US5249203A
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US
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Phase and gain error control system for use in an i/q direct conversion receiver
Assignee: Boeing North American Inc
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Filing: 1991-02-25
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Granted: 1993-09-28
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Expires: 2011-02-25
Abstract
Abstract A system for controlling for gain and phase errors due to mismatches between signal channels in direct conversion receiver having a pair of signal channels carrying I and Q baseband component signals which are in quadrature. In accordance with the system new I' and Q' signals are generated which may be viewed as analogs of the I and Q baseband components but which are related to twice the phase angle defined by the original I and Q baseboard components signal components. Phase angles are determined based on the original I and Q baseband components signals and the new I' and Q' signals. An error signal is then formed from these signals which can be analyzed to determine the gain and phase errors affecting the I and Q baseband components. These components can then be adjusted to correct for gain and phase errors in order to compensate for hardware mismatches between the signal channels in the receiver.
Inventors
- 👤 Roger K. Loper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 05:11
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/007; H03D3/008; H03D1/00; H03D1/22; H03D1/2245; H03D2200/00; H03D2200/0001; H03D2200/0025; H03D2200/0029; H03D2200/0041; H03D2200/005; H03D7/00; H03D7/16; H03D7/165
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
225 words
A method of controlling gain and phase errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q signals which are in quadrature and are characterized by a phase angle θ A , comprising the steps of: (1) generating signals I' and Q' based on said I and Q signals by: (a) forming signals representing sin(2θ A ) and cos(2θ A ), and (b) reducing phase and gain errors included in said signals representing sin(2θ A ) and cos(2θ A ) by removing DC components included in these signals in order to produce said I' and Q' signals; (2) generating a phase angle error signal θ E based on said I, Q, I' and Q' signals by: (a) forming a first phase angle signal θ A based on said I' and Q' signals, (b) forming a second phase angle signal θ B based on said I and Q signals, and (c) forming an error signal θ E based on said first and second signals θ A and θ B ; (3) analyzing said error signal θ E as a function of said phase angle θ A to determine gain and phase errors g and p; and (4) adjusting the relationship between said I and Q signals to correct for said gain and phase errors g and p.
Claim 2
Independent Claim
225 words
A method of controlling gain and phase errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q signals which are in quadrature and are characterized by a phase angle θ A , comprising the steps of: (1) generating signals I' and Q' based on said I and Q signals by: (a) forming signals representing sin(2θ A ) and cos(2θ A ), and (b) reducing phase and gain errors included in said signals representing sin(2θ A ) and cos(2θ A ) by removing DC components included in these signals in order to produce said I' and Q' signals; (2) generating a phase angle error signal θ E based on said I, Q, I' and Q' signals by: (a) forming a first phase angle signal θ A based on said I' and Q' signals, (b) forming a second phase angle signal θ B based on said I and Q signals, and (c) forming an error signal θ E based on said first and second signals θ A and θ B ; (3) analyzing said error signal θ E as a function of said phase angle θ A to determine gain and phase errors g and p; and (4) adjusting the relationship between said I and Q signals to correct for said gain and phase errors g and p.
Claim 3
Dependent Claim
85 words
The process of claim 1, wherein: forming signals representing sin(2θ A ) and cos(2θ A ) is performed in accordance with the equations sin(2θ A )=2IQ and cos(2θ A )=I 2 -Q 2 , reducing gain and phase errors is performed by differencing said signals representing sin(2θ A ) and cos(2θ A ) with their DC components DC I and DC Q ; and forming an error signal θ E is performed by differencing said first and second signals θ A and θ B .
Claim 4
Dependent Claim
73 words
The process of claim 2, wherein: generating error reduced signals I' and Q' further includes: normalizing the amplitudes of said signals representing sin(2θ A ) and cos(2θ A ) using a signal representing the expression I 2 +Q 2 as a divisor, and reducing gain and phase errors is performed by differencing said signals representing sin(2θ A ) and cos(2θ A ) with twice their DC components 2DC I and 2DC Q .
Claim 5
Dependent Claim
32 words
The process of claim 1, wherein: forming the signal θ A is performed in accordance with the equation: ##EQU2## forming the signal θ B is performed in accordance with the equation: ##EQU3##
Claim 6
Dependent Claim
45 words
The process of claim 1, wherein: analyzing said error signal θ E as a function of phase angle is performed by evaluating θ E at θ A =0° in order to ascertain gain error and at θ A =45° in order to ascertain phase error.
Claim 7
Dependent Claim
43 words
The process of claim 1, wherein: adjusting said I and Q signals is performed in accordance with the equation: Q.sub.1 =bQ.sub.φ -aI where: Q 1 =Q signal as adjusted for errors Q.sub.φ =unadjusted Q signal a=tan p b=1/(1+g)cos p p=phase error g=gain error.
Claim 8
Dependent Claim
31 words
The process of claim 1, wherein said steps are iteratively performed with the Q input signal corresponding to values corrected in accordance with gain and phase errors ascertained in previous iterations.
