Source: http://www.google.com/patents/US7944984?dq=6106459
Timestamp: 2017-05-27 22:23:29
Document Index: 356114829

Matched Legal Cases: ['Application No. 60', 'art 11', 'art 11', 'art 11', 'art 11', 'art 11', 'art 11', 'art 11', 'art 11', 'art 11', 'art 11', 'art 16']

Patent US7944984 - I/Q calibration in the presence of phase offset - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsAn I/Q calibration system for a quadrature amplitude modulation (QAM) mode transceiver includes a signal generator that generates reference in-phase (I) and quadrature (Q) signals. An I/Q mismatch compensation module generates compensated I and Q signals based on the reference I and Q signals and amplitude...http://www.google.com/patents/US7944984?utm_source=gb-gplus-sharePatent US7944984 - I/Q calibration in the presence of phase offsetAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS7944984 B1Publication typeGrantApplication numberUS 11/705,248Publication dateMay 17, 2011Filing dateFeb 12, 2007Priority dateApr 11, 2006Fee statusPaidPublication number11705248, 705248, US 7944984 B1, US 7944984B1, US-B1-7944984, US7944984 B1, US7944984B1InventorsSongping Wu, Qing Zhao, Atul Salhotra, Hui-Ling Lou, Thomas B. ChoOriginal AssigneeMarvell International Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (15), Non-Patent Citations (14), Referenced by (17), Classifications (5), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetI/Q calibration in the presence of phase offset
US 7944984 B1Abstract
An I/Q calibration system for a quadrature amplitude modulation (QAM) mode transceiver includes a signal generator that generates reference in-phase (I) and quadrature (Q) signals. An I/Q mismatch compensation module generates compensated I and Q signals based on the reference I and Q signals and amplitude and phase correction signals. An I/Q mismatch calibration module generates the amplitude and phase correction signals. A phase stepper module varies a phase of the reference I and Q signals based on the amplitude and phase correction signals.
This application is related to U.S. patent application Ser. No. 11/503,044 filed Aug. 11, 2006, and claims the benefit of U.S. Provisional Application No. 60/790,878, filed on Apr. 11, 2006. The disclosures of the above applications are incorporated herein by reference in their entirety.
In an ideal case, the amplitudes of the unmodulated I and Q signals are equal and the I and Q signals are exactly 90° out of phase with each other. However, variances in the analog mixer pairs distort or mismatch these relationships. The mismatch is referred to as I/O mismatch. Since a receiver may incorrectly interpret the I/Q mismatch as an information signal, it is important for the transmitter to minimize the I/Q mismatch.
Operation of transceiver 10 will now be described. Transceiver 10 supports three operating modes—a receiver calibration mode, a transmitter calibration mode, and a normal operating mode. The I/O mismatch calibration process begins in the receiver calibration mode.
In the receiver calibration mode loopback switch 44 is opened, a switch 46 is closed, and the DO_CALIB and CALIB_MODE signals are set equal to “1”. Switch 46 connects the input of analog receiver 32 to a source 52. Source 52 generates a reference RF carrier that includes ideal I and Q signals. The analog mixers in analog receiver 32 introduce receiver I/Q mismatch to the ideal I and Q signals. I/Q calibrator module 48 measures the receiver I/Q mismatch and based thereon generates the correction signals. Demultiplexer 50 routes the correction signals to receive I/Q compensation module 38. I/Q compensation module 38 stores the correction signal values and thereafter compensates the received I and Q signals to eliminate the receiver I/Q mismatch.
Transceiver 10 then enters the transmitter calibration mode. In the transmitter calibration mode switch 46 is opened, loopback switch 44 is closed, the DO_CALIB signal is set equal to “1”, and the CALIB_MODE signal is set equal to “0”. Since receiver section 14 has already been compensated, I/Q calibrator module 48 can measure the transmitter I/Q mismatch and generate the correction signals for transmitter section 12. Demultiplexer 50 routes the correction signals to I/Q predistortion module 24. I/Q predistortion module 24 stores the correction signal values and thereafter compensates the I and Q signals to eliminate the transmitter I/Q mismatch. The normal operating mode can then be entered by opening loopback switch 44 and switch 46, and setting the DO_CALIB and CALIB_MODE signals equal to “0”.
An I/Q calibration system for a quadrature amplitude modulation (QAM) mode transceiver is described. The I/Q calibration system includes a signal generator that generates reference in-phase (I) and quadrature (Q) signals, an I/Q mismatch compensation module that generates compensated I and Q signals based on the reference I and Q signals and amplitude and phase correction signals, an I/Q mismatch calibration module that generates the amplitude and phase correction signals, and a phase stepper module that varies a phase of the reference I and Q signals based on the amplitude and phase correction signals.
