Washington, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                             (Amendment No. ____)*

                       Cambridge Display Technology, Inc.
                                (Name of Issuer)

                                  Common Stock
                         (Title of Class of Securities)

                                 (CUSIP Number)

                                December 31, 2006
             (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

                                  SCHEDULE 13G

CUSIP No. 132193103

1.   Names of Reporting Persons.

     I.R.S. Identification Nos. of above persons (entities only).

     PowerShares Capital Management LLC
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
     PowerShares Capital Management LLC: United States
               5.   Sole Voting Power 1,144,225: Such shares are held by the
                    following entities in the respective amounts listed:

                    PowerShares Capital Management LLC 1,144,225
  Number of    6.   Shared Voting Power
Beneficially        -0-
  Owned By     -----------------------------------------------------------------
    Each       7.   Sole Dispositive Power 1,144,225: Such shares are held by
  Reporting         the following entities in the respective amounts listed:
 Person With
                    PowerShares Capital Management LLC 1,144,225
               8.   Shared Dispositive Power

9.   Aggregate Amount Beneficially Owned by Each Reporting Person

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

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

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:

            Cambridge Display Technology, Inc.

Item 1(b)   Address of Issuer's Principal Executive Offices:

            Building 2020
            Cambourne Business Park
            Cambridge, United Kingdom

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:

            30 Finsbury Square
            London EC2A 1AG

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:


Item 3      If this statement is filed pursuant to ss240.13d-1(b) or
            240.13d-2(b) or (c), check whether the person filing is a:

      (e)   [x]   An investment adviser in accordance with section

      (g)   [x]   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
            and 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:

            If this statement is being filed to report the fact that as of the
            date hereof the reporting person has ceased to be the beneficial
            owner of more than five percent of the class of securities, check
            the following [ ]

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


Item 7      Identification and Classification of the Subsidiary Which Acquired
            the Security Being reported on By the Parent Holding Company:

            Please see Item 3 of this statement, which is incorporated herein by

Item 8      Identification and Classification of Members of the Group:


Item 9      Notice of Dissolution of a Group:


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.


            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.


                                        AMVESCAP PLC

                                        By: /s/ Lisa Brinkley
                                            Lisa Brinkley
                                            Chief Compliance Officer

                                  Exhibit Index

Exhibit A Joint Filing Agreement