Document:

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                                                                   Exhibit 10.14

                            FIRST AMENDMENT TO LEASE

This First Amendment to Lease ("Amendment"), is made and entered into this 17
day of June, 1999 by and between Mission West Properties, L.P. II (formerly
known as Berg & Berg Developers), a Delaware limited partnership ("Lessor") and
Celeritek, Inc., a California Corporation ("Lessee").

                                    RECITALS

A.    Lessee currently leases from Lessor 54,672 square feet of space located at
      3236 Scott Boulevard, Santa Clara, California (the "Premises") pursuant to
      that certain lease dated April 1, 1993 (the "Lease").

B.    The term of the Lease expires September 30, 2000.

C.    Lessee has elected and Lessor has agreed to extend the subject to the
      terms and conditions set forth herein:

NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are acknowledged, the parties hereto agree to amend the
Lease as follows:

      1.    TERM: The term of the Lease is hereby extended for five years until
            September 30, 2005.

      2.    BASIC RENT: The basic rent shall be adjusted to and payable as
            follows:
<TABLE>
<CAPTION>
                                                           Basic Rent    CAC*         Total
                                                           ----------   -------     --------
<S>                                                        <C>          <C>         <C>
            October 1, 2000 through September 30, 2001      $ 76,541    $7,175*     $ 83,716
            October 1, 2001 through September 30, 2002      $ 82,008    $7,175*     $ 89,183
            October 1, 2002 through September 30, 2003      $ 97,590    $7,175*     $104,765
            October 1, 2003 through September 30, 2004      $101,493    $7,175*     $108,668
            October 1, 2004 through September 30, 2005      $105,553    $7,175*     $112,728
</TABLE>

            * Subject to annual adjustment.

      3.    BROKERAGE COMMISSION: Each party represents and warrants to the
            other party that it has not utilized or contacted a real estate
            broker or finder with respect to this Amendment and each party
            agrees to indemnify and hold each other harmless against any claim,
            cost, liability or cause of action asserted by any broker or finder
            claiming through either party. Lessor and Lessee agree that Lessor
            shall not be obligated to pay any broker leasing commissions,
            consulting fees, finders fees or any other fees or commissions
            arising out of the negotiation and execution of this Amendment or
            relating to any extended term of the Lease or to any expansion or
            relocation of the Premises.

      4.    LESSEE CERTIFICATION: As a condition of Lessor's agreeing to this
            Amendment, Lessee hereby certifies and confirms that as of the date
            of this Amendment, Lessee is not in violation of any government
            regulations, ordinances, rules or laws, including those pertaining
            to Hazardous Waste and/or Hazardous Materials.
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     5.   COMMON AREA CHARGES ("CAC"): Lessee shall pay to Lessor estimated
          taxes, insurance and gardening during the extended term (the current
          monthly estimated common area charge is $7,175).

     6.   RATIFICATION OF LEASE: Except as modified herein, the Lease is hereby
          ratified, approved and confirmed upon all the terms, covenants, and
          conditions.

     7.   AUTHORITY: Each party executing this Amendment represents and warrants
          that he or she is duly authorized to execute and deliver this
          Amendment. If executed on behalf of a corporation, that this Amendment
          is executed in accordance with the bylaws of said corporation (or a
          partnership that this Amendment is executed in accordance with the
          partnership agreement of such partnership), that no other party's
          approval or consent to such execution and delivery is required, and
          that this Amendment is binding upon said individual, corporation (or
          partnership) as the case may be in accordance with its terms.