I IF = ( S RF ) cos ( ( ω c - ω if ) t ) Eq . 5 = ( 1 + α / 2 ) I cos ( ω if t + β / 2 ) + ( 1 - α / 2 ) Q sin ( ω if t - β / 2 ) Eq . 6 The reproduced digital I signal at the output of first mixer 136-1 can be described by the equation:
I BB = ( I IF ) cos ( ω if t ) Eq . 7 = ( 1 + α / 2 ) I cos ( β / 2 ) - ( 1 - α / 2 ) Q sin ( β / 2 ) Eq . 8 The crosstalk portion at the output of second mixer 136-2 can be described by the equation:
I BB 2 - Q BB 2 = ( 1 + α / 2 ) 2 I 2 cos 2 ( β / 2 ) + ( 1 - α / 2 ) 2 Q 2 sin 2 ( β / 2 ) - 2 ( 1 - α 2 / 4 ) I Q sin β / 2 - [ ( 1 + α / 2 ) 2 I 2 sin 2 ( β / 2 ) + ( 1 - α / 2 ) 2 Q 2 cos 2 ( β / 2 ) - 2 ( 1 - α 2 / 4 ) I Q sin β / 2 ] = ( 1 + α / 2 ) 2 I 2 ( cos 2 ( β / 2 ) - sin 2 ( β / 2 ) ) - ( 1 - α / 2 ) 2 Q 2 ( cos 2 ( β / 2 ) - sin 2 ( β / 2 ) ) = [ I 2 + α I 2 + α 2 / 4 I 2 - Q 2 + α Q 2 - α 2 / 4 Q 2 ] ( cos β ) = [ ( I 2 - Q 2 ) ( 1 - α 2 / 4 ) + α ( I 2 + Q 2 ) ] cos β Noting that I = cos ( ω BB t ) and Q = sin ( ω BB t ) , ∫ 0 T ( I 2 - Q 2 ) ⅆ t = 0 , ∫ 0 T ( I 2 + Q 2 ) ⅆ t = T , ∫ 0 T I Q ⅆ t = 0. It can also be assumed that β is small. Hence cos β=1 and α<<1. Hence α2/4≈0. Thus
∫ 0 T ( I BB 2 - Q BB 2 ) ⅆ t = T α = constant × α Now considering ∫ 0 T I BB Q BB ⅆ t , I BB Q BB = ( 1 + α / 2 ) 2 I 2 sin β / 2 + ( 1 - α / 2 ) 2 Q 2 sin β / 2 - ( 1 - α 2 / 4 ) I / Q ( cos 2 ( β / 2 ) + sin 2 ( β / 2 ) ) = sin β / 2 [ I 2 + αI 2 α 2 I 2 / 4 + Q 2 - αQ 2 α 2 Q 2 / 4 ] - ( 1 - α 2 / 4 ) I / Q Eq . 10 From the above assumption that β is small,
∫ 0 T I BB Q BB ⅆ t = T β = constant × β . Eq . 11 I/Q-MCM 106 can therefore employ Eq. 10 and Eq. 11 to estimate the amplitude mismatch α and the phase mismatch β respectively and generate corresponding correction signals 105.
Referring now to FIG. 7, a gain plot 340 and a phase plot 350 show respective ones of amplitude correction signal αest 105-1 and phase correction signal βest 105-2 as the method of FIG. 6 executes. The plots are generated with a signal-to-noise ratio (SNR) of 30 dB, an I/Q phase mismatch of 2°, an I/Q gain mismatch of 3%, and no phase offset φ between analog transmit mixer module 114 and receive mixer module 122. The horizontal axis represents iteration numbers of the amplitude and phase mismatch estimates. Gain plot 340 and phase plot 350 show that the amplitude and phase estimates converge within about 100 iterations when there is no phase offset φ between analog transmit mixer module 114 and receive mixer module 122. As the phase offset φ increases it can take more iterations for the amplitude and phase mismatch estimates to converge. In some cases, such as when the phase offset φ is a multiple of 45 degrees, the amplitude and phase mismatch estimates can diverge.
Referring now to FIG. 8, a gain plot 420 and a phase plot 430 show respective ones of amplitude correction signal αest 105-1 and phase correction signal βest 105-2 as the method of FIG. 6 executes. The plots are generated with a signal-to-noise ratio (SNR) of 30 dB, an I/Q phase mismatch of 2°, an I/Q gain mismatch of 3%, and phase offset φ=45°. The horizontal axis represents iteration numbers of the amplitude, and phase mismatch estimates. Gain plot 420 and phase plot 430 show that the amplitude and phase estimates do not converge when phase offset φ is equal to 45 degrees.
