-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 QCxKqyXeoxQch/wr3Y9I7g==

<SEC-DOCUMENT>0001246360-10-000680.txt : 20100209
<SEC-HEADER>0001246360-10-000680.hdr.sgml : 20100209
<ACCEPTANCE-DATETIME>20100209175928
ACCESSION NUMBER:		0001246360-10-000680
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090731
FILED AS OF DATE:		20100209
DATE AS OF CHANGE:		20100209

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CADENCE DESIGN SYSTEMS INC
		CENTRAL INDEX KEY:			0000813672
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				770148231
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1229

	BUSINESS ADDRESS:	
		STREET 1:		2655 SEELY ROAD BLDG 5
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95134
		BUSINESS PHONE:		4089431234

	MAIL ADDRESS:	
		STREET 1:		555 RIVER OAKS PARKWAY
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95134

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ECAD INC /DE/
		DATE OF NAME CHANGE:	19880609

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			TAN LIP BU
		CENTRAL INDEX KEY:			0001008463

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10606
		FILM NUMBER:		10585593

	MAIL ADDRESS:	
		STREET 1:		ONE CALIFORNIA STREET 28TH FLOOR
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94111

	FORMER NAME:	
		FORMER CONFORMED NAME:	TAN LIP BU ET AL
		DATE OF NAME CHANGE:	19960217
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-07-31</periodOfReport>

    <notSubjectToSection16>false</notSubjectToSection16>

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        <issuerName>CADENCE DESIGN SYSTEMS INC</issuerName>
        <issuerTradingSymbol>CDNS</issuerTradingSymbol>
    </issuer>

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            <rptOwnerName>TAN LIP BU</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2655 SEELY AVENUE, BLDG 5</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN JOSE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95134</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>President and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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            <ownershipNature>
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            <transactionDate>
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            <transactionCoding>
                <transactionFormType>4</transactionFormType>
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                <equitySwapInvolved>false</equitySwapInvolved>
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                <transactionShares>
                    <value>38784</value>
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                <transactionPricePerShare>
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            <transactionDate>
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            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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                <equitySwapInvolved>false</equitySwapInvolved>
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                <transactionAcquiredDisposedCode>
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            <transactionDate>
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            <transactionCoding>
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                <equitySwapInvolved>false</equitySwapInvolved>
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                </transactionShares>
                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
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                    <value>D</value>
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                </directOrIndirectOwnership>
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    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Non-Qualified Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>5.6</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-02-08</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
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                <transactionShares>
                    <value>800000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
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            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-02-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
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                <underlyingSecurityShares>
                    <value>800000</value>
                </underlyingSecurityShares>
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                    <value>800000</value>
                </sharesOwnedFollowingTransaction>
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    </derivativeTable>

    <footnotes>
        <footnote id="F1">Amount of Shares Beneficially Owned Following Reported Transactiion includes 1,214 shares of common stock acquired by the reporting person through the Cadence Design Systems, Inc. Employee Stock Purchase Plan on January 29, 2010.</footnote>
        <footnote id="F2">Shares withheld to satisfy tax obligations arising out of vesting of restricted stock.</footnote>
        <footnote id="F3">Grant of performance based incentive stock.</footnote>
        <footnote id="F4">Option vests at a rate of 1/48th per month.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>James J. Cowie, Attorney-in-Fact for Lip-Bu Tan</signatureName>
        <signatureDate>2010-02-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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