Document:

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                                                                     EXHIBIT 4.5

                                 AMENDMENT NO. 4
                                       TO
                        PREFERRED SHARES RIGHTS AGREEMENT

        THIS AMENDMENT NO. 4 TO PREFERRED SHARES RIGHTS AGREEMENT dated as of
July 17, 2002 (this "AMENDMENT") is made between CATALYST SEMICONDUCTOR, INC., a
Delaware corporation (the "COMPANY"), and EquiServe Trust Company, N.A., as
rights agent (the "RIGHTS AGENT").

                                    RECITALS

        A. The Company and the Rights Agent are parties to a Preferred Shares
Rights Agreement dated as of December 3, 1996 as amended by Amendment No. 1
thereto dated as of May 22, 1998, by Amendment No. 2 thereto dated as of
September 14, 1998 and by Amendment No. 3 thereto dated as of September 27, 2001
(collectively, the "RIGHTS AGREEMENT").

        B. Elex NV ("ELEX") previously purchased an aggregate of 5,500,000
shares of Common Stock from the Company and the Company entered into Amendments
No. 1 and 2 in order that neither Elex nor its Affiliates or Associates would be
deemed an Acquiring Person for purposes of the Rights Agreement in connection
with such purchases.

        C. The Company's Board of Directors has previously approved the grant of
options to purchase shares of the Company's Common Stock to Mr. Roland
Duchatelet in connection with his position as a member of the Company's Board of
Directors; provided that the effectiveness of such grants is contingent upon an
amendment to the Rights Agreement being made in order that neither Elex (or its
Affiliate or Associates) nor Mr. Duchatelet (or his Affiliates or Associates)
would be deemed an Acquiring Person for purposes of the Rights Agreement in
connection with the grant of such options or their subsequent exercise.

        D. Pursuant to Section 27 of the Rights Agreement, the Board of
Directors of the Company has determined that an amendment to the Rights
Agreement as set forth herein is necessary and desirable to reflect the
foregoing and the Company and the Rights Agent desire to evidence such amendment
in writing.

        NOW, THEREFOR, the parties hereto agree as follows:

        1. Amendment of Section 1(a). Section 1(a) of the Rights Agreement is
amended to replace the last sentence thereof with the following sentence:

        "Notwithstanding anything in this Rights Agreement to the contrary,
        neither Elex NV ("ELEX") (or its Affiliates or Associates) nor Roland
        Duchatelet (or his Affiliates or Associates) shall be deemed to be an
        Acquiring Person solely by virtue of the announcement, occurrence or
        continuance of (i) the execution of the

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        Common Stock Purchase Agreement dated as of May 26, 1998 between Elex
        and the Company (the "PURCHASE AGREEMENT"), (ii) the execution of the
        Common Stock Purchase Agreement dated as of September 14, 1998 between
        Elex and the Company (the "SECOND PURCHASE AGREEMENT"), (iii) the
        issuance to Elex of 1,500,000 shares of Common Stock of the Company in
        accordance with the terms of the Purchase Agreement and 4,000,000 shares
        of Common Stock of the Company in accordance with the terms of the
        Second Purchase Agreement, (iv) the grant of options to purchase shares
        of the Company's Common Stock to Mr. Roland Duchatelet in connection
        with his position as a member of the Board of Directors of the Company,
        (v) the issuance of shares of Common Stock upon the exercise by Mr.
        Roland Duchatelet of any options granted to Mr. Duchatelet in connection
        with his position as a member of the Board of Directors of the Company,
        (vi) any purchase by Elex (or its Affiliates or Associates) or Mr.
        Duchatelet (or his Affiliates or Associates) of shares of the Company's
        Common Stock in the open market from time to time, so long as any such
        purchase of shares does not cause Elex (and its Affiliates and
        Associates) and Mr. Duchatelet (and his Affiliates and Associates)
        collectively at the time of such purchase to be or to become deemed to
        be the Beneficial Owner of more than 5,500,000 shares of the Company's
        Common Stock in the aggregate (as appropriately adjusted for stock
        splits, stock dividends and the like) (together with the shares
        described in clauses (iii), (iv) and (v) above, the "PERMITTED SHARES"),
        or (vii) Elex (or its Affiliates or Associates) or Mr. Duchatelet (or
        his Affiliates or Associates) holding or being deemed a Beneficial Owner
        of the Permitted Shares; provided, however, that if Elex (or its
        Affiliates or Associates) or Mr. Duchatelet (or his Affiliates or
        Associates), at any time after the issuance or purchase of any and all
        Permitted Shares, shall be or become deemed to be the Beneficial Owner
        of shares of Common Stock of the Company other than the Permitted
        Shares, then such exemptions from being deemed an Acquiring Person
        contained in this sentence shall not be applicable.