Referring now to FIG. 9, a gain plot 440 and a phase plot 450 show respective ones of amplitude correction signal αest 105-1 and phase correction signal βest 105-2 as the method of FIG. 6 executes. The plots are generated with a signal-to-noise ratio (SNR) of 30 dB, an I/Q phase mismatch of 2°, an I/Q gain mismatch of 3%, and phase offset φ=90°. The horizontal axis represents iteration numbers of the amplitude and phase mismatch estimates. Gain plot 420 and phase plot 430 show that the amplitude and phase estimates do not converge when phase offset φ is equal to 90 degrees.
s ( t ) = ( 1 + α 2 ) I cos ( ω c t + β 2 ) - ( 1 - α 2 ) Q sin ( ω c t - β 2 ) . Eq . 12 The received signals at the outputs of receive mixer module 122 can be represented by the equations
I rx m =I rx cos(φ)+Q rx sin(φ) Eq. 13
Q rx m =Q rx cos(φ)−I rx sin(φ), Eq. 14
I/Q-MCM 106 adaptively estimates values of amplitude mismatch αn and the phase mismatch βn based on the equations
α n = α n - 1 + ∑ i = 0 L - 1 ( ( I rx m ) 2 - ( Q rx m ) 2 ) = α n - 1 + cos ( 2 ϕ ) ∑ i = 0 L - 1 ( I rx 2 - Q rx 2 ) + 2 sin ( 2 ϕ ) ∑ i = 0 L - 1 ( I rx · Q rx ) and Eq . 15 β n = β n - 1 + ∑ i = 0 L - 1 ( I rx m · Q rx m ) = β n - 1 + cos ( 2 ϕ ) ∑ i = 0 L - 1 ( I rx · Q rx ) - sin ( 2 ϕ ) 2 ∑ i = 0 L - 1 ( I rx 2 - Q rx 2 ) , Eq . 16. where the single-tone signal from reference signal generator 103 includes L samples in the digital domain and a period Ts. Eqs. 15 and 16 show that the phase offset φ affects the amplitude mismatch estimates αn and the phase mismatch estimates βn. A method that is described below employs phase stepper module 402 to eliminate the effects of phase offset φ on the amplitude mismatch estimates αn and the phase mismatch estimates βn.
Referring now to FIG. 12, a gain plot 540 and a phase plot 560 show respective ones of amplitude correction signal αest 105-1 and phase correction signal βest 105-2 as method 500 executes. A phase-offset plot 580 shows the corresponding output of phase stepper module 402. The plots are generated with a signal-to-noise ratio (SNR) of 30 dB, an I/Q phase mismatch of 2°, an I/Q gain mismatch of 3%, and phase offset φ=45°. The horizontal axis represents iterations of the amplitude and phase mismatch estimates.
Referring now to FIG. 13, a gain plot 600 and a phase plot 620 show respective ones of amplitude correction signal αest 105-1 and phase correction signal βest 105-2 as method 500 executes. A phase-offset plot 640 shows the corresponding output of phase stepper module 402. The plots are generated with a signal-to-noise ratio (SNR) of 30 dB, an I/Q phase mismatch of 2°, an I/Q gain mismatch of 3%, and phase offset φ=90°. The horizontal axis represents iteration numbers of the amplitude and phase mismatch estimates.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS5371481 *Mar 24, 1993Dec 6, 1994Nokia Mobile Phones Ltd.Tuning techniques for I/Q channel signals in microwave digital transmission systemsUS5903823 *Mar 18, 1996May 11, 1999Fujitsu LimitedRadio apparatus with distortion compensating functionUS6044112 *Jul 3, 1997Mar 28, 2000Hitachi America, Ltd.Methods and apparatus for correcting amplitude and phase imbalances in demodulatorsUS6340883 *Aug 31, 1999Jan 22, 2002Sony/Tektronik CorporationWide band IQ splitting apparatus and calibration method therefor with balanced amplitude and phase between I and QUS6763227 *Nov 7, 2001Jul 13, 2004Texas Instruments IncorporatedSystems and methods for modulator calibrationUS7346122 *Aug 20, 2003Mar 18, 2008Weixun CaoDirect modulation of a power amplifier with adaptive digital predistortionUS7382297 *Aug 11, 2006Jun 3, 2008Marvell International Ltd.Transmitter I/Q mismatch calibration for low IF design systemsUS7480348 *Aug 17, 2004Jan 20, 2009Sharp Kabushiki KaishaI/Q demodulation circuitUS7647026 *Feb 16, 2006Jan 12, 2010Broadcom CorporationReceiver architecture for wireless transceiverUS20030174783 *Mar 12, 2002Sep 18, 2003Mahibur RahmanSelf calibrating transmit path correction systemUS20030231723 *Jun 18, 2002Dec 18, 2003Broadcom CorporationDigital estimation and correction of I/Q mismatch in direct conversion receiversUS20040146120 *Jan 24, 2003Jul 29, 2004Brown James E. C.Receiver having automatic burst mode I/Q gain and phase balanceUS20050075815 *Sep 19, 2003Apr 7, 2005Webster Mark A.On-signal quadrature modulator calibrationUS20050148304 *Dec 24, 2003Jul 7, 2005Fodus Communications, Inc.Calibration method for the correction of in-phase quadrature signal mismatch in a radio frequency transceiverUS20050152463 *Feb 18, 2003Jul 14, 2005Paul DechampsI/q mismatch compensation in an ofdm receiver in presence of frequency offset* Cited by examinerNon-Patent CitationsReference1802.11n; IEEE P802.11-04/0889r6; Wireless LANs, TGn Sync Proposal Technical Specification; May 2005; 131 pages.2ANSI/IEEE Std 802.11, 1999 Edition; Information technology-Telecommunications and information exchange between-Local and metropolitan area networks-Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications; LAN/MAN Standards Committee of the IEEE Computer Society; 528 pages.3ANSI/IEEE Std 802.11, 1999 Edition; Information technology—Telecommunications and information exchange between—Local and metropolitan area networks—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications; LAN/MAN Standards Committee of the IEEE Computer Society; 528 pages.4IEEE 802.20-PD-06, IEEE P 802.20 V14, Jul. 16, 2004, Draft 802.20 Permanent Document, System Requirements for IEEE 802.20 Mobile Broadband Wireless Access Systems-Version 14, 23 pages.5IEEE 802.20-PD-06, IEEE P 802.20 V14, Jul. 16, 2004, Draft 802.20 Permanent Document, System Requirements for IEEE 802.20 Mobile Broadband Wireless Access Systems—Version 14, 23 pages.6IEEE P802.11g/D8.2, Apr. 2003 (Supplement to ANSI/IEEE Std 802.11-1999(Reaff 2003)); Draft Supplement to Standard [for] Information Technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Further Higher Data Rate Extension in the 2.4 GHz Band; LAN/MAN Standards Committee of the IEEE Computer Society; 69 pages.7IEEE P802.11g/D8.2, Apr. 2003 (Supplement to ANSI/IEEE Std 802.11-1999(Reaff 2003)); Draft Supplement to Standard [for] Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Further Higher Data Rate Extension in the 2.4 GHz Band; LAN/MAN Standards Committee of the IEEE Computer Society; 69 pages.8IEEE Std 802.11a-1999 (Supplement to IEEE Std 802.11-1999) [Adopted by ISO/IEC and redesignated as ISO/IEC 8802-11: 1999/Amd 1:2000(E)]; Supplement to IEEE Standard for Information technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications High-speed Physical Layer in the 5 GHz Band; LAN/MAN Standards Committee of the IEEE Computer Society; 91 pages.9IEEE Std 802.11a-1999 (Supplement to IEEE Std 802.11-1999) [Adopted by ISO/IEC and redesignated as ISO/IEC 8802-11: 1999/Amd 1:2000(E)]; Supplement to IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications High-speed Physical Layer in the 5 GHz Band; LAN/MAN Standards Committee of the IEEE Computer Society; 91 pages.10IEEE Std 802.11b-1999 (Supplement to IEEE Std 802.11-1999 Edition); Supplement to IEEE Standard for Information technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specificiations: Higher-Speed Physical Layer Extension in the 2.4 GHz Band; LAN/MAN Standards Committee of the IEEE Computer Society; Sep. 16, 1999 IEEE-SA Standards Board; 96 pages.11IEEE Std 802.11b-1999 (Supplement to IEEE Std 802.11-1999 Edition); Supplement to IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specificiations: Higher-Speed Physical Layer Extension in the 2.4 GHz Band; LAN/MAN Standards Committee of the IEEE Computer Society; Sep. 16, 1999 IEEE-SA Standards Board; 96 pages.12IEEE Std 802.11h-2003 (Amendment to IEEE Std 802.11, 1999 Edition (Reaff 2003)); as amended by IEEE Stds 802.11a-1999, 