Claim 9
Dependent Claim
163 words
A process for controlling gain and phase errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q baseband component signals which are in quadrature, comprising the steps of: (1) generating an error signal θ E by differencing a first phase angle signal θ B based on said I and Q signals with a second phase angle signal θ A based on I' and Q' signals approximately representing 2IQ and I 2 -Q 2 as adjusted to substantially remove their DC components in order to reduce gain and phase errors; (2) analyzing said error signal θ E as a function of phase angle in order to determine the phase error p and gain error g between the signal channels in the receiver; and (3) adjusting said I and Q signals in order to correct for gain and phase errors between said signal channels in accordance with said gain and phase error signals g and p.
Claim 10
Dependent Claim
163 words
A process for controlling gain and phase errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q baseband component signals which are in quadrature, comprising the steps of: (1) generating an error signal θ E by differencing a first phase angle signal θ B based on said I and Q signals with a second phase angle signal θ A based on I' and Q' signals approximately representing 2IQ and I 2 -Q 2 as adjusted to substantially remove their DC components in order to reduce gain and phase errors; (2) analyzing said error signal θ E as a function of phase angle in order to determine the phase error p and gain error g between the signal channels in the receiver; and (3) adjusting said I and Q signals in order to correct for gain and phase errors between said signal channels in accordance with said gain and phase error signals g and p.
Claim 11
Dependent Claim
25 words
The process of claim 8, wherein: said I' and Q' signals are normalized in accordance with a common factor in order to provide amplitude stabilization.
Claim 12
Dependent Claim
28 words
The process of claim 8, wherein: said phase angle signals θ A and θ B are formed in accordance with the expressions arctan Q'/I' and arctan Q/I, respectively.
Claim 13
Dependent Claim
67 words
The process of claim 9, wherein: said I' signal corresponds approximately to the expression 2IQ/(I 2 +Q 2 )-2DC I , and said Q' signal corresponds approximately to the expression I 2 -Q 2 /(I 2 +Q 2 )-2DC Q where: DC I =the DC component of 2IQ/(I 2 +Q 2 ) DC Q =the DC component of I 2 -Q 2 /(I 2 +Q 2 ).
Claim 14
Dependent Claim
46 words
The process of claim 8, wherein: said step of analyzing said error signal θ E includes the substeps of: (a) determining gain error g by evaluating θ E at θ A =0°, and (b) determining phase error p by evaluating θ E at θ A =45°.
Claim 15
Dependent Claim
45 words
The process of claim 8, wherein: said step of adjusting said I and Q signals is performed in accordance with the equation: Q.sub.1 =bQ.sub.φ -aI where: Q 1 =Q signal as adjusted for errors Q.sub.φ =unadjusted Q signal a=tan p b=1/(1+g)cosp p=phase error g=gain error
Claim 16
Independent Claim
157 words
An apparatus for controlling errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q baseband signals which are in quadrature, said apparatus comprising: (1) means for generating I' and Q' signals which correspond to analogs of said I and Q signals but are characterized by reduced gain and phase errors; (2) means for forming a first phase angle signal θ A based on said I' and Q' signals; (3) means for forming a second phase angle signal θ B based on said I and Q signals; (4) means for forming a phase angle error signal θ E based on said first and second phase angle signals θ A and θ B ; (5) means for analyzing said phase angle error signal θ E to determine phase error p; and (6) means for adjusting the relationship between said I and Q signals to correct for said phase error p.
Claim 17
Independent Claim
157 words
An apparatus for controlling errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q baseband signals which are in quadrature, said apparatus comprising: (1) means for generating I' and Q' signals which correspond to analogs of said I and Q signals but are characterized by reduced gain and phase errors; (2) means for forming a first phase angle signal θ A based on said I' and Q' signals; (3) means for forming a second phase angle signal θ B based on said I and Q signals; (4) means for forming a phase angle error signal θ E based on said first and second phase angle signals θ A and θ B ; (5) means for analyzing said phase angle error signal θ E to determine phase error p; and (6) means for adjusting the relationship between said I and Q signals to correct for said phase error p.
Claim 18
Dependent Claim
48 words
The apparatus of claim 14, wherein: said means for analyzing said phase angle error signal θ E is also operative for determining gain error g, and said means for adjusting the relationship between said I and Q signals is also operative for correcting for said gain error g.
Claim 19
Dependent Claim
52 words
The apparatus of claim 14, wherein: said means for generating I' and Q' signals includes: (a) means for forming signals approximately representing 2IQ and I 2 -Q 2 , (b) means for differencing said signals representing 2IQ and I 2 -Q 2 with their DC components DC I and DC Q .
Claim 20
Dependent Claim
72 words
The apparatus of claim 16, wherein: said means for generating I' and Q' signals further includes: means for normalizing said signals representing 2IQ and I 2 -Q 2 using a common divisor signal representing I 2 +Q 2 ; and wherein: said means for differencing said signals representing 2IQ and I 2 -Q 2 with their DC components differences these signals with twice their DC components 2DC I and 2DC Q .