    2. Section 1(g) shall be deleted in its entirety and replaced with the
words "Intentionally Omitted."

    3. Section 1(h) shall be deleted in its entirety and replaced with the
following:

        "(h) "DISTRIBUTION DATE" shall mean the earlier of (i) the Close of
        Business on the tenth day (or such later date as may be determined by
        action of the Board of Directors prior to such time as any person
        becomes an Acquiring Person) after the Shares Acquisition Date (or, if
        the tenth day after the Shares Acquisition Date occurs before the Record
        Date, the Close of Business on the Record Date) or (ii) the Close of
        Business on the tenth day (or such later date as may be determined by
        action of the Board of Directors prior to such time as any person
        becomes an Acquiring Person) after the date that a tender or exchange
        offer by any Person (other than the Company, any Subsidiary of the
        Company, any employee benefit plan of the Company or of any Subsidiary
        of the Company, or

                                      -2-
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        any Person or entity organized, appointed or established by the Company
        for or pursuant to the terms of any such plan) is first published or
        sent or given within the meaning of Rule 14d-2(a) of the General Rules
        and Regulations under the Exchange Act, if, assuming the successful
        consummation thereof, such Person would be the Beneficial Owner of 15%
        or more of the shares of Common Stock then outstanding."

    4. Section 1(l) shall be deleted in its entirety and replaced with the
following:

        "(l) "PERMITTED OFFER" shall mean a tender offer for all outstanding
        Common Shares made in the manner prescribed by Section 14(d) of the
        Exchange Act and the rules and regulations promulgated thereunder;
        provided, however, that the Board (as determined prior to the purchase
        of such shares under such tender offer in its discretion by the vote of
        a majority of Directors then in office) has determined that the offer is
        both adequate and otherwise in the best interests of the Company and its
        stockholders (taking into account all factors that the Board deems
        relevant, including without limitation prices that could reasonably be
        achieved if the Company or its assets were sold on an orderly basis
        designed to realize maximum value)."

    5. Section 2 shall be deleted in its entirety and replaced with the
following:

        "Section 2. Appointment of Rights Agent. The Company hereby appoints the
        Rights Agent to act as agent for the Company in accordance with the
        terms and conditions hereof, and the Rights Agent hereby accepts such
        appointment. The Company may from time to time appoint such co-Rights
        Agents as it may deem necessary or desirable, upon ten (10) days' prior
        written notice to the Rights Agent. The Rights Agent shall have no duty
        to supervise, and shall in no event be liable for the acts or omissions
        of any such co-Rights Agent."

    6. Section 18(a) shall be deleted in its entirety and replaced with the
following:

        "(a) The Company agrees to pay to the Rights Agent such compensation as
        shall be agreed to in writing between the Company and the Rights Agent
        for all services rendered by it hereunder and, from time to time, on
        demand of the Rights Agent, its reasonable expenses and counsel fees and
        expenses and other disbursements incurred in the administration and
        execution of this Agreement and the exercise and performance of its
        duties hereunder. The Company also agrees to indemnify the Rights Agent
        for, and to hold it harmless against, any loss, liability or expense,
        incurred without gross negligence, bad faith or willful misconduct on
        the part of the Rights Agent, for anything done or omitted by the Rights
        Agent in connection with the acceptance and administration of this
        Agreement, including the costs and expenses of defending against any
        claim of liability in the premises. The provisions of this Section 18(a)
        shall survive the termination of this Agreement."

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    7. Section 20(c) shall be deleted in its entirety and replaced with the
following:

        "(c) The Rights Agent shall be liable hereunder to the Company and any
        other Person only for its own gross negligence, bad faith or willful
        misconduct."

    8. Section 23(a) shall be deleted in its entirety and replaced with the
following:

        "(a) The Company may, at its option, by action of a majority of the
        Company's Board of Directors, at any time prior to the Close of Business
        on the earlier of (i) the tenth day following the Shares Acquisition
        Date or (ii) the Final Expiration Date, redeem all but not less than all
        the then outstanding Rights at a redemption price of $0.01 per Right,
        appropriately adjusted to reflect any stock split, stock dividend or
        similar transaction occurring after the date hereof (such redemption
        price being herein referred to as the "Redemption Price") and the
        Company may, at its option, pay the Redemption Price either in Common
        Shares (based on the current per share market price thereof (as
        determined pursuant to Section 11(d) hereof) at the time of redemption)
        or cash."

