Document:

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                                                                   EXHIBIT 10.51

                    AMENDMENT TO JOINT DEVELOPMENT AGREEMENT

        This Amendment ("Amendment") to the parties' Joint Development Agreement
("Agreement") dated December 14, 2001, is entered into and effective as of this
18th day of January 2003, by and between ESS Technology Inc., ("ESS"), a
California corporation having a registered office at 48401 Fremont Blvd.,
Fremont, CA 94538, and *** ("Counterparty*"), a corporation organized under the
laws of ***, having a principal place of business at ***.

        WHEREAS, the parties have entered into the Joint Development Agreement;
and

        WHEREAS; the parties desire to amend and clarify the terms of the Joint
Development Agreement as set forth herein.

        NOW, THEREFORE, in consideration of the mutual promises contained herein
and for good and valuable consideration, the receipt and sufficiency of which is
hereby acknowledged, the parties hereby agree as follows:

        1. Section 1 "Definitions" shall be amended to include the following
defined terms:

        "Assembly Facility" shall mean ***, or such other assembly, packaging,
        and testing facility as has been agreed to by the parties.

        "Foundry" shall mean *** or such other foundry as has been agreed to by
        the parties.

        2. Section 4 "Manufacturing, Marketing, and Distribution" and Section 5
        "Accounting; Audit; Payment" shall be amended to include the following
        terms:

        *** shall issue a Combined Product Purchase Order ("P.O.") to the
        Foundry, and *** shall be responsible for costs of fabrication. Once
        fabricated, the Foundry will drop-ship the wafers to the designated
        Assembly Facility.

        *** shall issue a P.O. to *** for the purchase of all the wafers
        fabricated from the Foundry.

        *** shall issue a P.O. to the Assembly Facility for the wafer sort, and
        shall be responsible for the costs thereof.

        *** shall then issue a P.O. to the Assembly facility for packaging and
        testing, and will be responsible of the costs thereof.

        *** shall then issue a P.O. to *** for the Combined Product finished
        goods.

        ESS and Counterparty* agree that the manufacturing costs of either wafer
        fabrication, sorting, packaging or test shall be ***. If either party
        receives any rebates, discounts,

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* All references to the counterparty on this page have been replaced with the
term "Counterparty*." Confidential treatment has been requested with respect to
the replaced reference.

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

<PAGE>

        commission or credit from any Product-related manufacturer, each party
        shall be obligated to disclose it (to be treated as ***) to the other
        party immediately.

        ESS and Counterparty* agree to meet on a quarterly basis to reconcile
        accounting and payments due. All accounting for this manufacturing
        venture shall be *** in accordance with Section 5 of the Joint
        Development Agreement.

        *** shall provide *** with ***-month wafer rolling forecasts, and
        provide firm wafer P.O. information to ***. *** agree that *** will
        invoice or/and ship *** all the finished Combined Products within 30
        days of ***'s receipt of these finished Combined Product from the
        testing manufacture.

        The parties agree to work together in developing testing programs for
        the Combined Products, do yield improvement, and resolve any quality
        issues.

        Counterparty* is authorized to sell Combined Products, in die or
        finished-goods form, only to ESS.

        ESS is authorized to sell Combined Products' wafers only to
        Counterparty*. Unless with Counterparty*'s authorized written consent,
        ESS or any third party can not place any Combined Product's P.O. to any
        packaging or testing manufacturer.

        If required, either party will provide direct assistance to the Assembly
        Facility for the assembly, packaging, and testing of the Combined
        Products. In the event Counterparty* decides not to provide the package
        and test Combined Products service, ESS may elect to manufacture the
        Combined Products either itself or with Counterparty*'s prior written
        consent, through a third party. Sales of such Products shall only be
        together with, or for use with ESS/Counterparty* Combined Products.
        Whether such manufacture is by ESS or by a third party, ESS shall pay
        Counterparty* profit shares according to the formula stipulated in the
        Agreement.

        Payment terms are *** for all sales of inventory between the parties.

        3. Exhibit A "Specification" "2. Features of each Combined Product"
shall be amended to include the following terms:

        The Basic Features of the Combined Product shall be judged and
        determined by and from the market mainstream basic
        specification/features products manufactured by major competitors.