Claim 21
Dependent Claim
38 words
The apparatus of claim 14, wherein: said means for forming a first and second phase angle signals θ A and θ B operate in accordance with the equations θ A =arctan Q'/I' and θ B =arctan Q/I, respectively.
Claim 22
Dependent Claim
49 words
The apparatus of claim 14, wherein: said means for generating I' and Q' signals is operative in accordance with the equations: I'=2IQ/(I.sup.2 +Q.sup.2)-2DC.sub.I and Q'=I.sup.2 -Q2/(I.sup.2 +Q.sup.2)-2DC.sub.Q where: DC I =DC component of 2IQ/(I 2 +Q 2 ) and DC Q =DC component of I 2 -Q2/(I 2 +Q2).
Claim 23
Dependent Claim
29 words
The apparatus of claim 14 wherein: said means for analyzing said phase error signal θ E operates to determine phase error by evaluating θ E at θ A =45.
Claim 24
Dependent Claim
33 words
The apparatus of claim 15, wherein: gain error g is determined by evaluating θ E at θ A =0°, and phase error p is determined by evaluating θ E at θ A =45°.
Claim 25
Dependent Claim
48 words
The apparatus of claim 15, wherein: said means for adjusting the relationship between said I and Q signals is operative in accordance with the equation: Q.sub.1 =bQ.sub.φ -aI where: Q 1 =Q signal as adjusted for errors Q.sub.φ =unadjusted Q signal a=tan p b=1/(1+g)cosp p=phase error g=gain error
Claim 26
Dependent Claim
54 words
The apparatus of claim 15, wherein: said means for generating I' and Q' signals is operative in accordance with the equations: I'=2IQ/(I.sup.2 +Q.sup.2)-2DC.sub.I and Q'=I.sup.2 -Q.sup.2 /(I.sup.2 +Q.sup.2)-2DC.sub.Q where: DC I =DC component of 2IQ/(I 2 +Q 2 ) and DC Q =DC component of I 2 -Q 2 /(I 2 +Q 2 )
Claim 27
Dependent Claim
117 words
A process for correcting errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q baseband signals which are in quadrature, said process comprising the steps of: (1) generating I' and Q' signals which may be viewed as analogs of said I and Q signals but which are characterized by reduced gain and phase errors; (2) forming a phase angle error signal θ E from said I and Q baseband signals and said I' and Q' signals; (3) analyzing said phase angle error signal θ E to determine phase error p; and (4) adjusting the relationship between said I and Q signals to correct for said phase error p.
Claim 28
Dependent Claim
117 words
A process for correcting errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q baseband signals which are in quadrature, said process comprising the steps of: (1) generating I' and Q' signals which may be viewed as analogs of said I and Q signals but which are characterized by reduced gain and phase errors; (2) forming a phase angle error signal θ E from said I and Q baseband signals and said I' and Q' signals; (3) analyzing said phase angle error signal θ E to determine phase error p; and (4) adjusting the relationship between said I and Q signals to correct for said phase error p.
Claim 29
Dependent Claim
114 words
The process of claim 24, wherein: said step of forming a phase angle error signal θ E includes the substeps of: (a) forming a first phase angle signal θA based on said I' and Q' signals; (b) forming a second phase angle signal θ B based on said I and Q signals; (c) forming a phase angle error signal θ E based on said first and second phase angle signals θ A and θ B ; and step of analyzing said phase angle error signal θ E is also includes determining gain error g, and said step of adjusting the relationship between said I and Q signals includes correcting for said gain error g.
Claim 30
Dependent Claim
51 words
The process of claim 24, wherein: said step of generating I' and Q' signals includes the substeps of: (a) forming signals approximately representing 2IQ and I 2 -Q 2 , (b) differencing said signals representing 2IQ and I 2 -Q 2 with their DC components DC I and DC Q .
Claim 31
Dependent Claim
77 words
The process of claim 26, wherein: said step of generating I' and Q' signals further includes the substep of: normalizing said signals representing 2IQ and I 2 -Q 2 using a signal representing I 2 +Q 2 as a common divisor; and wherein said step of differencing said signals representing 2IQ and I 2 -Q 2 with their DC components is performed by differencing these signals with twice their DC components 2DC I and 2DC Q .
Claim 32
Dependent Claim
45 words
The process of claim 24, wherein: said step of adjusting said I and Q signals is performed in accordance with the equation: Q.sub.1 =bQ.sub.φ -aI where: Q 1 =Q signal as adjusted for errors Q.sub.φ =unadjusted Q signal a=tan p b=1/(1+g)cosp p=phase error g=gain error.
References Cited (Backward Citations)
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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) | 1996-09-27 | 1997-03-29 | 1997-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-09-27 | 2001-03-29 | 2001-09-28 | $3760.00 | Window Closed / Lapsed |
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