    9. Section 24(a) shall be deleted in its entirety and replaced with the
following:

        "(a) Subject to applicable laws, rules and regulations, and subject to
        subsection (c) below, the Company may, at its option, by majority vote
        of the Board of Directors, at any time after the occurrence of a
        Triggering Event, exchange all or part of the then outstanding and
        exercisable Rights (which shall not include Rights that have become void
        pursuant to the provisions of Section 7(e) hereof) for Common Shares at
        an exchange ratio of one Common Share per Right, appropriately adjusted
        to reflect any stock split, stock dividend or similar transaction
        occurring after the date hereof (such exchange ratio being hereinafter
        referred to as the "RATIO OF EXCHANGE"). Notwithstanding the foregoing,
        the Board of Directors shall not be empowered to effect such exchange at
        any time after any Person (other than the Company, any Subsidiary of the
        Company, any employee benefit plan of the Company or any such
        Subsidiary, or any entity holding Common Shares for or pursuant to the
        terms of any such plan), together with all Affiliates and Associates of
        such Person, becomes the Beneficial Owner of 50% or more of the Common
        Shares then outstanding."

    10. Section 26 shall be deleted in its entirety and replaced with the
following:

        "Section 26. Notices. Notices or demands authorized by this Agreement to
        be given or made by the Rights Agent or by the holder of any Rights
        Certificate to or on the Company shall be sufficiently given or made if
        sent by first-class mail, postage prepaid, addressed (until another
        address is filed in writing with the Rights Agent) as follows:

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                          Catalyst Semiconductor, Inc.
                              1250 Borregas Avenue
                               Sunnyvale, CA 94089
                              Attention: President

        Subject to the provisions of Section 21 hereof, any notice or demand
        authorized by this Agreement to be given or made by the Company or by
        the holder of any Rights Certificate to or on the Rights Agent shall be
        sufficiently given or made if sent by first-class mail, postage prepaid
        addressed (until another address is filed in writing with the Company)
        as follows:

                              Bank of Boston, N.A.
                    c/o Boston EquiServe Limited Partnership
                                150 Royall Street
                           Canton, Massachusetts 02021
                        Attention: Client Administration

        Notices or demands authorized by this Agreement to be given or made by
        the Company or the Rights Agent to or on the holder of any Rights
        Certificate shall be sufficiently given or made if sent by first-class
        mail, postage prepaid, addressed to such holder at the address of such
        holder as shown on the registry books of the Company."

    11. Section 27 shall be deleted in its entirety and replaced with the
following:

        "Section 27. Supplemental Amendments. Prior to the Distribution Date,
        the Company may supplement or amend this Agreement in any respect
        without the approval of any holders of Rights and the Rights Agent
        shall, if the Company so directs, execute such supplement or amendment.
        From and after the Distribution Date, the Company and the Rights Agent
        may from time to time supplement or amend this Agreement without the
        approval of any holders of Rights in order to (i) cure any ambiguity,
        (ii) correct or supplement any provision contained herein which may be
        defective or inconsistent with any other provisions herein, (iii)
        shorten or lengthen any time period hereunder or (iv) to change or
        supplement the provisions hereunder in any manner that the Company may
        deem necessary or desirable and that shall not adversely affect the
        interests of the holders of Rights (other than an Acquiring Person or an
        Affiliate or Associate of an Acquiring Person); provided, this Agreement
        may not be supplemented or amended to lengthen, pursuant to clause (iii)
        of this sentence, (A) a time period relating to when the Rights may be
        redeemed at such time as the Rights are not then redeemable or (B) any
        other time period unless such lengthening is for the purpose of
        protecting, enhancing or clarifying the rights of, and/or the benefits
        to, the holders of Rights. Upon the delivery of a certificate from an
        appropriate officer of the Company that states that the proposed
        supplement or amendment is

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        in compliance with the terms of this Section 27, the Rights Agent shall
        execute such supplement or amendment. Prior to the Distribution Date,
        the interests of the holders of Rights shall be deemed coincident with
        the interests of the holders of Common Shares. Notwithstanding any other
        provision hereof, the Rights Agent's consent must be obtained regarding
        any amendment or supplement pursuant to this Section 27 which alters the
        Rights Agent's rights or duties, which consent shall not be unreasonably
        withheld."

