UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                                (Amendment No.    1   )*
                                                ------

                            MICROCHIP TECHNOLOGY INC
--------------------------------------------------------------------------------
                                (Name of Issuer)


                     Common Stock, $.01 par value per share
--------------------------------------------------------------------------------
                         (Title of Class of Securities)


                                  US5950171042
--------------------------------------------------------------------------------
                                 (CUSIP Number)



                                December 31, 2004
--------------------------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)


Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

         [ X ]   Rule 13d-1(b)

         [   ]   Rule 13d-1(c)

         [   ]   Rule 13d-1(d)


*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).








                                  SCHEDULE 13G

CUSIP No.         US5950171042


----------------------------------------------------------------------------------------------------------------------------
      

          1.   Names of Reporting Persons.  I.R.S.  Identification Nos. of above
               persons (entities only). 
               AMVESCAP PLC

----------------------------------------------------------------------------------------------------------------------------

          2.   Check the Appropriate Box if a Member of a Group (see
               Instructions) 
               (a)
               (b)
              
----------------------------------------------------------------------------------------------------------------------------

          3.   SEC Use Only  _______________________________________________

----------------------------------------------------------------------------------------------------------------------------

         4.       Citizenship or Place of Organization
                  AMVESCAP PLC:  England
                  AIM Advisors, Inc:  United States
                  AIM Private Asset Management, Inc.:  United States
                  INVESCO Asset Management, S.A.:  France
                  INVESCO Asset Management Limited:  England
                  AIM Capital Management, Inc.:  United States
                  AIM Funds Management, Inc.:  United States
                  INVESCO Institutional (N.A.), Inc.:  United States
                  INVESCO Asset Management GmbH:  Germany
                  Stein Roe Investment Counsel, Inc.:  United States

----------------------------------------------------------------------------------------------------------------------------

                                    5.      Sole Voting Power 16,271,164:  Such shares are held by the following 
                                            entities in the respective amounts listed  AIM Advisors, Inc 
                                            7,238,326, AIM Private Asset Management, Inc. 790,310, INVESCO Asset 
                                            Management, S.A. 931, INVESCO Asset Management Limited 600, AIM 
                                            Capital Management, Inc. 5,820,877,AIM Funds Management, Inc. 20,000, 
                                            INVESCO Institutional (N.A.), Inc. 1,313,509, INVESCO Asset Management GmbH 
                                            21,599,Stein Roe Investment Counsel, Inc. 1,065,012    

Number of Shares           --------------------------------------------------------------------------------------------------
Beneficially Owned
by Each Reporting                   6.      Shared Voting Power       _______________
Person With
                           --------------------------------------------------------------------------------------------------

                                    7.      Sole Dispositive Power     16,271,164:  Such shares are held by the following 
                                            entities in the respective amounts listed  AIM Advisors, Inc 
                                            7,238,326, AIM Private Asset Management, Inc. 790,310, INVESCO Asset 
                                            Management, S.A. 931, INVESCO Asset Management Limited 600, AIM 
                                            Capital Management, Inc. 5,820,877,AIM Funds Management, Inc. 20,000, 
                                            INVESCO Institutional (N.A.), Inc. 1,313,509, INVESCO Asset Management GmbH 
                                            21,599,Stein Roe Investment Counsel, Inc. 1,065,012

                           --------------------------------------------------------------------------------------------------

                                    8.      Shared Dispositive Power     _______________






----------------------------------------------------------------------------------------------------------------------------
     
          9.   Aggregate  Amount  Beneficially  Owned by Each  Reporting  Person
               16,271,164

----------------------------------------------------------------------------------------------------------------------------


          10.  Check if the Aggregate  Amount in Row (9) Excludes Certain Shares
               (See Instructions) N/A


----------------------------------------------------------------------------------------------------------------------------

          11.  Percent of Class Represented by Amount in Row (9)        7.89% 
                                                                        -----