802.11b-1999, 802.11b-1999/Cor 1-2001, 802.11d-2001, and 802.11g-2003; IEEE Standard for Information technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications Amendment 5: Spectrum and Transmit Power Management Extensions in the 5 GHz band in Europe; IEEE Computer Society LAN/MAN Standards Committee; Oct. 14, 2003; 74 pages.13IEEE Std 802.11h—2003 (Amendment to IEEE Std 802.11, 1999 Edition (Reaff 2003)); as amended by IEEE Stds 802.11a-1999, 802.11b-1999, 802.11b-1999/Cor 1-2001, 802.11d-2001, and 802.11g-2003; IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications Amendment 5: Spectrum and Transmit Power Management Extensions in the 5 GHz band in Europe; IEEE Computer Society LAN/MAN Standards Committee; Oct. 14, 2003; 74 pages.14IEEE Std 802.16-2004 (revision of IEEE Std 802.16-2001) IEE Standard for Local and metropolitan area networks; Part 16: Air Interface for Fixed Broadband Wireless Access Systems; IEEE Computer Society and the IEEE Microwave Theory and Techniquest Society; Oct. 1, 2004; 893 pages.Referenced byCiting PatentFiling datePublication dateApplicantTitleUS8184740 *Mar 6, 2007May 22, 2012Nec CorporationSignal processing circuitUS8311083 *Dec 29, 2009Nov 13, 2012Texas Instruments IncorporatedJoint transmit and receive I/Q imbalance compensationUS8670738 *Sep 19, 2011Mar 11, 2014Mediatek Inc.Imbalance compensator for correcting mismatch between in-phase branch and quadrature branch, and related imbalance compensation method and direct conversion receiving apparatus thereofUS9036753 *Nov 17, 2014May 19, 2015Realtek Semiconductor Corp.Calibration method and calibration apparatus for calibrating mismatch between I-path and Q-path of transmitter/receiverUS9130626Mar 26, 2014Sep 8, 2015Qualcomm IncorporatedFrequency dependent I/Q impairment compensationUS9166707 *Mar 28, 2013Oct 20, 2015Panasonic CorporationTransmitter, signal generation device, calibration method, and signal generation methodUS9300444 *Jul 25, 2013Mar 29, 2016Analog Devices, Inc.Wideband quadrature error correctionUS9362942 *Jun 15, 2015Jun 7, 2016Maxim Integrated Products, Inc.System characteristic identification systems and methodsUS20100239056 *Mar 6, 2007Sep 23, 2010Nec CorporationSignal processing circuitUS20110158297 *Dec 29, 2009Jun 30, 2011Texas Instruments IncorporatedJoint transmit and receive i/q imbalance compensationUS20130069738 *Sep 19, 2011Mar 21, 2013Yih-Ming TsuieImbalance compensator for correcting mismatch between in-phase branch and quadrature branch, and related imbalance compensation method and direct conversion receiving apparatus thereofUS20140155006 *Mar 28, 2013Jun 5, 2014Panasonic CorporationTransmitter, signal generation device, calibration method, and signal generation methodUS20150030102 *Jul 25, 2013Jan 29, 2015Analog Devices, Inc.Wideband quadrature error correctionUS20150030103 *Jul 24, 2014Jan 29, 2015Analog Devices, Inc.Wideband quadrature error detection and correctionUS20160302159 *Apr 10, 2015Oct 13, 2016Qualcomm IncorporatedSystems and methods for transmit power controlCN104348483A *Aug 6, 2013Feb 11, 2015博通集成电路（上海）有限公司校准电路及其方法CN104348493A *Jul 25, 2014Feb 11, 2015美国亚德诺半导体公司Wideband quadrature error correction* Cited by examinerClassifications U.S. Classification375/261, 375/343International ClassificationH04L5/12Cooperative ClassificationH04L27/364European ClassificationH04L27/36B3Legal EventsDateCodeEventDescriptionMay 4, 2007ASAssignmentOwner name: MARVELL SEMICONDUCTOR, INC., CALIFORNIAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:WU, SONGPING;ZHAO, QING;SALHOTRA, ATUL;AND OTHERS;SIGNING DATES FROM 20070206 TO 20070423;REEL/FRAME:019250/0250May 9, 2007ASAssignmentFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MARVELL SEMICONDUCTOR, INC.;REEL/FRAME:019267/0308Effective date: 20070507Owner name: MARVELL INTERNATIONAL LTD., BERMUDANov 17, 2014FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services