    12. Section 29 shall be deleted in its entirety and replaced with the
following:

        "Section 29. Determinations and Actions by the Board of Directors, etc.
        For all purposes of this Agreement, any calculation of the number of
        Common Shares outstanding at any particular time, including for purposes
        of determining the particular percentage of such outstanding Common
        Shares of which any Person is the Beneficial Owner, shall be made in
        accordance with the last sentence of Rule 13d-3(d)(1)(i) of the General
        Rules and Regulations under the Exchange Act. The Board of Directors of
        the Company shall have the exclusive power and authority to administer
        this Agreement and to exercise all rights and powers specifically
        granted to the Board, or the Company, or as may be necessary or
        advisable in the administration of this Agreement, including, without
        limitation, the right and power to (i) interpret the provisions of this
        Agreement and (ii) make all determinations deemed necessary or advisable
        for the administration of this Agreement (including a determination to
        redeem or not redeem the Rights or to amend the Agreement). All such
        actions, calculations, interpretations and determinations (including,
        for purposes of clause (y) below, all omissions with respect to the
        foregoing) which are done or made by the Board in good faith, shall (x)
        be final, conclusive and binding on the Company, the Rights Agent, the
        holders of the Rights Certificates and all other parties and (y) not
        subject the Board to any liability to the holders of the Rights."

    13. Effectiveness. This Amendment shall be deemed effective as of July 17,
2002 as if executed on such date. Except as amended hereby, the Rights Agreement
shall remain in full force and effect and shall be otherwise unaffected hereby.

    14. Miscellaneous. This Amendment shall be deemed to be a contract made
under the laws of the State of Delaware and for all purposes shall be governed
by and construed in accordance with the laws of such state applicable to
contracts to be made and performed entirely within such state. This Amendment
may be executed in any number of counterparts, each of such counterparts shall
for all purposes be deemed to be an original, and all such counterparts shall
together constitute but one and the same instrument. If any provision, covenant
or restriction of this Amendment is held by a court of competent jurisdiction or
other authority to be invalid, illegal or unenforceable, the remainder of the
terms, provisions, covenants and restrictions of this Amendment shall remain in
full force and effect and shall in no way be affected, impaired or invalidated.

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                            [Signature Page Follows]

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<PAGE>

        IN WITNESS WHEREOF the undersigned have executed this Amendment No. 4 to
the Rights Agreement as of the date first above written.

                                        CATALYST SEMICONDUCTOR, INC.

                                        By:          /s/ Radu M. Vanco
                                           -------------------------------------
                                           Radu M. Vanco
                                           President & Chief Executive Officer

ATTEST:

/s/ T. E. Gay III
---------------------------------
    Thomas E. Gay III
    Vice President Finance &
    Chief Financial Officer

                                        EQUISERVE TRUST COMPANY, N.A.

                                        By:        /s/ Michael J. Connor
                                           -------------------------------------
                                           Name:  Michael J. Connor
                                           Title: Client Administration,
                                                  Managing Director

ATTEST:

        /s/ Dawn Engelhardt
---------------------------------
Name:  Dawn Engelhardt
Title:  Account Manager

                      [SIGNATURE PAGE TO AMENDMENT NO. 4 TO
                       PREFERRED SHARES RIGHTS AGREEMENT]<PAGE>

                                                                   EXHIBIT 10.77

                          CATALYST SEMICONDUCTOR, INC.
                               Severance Agreement

This Severance Agreement ("Agreement") is made as of this 26 day of April, 2001
between Gelu Voicu ("Employee") and Catalyst Semiconductor, Inc.
("Corporation").

                                   WITNESSETH

WHEREAS, Employee is employed by the Corporation.

WHEREAS, the Corporation and Employee mutually desire to enter into a severance
agreement with respect to Employee's employment by the Corporation.

NOW, THEREFORE, in consideration of the mutual convents hereinafter contained,
the Corporation and Employee agree as follows:

1)      INVOLUNTARY TERMINATION.

        For the purpose of this Agreement, "Involuntary Termination" include
        termination for reasons other than for cause of Employee's resignation
        following (I) a reduction in compensation which is not in proportion to
        any salary reduction program approved by the Board which affects all
        officers of Employer; (II) a reduction in material benefits; (III) a
        reduction in job responsibilities (being offered a position lower than
        VP reporting directly to the CEO); or (IV) the relocation of Employee's
        primary place of business without Employee's consent to a location more
        than fifty (50) miles from Employee's primary place of business
        immediately prior to such relocation.