MISSION WEST PROPERTIES, L.P., II               Celeritek, Inc.
a Delaware limited partnership                  a California corporation
By: Mission West Properties, Inc.
    A Maryland corporation

By: /s/ CARL E. BERG                            By: /s/ MICHAEL HOULIHAN
   ----------------------------                    -----------------------------
        Carl E. Berg

Title: President                                Title: VP & CFO
      -------------------------                       --------------------------

Date:    6/18/99                                Date:  6/17/99
     --------------------------                      ---------------------------<PAGE>   1
                                                                     Exhibit 4.2

COMMON STOCK                                                        COMMON STOCK

                                    CEPHEID

             INCORPORATED UNDER THE LAWS OF THE STATE OF CALIFORNIA

                                                                     [ILLEGIBLE]

                                                               CUSIP 15670R 10 7

    FULLY PAID AND NONASSESSABLE SHARES OF THE COMMON STOCK, NO PAR VALUE OF

                                    CEPHEID

transferable on the books of the Corporation by the holder hereof in person or
by duly authorized attorney upon surrender of this Certificate properly
endorsed. This Certificate is not valid unless countersigned and registered by
the Transfer Agent and Registrar.

     WITNESS the facsimile seal of the Corporation and the facsimile signature
of its duly authorized officers.

Dated:

/s/ [Signature Illegible]             [SEAL]             /s/ THOMAS GUTSHALL

SECRETARY                                                CHAIRMAN AND
                                                         CHIEF EXECUTIVE OFFICER
<PAGE>   2
                                    CEPHEID

     A statement of rights, preferences, privileges and restrictions granted to
or imposed upon the respective classes or series of shares and upon the holders
thereof as established, from time to time, by the Articles of Incorporation of
the Corporation and by any certificate of determination, and the number of
shares constituting each class and series and the designations thereof, may be
obtained by the holder hereof upon request and without charge from the Secretary
of the Corporation at its corporate headquarters.

     The following abbreviations, when used in the inscription on the face of
this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

<TABLE>
     <S>                                                <C>
     TEN COM  - as tenants in common                    UNIF GIFT MIN ACT - _______________ Custodian _______________
                                                                                 (Cust)                   (Minor)
     TEN ENT  - as tenants by the entireties                                under Uniform Gifts to Minors
                                                        Act _________________________
     JT TEN   - as joint tenants with right of                                         (State)
                survivorship and not as tenants         UNIF TRF MIN ACT - ________________ Custodian (until age ____)
                in common                                                        (Cust)
                                                                           ___________________ under Uniform Transfers
                                                                                 (Minor)
</TABLE>

    Additional abbreviations may also be used though not in the above list.

FOR VALUE RECEIVED, _______________________ hereby sell, assign and transfer
unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
    IDENTIFYING NUMBER OF ASSIGNEE
______________________________________

______________________________________

________________________________________________________________________________
 (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

________________________________________________________________________________

________________________________________________________________________________

_________________________________________________________________________ Shares
of the capital stock represented by the within Certificate, and do hereby
irrevocably constitute and appoint

_______________________________________________________________________ Attorney
to transfer the said stock on the books of the within named Corporation with
full power of substitution in the premises.

Dated ________________________________

                                       X _______________________________________

                                       X _______________________________________
                                       THE SIGNATURE OF THIS ASSIGNMENT MUST
                                       CORRESPOND WITH THE NAME(S) AS WRITTEN
                              NOTICE:  UPON THE FACE OF THE CERTIFICATE IN EVERY
                                       PARTICULAR, WITHOUT ALTERATION OR
                                       ENLARGEMENT OR ANY CHANGE WHATSOEVER.

SIGNATURE(S) GUARANTEED

By _______________________________________________________________________
THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION
(BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH
MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM), PURSUANT
TO S.E.C. RULE 17Ad-15.

--------------------------------------- ----------------------------------------
       AMERICAN BANK NOTE COMPANY        PRODUCTION ??????????????????????????
         ???? AND ????? STREET                  ??? ??? ?? MAY 2, ????
         PHILADELPHIA, PA ?????                      CEPHEID, INC.
             (???) ???-????                          ? ??????? ???
--------------------------------------- ----------------------------------------
     SALES: ?? ??????  ??? ??? ????          OPERATOR:             DATE:
--------------------------------------- ----------------------------------------
  /?????? ??/LIVE JOBS/C/??????? ?????                 Rev 1
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