq) generated in the above predistortion unit is rotated by angle φ(x).
Claim 32
Dependent Claim
25 words
A digital signal processor characterized in that a function of the apparatus for compensating for distortion described in claim 25 is realized by a program.
Claim 33
Dependent Claim
25 words
A digital signal processor characterized in that a function of the apparatus for compensating for distortion described in claim 26 is realized by a program.
Claim 34
Independent Claim
184 words
An apparatus preparing distortion compensation data comprising a processor ( 2 B), wherein, in order to improve nonlinearity of the power amplifier, the processor ( 2 B) is used for an apparatus for compensating for distortion in which the amplitude x of a signal on the upstream side of the power amplifier is previously distorted to the value of the predistortion function h(x); when the output amplitude with respect to the input amplitude x of the power amplifier is expressed by the function g(x), the predistortion function h(x) is made to be approximate to a power development of the amplitude x; the power development coefficients c1 to cn are given initial values; the amplitude x is made to be an amplitude of the inter-modulation wave of the base band signals, the angular frequencies of which are ω1 and ω2; and the power development coefficients c1 to cn of the predistortion function h(x) are determined so that an absolute value ε of the ratio of the primary Fourier coefficient of the function g(h(x)) with respect to the second Fourier coefficient can be substantially a minimum.
Claim 35
Independent Claim
184 words
An apparatus preparing distortion compensation data comprising a processor ( 2 B), wherein, in order to improve nonlinearity of the power amplifier, the processor ( 2 B) is used for an apparatus for compensating for distortion in which the amplitude x of a signal on the upstream side of the power amplifier is previously distorted to the value of the predistortion function h(x); when the output amplitude with respect to the input amplitude x of the power amplifier is expressed by the function g(x), the predistortion function h(x) is made to be approximate to a power development of the amplitude x; the power development coefficients c1 to cn are given initial values; the amplitude x is made to be an amplitude of the inter-modulation wave of the base band signals, the angular frequencies of which are ω1 and ω2; and the power development coefficients c1 to cn of the predistortion function h(x) are determined so that an absolute value ε of the ratio of the primary Fourier coefficient of the function g(h(x)) with respect to the second Fourier coefficient can be substantially a minimum.
Claim 36
Dependent Claim
34 words
An apparatus for preparing distortion compensation data according to claim 29 , wherein an amplitude of the intermodulation wave is determined according to the maximum value of the input amplitude of the power amplifier.
References Cited (Backward Citations)
US4882547A
Cited
US5023565A
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2004-09-10 | 2005-03-12 | 2005-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-09-10 | 2009-03-12 | 2009-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-09-10 | 2013-03-12 | 2013-09-11 | $7700.00 | Window Closed / Lapsed |