        If Employee's employment is terminated as a result of Involuntary
        Termination other than for cause, at any time prior to three years from
        this date, Employee will be entitled to consideration as defined below:

2)      SEVERANCE BENEFITS FOR INVOLUNTARY TERMINATION FOLLOWING A CHANGE OF
        CONTROL.

        a)      Employee shall be entitled to hundred percent (100%) of his
                current compensation payable in 12 equal monthly installments,
                commencing one month after the termination date.

        b)      All outstanding unvested stock options shall immediately vest as
                of the date of termination and shall remain exercisable for a
                period of three years after said date.

        c)      In addition, as the termination date, Employee shall be entitled
                to receive any unpaid salary and accrued vacation.

        d)      Change of control is defined as any sale of substantially all of
                the Company's assets, a sale of a majority of its shares or a
                merger or consolidation where the

<PAGE>

                existing shareholders do not control at least 50% of the total
                voting power after the event.

3)      SEVERANCE BENEFITS FOR INVOLUNTARY TERMINATION APART FROM A CHANGE OF
        CONTROL.

        a)      Employee will be entitled to fifty percent (50%) of his current
                compensation payable in six equal monthly installments,
                commencing one month after the termination date.

        b)      All outstanding vested options as of this date shall remain
                exercisable for a period of one year after termination date.

        c)      In addition, as of the termination date, Employee shall be
                entitled to receive any unpaid salary and accrued vacation pay.

        d)      For purposes of section 2 and 3 of this Agreement, "current
                compensation" shall mean an amount equal to the annual base
                salary for the year in which the termination occurs plus the
                amount of any bonus payable to Employee during that year.

4)      No severance payment will be made under paragraphs 2 or 3 if termination
        occurs, for any reason, during the first ninety (90) days of employment.

5)      CONFIDENTIAL INFORMATION. Employee shall continue to maintain the
        confidentiality of all confidential and proprietary information of the
        Corporation and shall continue to comply with the terms and conditions
        of the Confidentiality Agreement(s) between Employee and Corporation.

6)      NON-DISPARAGEMENT. Employee agrees not to disparage the Corporation or
        any of its officers, directors, employees, products, vendors or
        customers.

7)      RELEASE OF CLAIMS. Both parties agree that the foregoing consideration
        represents settlement in full of all outstanding obligations owed by
        Corporation to the Employee. Employee and his respective heirs,
        executors, assigns and agents hereby fully and forever releases
        Corporation and its officers, directors, employees, assigns and agents
        from any claim, duty, obligation or cause of action relating to any
        matters, known or unknown, arising from any omissions, acts or facts
        that have occurred up until the termination date, including without
        limitation:

        a)      Any claims relating to Employee's employment relationship with
                the Corporation.

        b)      Any claims relating to Employee's receipt of options and/or
                purchase or sales of shares of stock of the Corporation.

        c)      Any claims for violation of state, federal or municipal law.

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<PAGE>

8)      CONFIDENTIALITY. The parties agree to use their best efforts to maintain
        in confidence the existence, contents and terms of this Agreement,
        except as disclosure may be required by law.

9)      TAX CONSEQUENCES. The Corporation makes no representations or warranties
        with respect to the tax consequences of any consideration received by
        Employee under the terms of this Agreement. Employee agrees that he is
        solely responsible for payment, if any, of local, state or federal taxes
        on all consideration received. Employee further agrees to indemnify the
        Corporation for any claims due to his failure to pay any such taxes.

10)     ENTIRE AGREEMENT. This Agreement represents the entire agreement and
        understanding between the Corporation and Employee concerning Employee's
        relationships with the Corporation and supersedes any prior written or
        oral agreements concerning Employee relationship with and compensation
        from the Corporation and may not be changed except in written form
        signed by both parties.

11)     GOVERNING LAW: JURISDICTION. This Agreement, shall be governed by the
        laws of the State of California. Any disputes shall be resolved by
        binding arbitration by JAMSENDISPUTE in Santa Clara County, to which
        binding arbitration both parties consent.

12)     NO LEGAL REPRESENTATION. Employee is advised to seek his own legal
        advice in this matter and acknowledges that Venture Law Group and Lionel
        M. Allan are acting solely as counsel for the Corporation and not for
        Employee.

IN WITNESS WHEREOF, the parties have executed this Agreement, as of the date
first written above.

Catalyst Semiconductor, Inc.

By: /s/ Radu Vanco                                 /s/ Gelu Voicu
   --------------------------------     ----------------------------------------
    Radu Vanco                               In his individual capacity
    President and CEO                                Gelu Voicu

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