----------------------------------------------------------------------------------------------------------------------------

          12.  Type of Reporting Person (See  Instructions)  
               IA, HC. See Items 2 and 3 of this statement.







                                  SCHEDULE 13G


                                        
Item 1(a)         Name of Issuer:
                  MICROCHIP TECHNOLOGY INC


Item 1(b)         Address of Issuer's Principal Executive Offices:
                  2355 West Chandler Boulevard
                  Chandler, AZ 85224-6199


Item 2(a)         Name of Person Filing:
                  AMVESCAP PLC

                  In accordance with Securities and Exchange Commission Release
                  No. 34-39538 (January 12, 1998), this statement on Schedule
                  13G or amendment thereto is being filed by AMVESCAP PLC
                  ("AMVESCAP"), a U.K. entity, on behalf of itself and its
                  subsidiaries listed in Item 4 of the cover of this statement.
                  AMVESCAP through such subsidiaries provides investment
                  management services to institutional and individual investors
                  worldwide.

                  Executive officers and directors of AMVESCAP or its
                  subsidiaries may beneficially own shares of the securities of
                  the issuer to which this statement relates (the "Shares"), and
                  such Shares are not reported in this statement. AMVESCAP and
                  its subsidiaries disclaim beneficial ownership of Shares
                  beneficially owned by any of their executive officers and
                  directors. Each of AMVESCAP's direct and indirect subsidiaries
                  also disclaim beneficial ownership of Shares beneficially
                  owned by AMVESCAP and any other subsidiary.


Item 2(b)         Address of Principal Business Office:
                  11 Devonshire Square
                  London EC2M 4YR
                  England


Item 2(c)         Citizenship:
                  See the response to Item 2(a) of this statement.


Item 2(d)         Title of Class of Securities:
                  Common Stock, $.01 par value per share


Item 2(e)         CUSIP Number:
                  US5950171042


Item 3            Type of Reporting Person:
                  An investment adviser in accordance with section 240.13d-1(b)(1)(ii)(E)
                  A parent holding company or control person in accordance with section 240.13d-1(b)(1)(ii)(G)

                  As noted in Item 2 above, AMVESCAP is making this filing on
                  behalf of its subsidiaries listed herein. Each of these
                  entities is either an investment adviser registered with the
                  United States Securities Exchange Commission under Section 203
                  of the Investment Advisers Act of 1940, as amended, or under
                  similar laws of other jurisdictions. AMVESCAP is a holding
                  company.







                                   
Item 4            Ownership:
                  Please see responses to Items 5-8 on the cover of this
                  statement which are incorporated herein by reference.


Item 5            Ownership of Five Percent or Less of a Class:
                  N/A


Item 6            Ownership of More than Five Percent on Behalf of Another Person:
                  N/A


Item 7            Identification and Classification of the Subsidiary Which Acquired the Security Being Reporting 
                  on By the Parent Holding Company:
                  Please see Item 3 of this statement, which is incorporated herein by reference.


Item 8            Identification and Classification of Members of the Group:
                  N/A


Item 9            Notice of Dissolution of a Group:
                  N/A


Item 10           Certification:
                  By signing below I certify that, to the best of my knowledge
                  and belief, the securities referred to above were acquired and
                  are held in the ordinary course of business and were not
                  acquired and are not held for the purpose of or with the
                  effect of changing or influencing the control of the issuer of
                  the securities and were not acquired and are not held in
                  connection with or as a participant in any transaction having
                  that purpose or effect.

                  Signature:
                  After reasonable inquiry and to the best of my knowledge and
                  belief, I certify that the information set forth in this
                  statement is true, complete and correct.


                                                                       February 14, 2005                  
                                                              --------------------------------------------
                                                                       Date



                                                                       /s/  HAL LIEBES                    
                                                              --------------------------------------------
                                                                       Signature



                                                              Hal Liebes                                           
                                                              Group Compliance Officer                             
                                                              AMVESCAP PLC