Sec Form 3 Filing - Kwok Ephraim @ ALPHA & OMEGA SEMICONDUCTOR Ltd - 2011-07-01

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Kwok Ephraim 2. Issuer Name and Ticker or Trading Symbol ALPHA & OMEGA SEMICONDUCTOR Ltd [ AOSL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Financial Officer (Last) (First) (Middle) 475 OAKMEAD PARKWAY 3. Date of Earliest Transaction (MM/DD/YY) 07/01/2011 (Street) SUNNYVALE, CA94085 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Shares 13,750 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Employee Share Option (right to buy) $ 6 ( 1 ) 10/30/2015 Common Shares 78,330 D Employee Share Option (right to buy) $ 6 ( 1 ) 10/30/2015 Common Shares 116,670 D Employee Share Option (right to buy) $ 18 ( 2 ) 04/27/2020 Common Shares 50,000 D Employee Share Option (right to buy) $ 12.68 ( 3 ) 03/06/2021 Common Shares 34,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Kwok Ephraim 475 OAKMEAD PARKWAY SUNNYVALE, CA94085 Chief Financial Officer Signatures /s/ Ephraim Kwok 07/01/2011 Signature of Reporting Person Date

Explanation of Responses:

( 1 )As of July 1, 2011, the option is fully vested and immediately exercisable for all option shares. ( 2 )The option was granted on April 28, 2010 and becomes exercisable with respect to one-fifth (1/5) of the underlying shares on the first anniversary of the grant date, and thereafter the balance of the option shares become exercisable in a series of forty-eight (48) successive equal monthly installments. ( 3 )The option was granted on March 7, 2011 and becomes exercisable with respect to one-fifth (1/5) of the underlying shares on the first anniversary of the grant date, and thereafter the balance of the option shares become exercisable in a series of forty-eight (48) successive equal monthly installments.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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