EXHIBIT 2.2

                              CERTIFICATE OF MERGER
                                        
                                     MERGING

                                 QT CORPORATION

                                  WITH AND INTO

                                 SPEEDSIM, INC.

                        ________________________________

           Pursuant to Section 251 of the General Corporation Law of 
                              the State of Delaware
                        ________________________________

     SpeedSim, Inc., a Delaware corporation ("SpeedSim"), DOES HEREBY CERTIFY 
AS FOLLOWS:

     FIRST:  That SpeedSim was incorporated on February 1, 1995, pursuant to 
the Delaware General Corporation Law (the "Delaware Law"), and QT 
Corporation. ("QT") was incorporated on January 10, 1997 pursuant to the 
Delaware Law.

     SECOND:  That an Agreement and Plan of Reorganization (the 
"Reorganization Agreement"), dated as of January 16, 1997, among Quickturn 
Design Systems, Inc., a Delaware corporation, SpeedSim and QT, setting forth 
the terms and conditions of the merger of QT with and into SpeedSim (the 
"Merger"), has been approved, adopted, certified, executed and acknowledged 
by each of the constituent corporations in accordance with the requirements 
of Section 251 of the Delaware Law.

     THIRD:  That the surviving corporation (the "Surviving Corporation") 
shall be SpeedSim, which shall retain the name "SpeedSim, Inc."

     FOURTH: That pursuant to the Reorganization Agreement, the Certificate 
of Incorporation of SpeedSim, Inc. shall be amended on the date of the Merger 
to read in its entirety as set forth on EXHIBIT A attached hereto.

From and after the effective time of the Merger, the Certificate of 
Incorporation of SpeedSim, as so amended, shall continue to be the 
Certificate of Incorporation of the surviving corporation, until amended as 
provided by law. 


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      FIFTH:  That an executed copy of the Reorganization Agreement is on 
file at the principal place of business of the Surviving Corporation at the 
following address:

                    11 School Street
                    North Chelmsford, Massachusetts 01863

     SIXTH:  That a copy of the Reorganization Agreement will be furnished by 
the Surviving Corporation, on request and without cost, to any stockholder of 
any constituent corporation.

     SEVENTH:  That the Merger shall become effective upon the filing of this 
Certificate of Merger with the Secretary of State of the State of Delaware.

     IN WITNESS WHEREOF, SpeedSim has caused this Certificate of Merger to be 
executed in its corporate name as of the 7th day of February 1997.

                         SPEEDSIM, INC.



                         By: /s/ Donald McInnis          
                             ----------------------------------------------
                             Donald McInnis
                             President



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                                    EXHIBIT A

                          CERTIFICATE OF INCORPORATION
                                       OF
                                 SPEEDSIM, INC.

                                        

                                   ARTICLE 1.

          The name of the corporation is SpeedSim, Inc. (the "Corporation").

                                   ARTICLE 2.

          The address of the Corporation's registered office in the State of 
Delaware is Corporation Trust Center, 1209 Orange Street, Wilmington, County 
of New Castle.  The name of its registered agent at such address is The 
Corporation Trust Company.

                                   ARTICLE 3.

          The nature of the business or purposes to be conducted or promoted 
by the Corporation is to engage in any lawful act or activity for which 
corporations may be organized under the General Corporation Law of Delaware.

                                   ARTICLE 4.

          The total number of shares of stock which the corporation shall 
have authority to issue is Ten Thousand (10,000) and the par value of each of 
such shares is One Cent ($.01) amounting in the aggregate to One Hundred 
Dollars ($100.00).

                                   ARTICLE 5.

          The board of directors is authorized to make, alter or repeal the 
by-laws of the corporation.  Election of directors need not be by written 
ballot.

                                   ARTICLE 6.

          A director of the corporation shall not be personally liable to the 
corporation or its stockholders for monetary damages for breach of fiduciary 
duty as a director except for liability (i) for any breach of the director's 
duty of loyalty to the corporation or its stockholders, (ii) for acts or 
omissions not in good faith or which involve intentional misconduct or a 
knowing violation of law, (iii) under Section 174 of the Delaware General 
Corporation Law, or (iv) for any transaction from which the director derived 
any improper personal benefit.


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                                   ARTICLE 7.

          The Corporation shall indemnify its officers, directors, employees 
and agents to the extent permitted by the General Corporation Law of 
Delaware. 


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