<SEC-DOCUMENT>0001387467-21-000075.txt : 20211102
<SEC-HEADER>0001387467-21-000075.hdr.sgml : 20211102
<ACCEPTANCE-DATETIME>20211102160822
ACCESSION NUMBER:		0001387467-21-000075
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20211101
FILED AS OF DATE:		20211102
DATE AS OF CHANGE:		20211102

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Liang Yifan
		CENTRAL INDEX KEY:			0001522325

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34717
		FILM NUMBER:		211371337

	MAIL ADDRESS:	
		STREET 1:		475 OAKMEAD PARKWAY
		CITY:			SUNNYVALE
		STATE:			CA
		ZIP:			94085

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ALPHA & OMEGA SEMICONDUCTOR Ltd
		CENTRAL INDEX KEY:			0001387467
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		IRS NUMBER:				000000000
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		475 OAKMEAD PARKWAY
		CITY:			SUNNYVALE
		STATE:			CA
		ZIP:			94085
		BUSINESS PHONE:		408-830-9742

	MAIL ADDRESS:	
		STREET 1:		475 OAKMEAD PARKWAY
		CITY:			SUNNYVALE
		STATE:			CA
		ZIP:			94085

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ALPHA & OMEGA SEMICONDUCTOR LTD
		DATE OF NAME CHANGE:	20070123
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_163588368327903.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-11-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001387467</issuerCik>
        <issuerName>ALPHA &amp; OMEGA SEMICONDUCTOR Ltd</issuerName>
        <issuerTradingSymbol>AOSL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001522325</rptOwnerCik>
            <rptOwnerName>Liang Yifan</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>475 OAKMEAD PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SUNNYVALE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94085</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CFO and Corp Secretary</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2021-11-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>6600</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.90</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>159413</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2021-11-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>6600</value>
                    <footnoteId id="F4"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>35.90</value>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>153475</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Share Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>9.9</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-11-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>6600</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2022-04-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Share</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6600.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes an aggregate of 40,375 shares subject to Restricted Share Unit awards (RSU) granted on March 15, 2018, March 15, 2019, March 16, 2020, and March 15, 2021 which will be issued as such units vest in accordance with their terms, and excludes (a) 17,500 unvested common shares subject to the PSU granted on March 15, 2021, which may become vested upon achievement of certain corporate performance goals in the future and (b) 5,500 unvested common shares subject to the 2018 PSU which may be vested upon satisfaction of service-based vesting conditions by the Reporting Person.</footnote>
        <footnote id="F2">Reflects 662 shares acquired under the Issuer's Employee Stock Purchase Plan on May 14, 2021.</footnote>
        <footnote id="F3">Includes 13,125 unvested common shares subject to the 2020 PSU granted on March 16, 2020 which may be vested upon satisfaction of service-based vesting conditions by the Reporting Person.</footnote>
        <footnote id="F4">The sales were effected pursuant to a Rule 10b5-1 trading plan adopted previously by the Reporting Person.</footnote>
        <footnote id="F5">The price reported in Column 4 is the exact price at which all shares were sold.</footnote>
        <footnote id="F6">All options are fully vested and exercisable.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Yanbing Hong, attorney-in-fact for Yifan Liang</signatureName>
        <signatureDate>2021-11-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