        Basic Features Combined Product Sold Ratio=***.

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* All references to the counterparty on this page have been replaced with the
term "Counterparty*." Confidential treatment has been requested with respect to
the replaced reference.

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

        ESS and Counterparty* agree that the Basic Features Combined Product
        Sold Ratio shall not be less than ***%. If the above Ratio is less than
        ***%, then both parties agree to treat the *** as *** for profit sharing
        calculation purpose; if the above two models' cumulated Ratio is still
        less than ***%, then the *** will be treated as *** too. This rule shall
        apply until the cumulated Ratio is more than ***%.

        4. This Amendment hereby only amends the Joint Development Agreement
Sections 1, 4, 5, and Exhibit A (2) as specified in the above, and is deemed
fully incorporated therein by reference as though set forth in such Agreement in
full. All terms used herein, except where otherwise designated, shall have the
same meanings as they have in the Agreement. In the event of any conflict
between the provisions of this Amendment and the provisions of the Agreement,
the provisions of this Amendment shall prevail.

IN WITNESS WHEREOF, the parties have caused this Amendment to be as of the
Effective Date.

        On behalf of                               On behalf of
        ESS Technology Inc.                        *** Corporation

By:     /s/ Fred S. L. Chan                 By:    /s/ ***
   -----------------------------               ------------------------------

Name:   Fred S. L. Chan                            Name:  ***

Title:  Chairman                                   Title:  President

Date:   18 Jan 2003                                Date:  Jan. 18, 2003

      Both parties also agree to delete the Agreement Exhibit C (4)'s ***.

                                FSLC     ***

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* All references to the counterparty on this page have been replaced with the
term "Counterparty*." Confidential treatment has been requested with respect to
the replaced reference.

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -3-<PAGE>
                                                                   Exhibit 10.18

                         SEVERANCE AGREEMENT AND RELEASE

                                    RECITALS

        This Severance Agreement and Release ("Agreement") is made by and
between Jan Hughes ("Employee") and Argonaut Technologies, Inc. ("Company"),
collectively referred to as the ("Parties"):

        WHEREAS, Employee was employed by the Company;

        WHEREAS, the Company and Employee have entered into an Employee
Proprietary Information Agreement (the "Confidentiality Agreement");

        WHEREAS, the Company and Employee have entered into a Stock Option
Agreement dated November 12, 1997, October 21, 1999, April 18, 2001 and January
30, 2002 granting Employee the option to purchase shares of the Company's common
stock subject to the terms and conditions of the Company's 1995 and 2000 Stock
Option Plans and the Stock Option Agreement (the "Stock Agreements");

        WHEREAS, the Employee's position as Senior Vice President and Chief
Technology Officer has been eliminated and the Employee has been terminated
effective December 31, 2002 (The "Termination Date").

        WHEREAS, the Parties, and each of them, wish to resolve any and all
disputes, claims, complaints, grievances, charges, actions, petitions and
demands that the Employee may have against the Company as defined herein,
including, but not limited to, any and all claims arising or in any way related
to Employee's employment with, or separation from, the Company;

        NOW THEREFORE, in consideration of the promises made herein, the Parties
hereby agree as follows:

                                    COVENANTS

1.Consideration.

        (a) Lump Sum Payment. As consideration for the promises made by Employee
in this Agreement, the Company agrees to pay Employee a lump sum equivalent to 6
months of Employee's current salary. The parties agree that this payment is
consideration to Employee above and beyond anything of value to which Employee
is already entitled.

        (b) Payment. The Company will tender the lump sum payment in this
section to Employee by delivering a check for $98,747.16, less applicable
withholding, made payable to Employee, within ten (10) business days from the
Effective Date of this Agreement. This check shall be delivered to the last
known address Employee has on file with the Company. The parties
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agree that this payment is consideration to Employee above and beyond anything
of value (salary, wages, accrued Personal Time Off (PTO), floating holidays, and
any and all other benefits due to Employee) to which Employee is already
entitled.

        (c) Stock. The Parties agree that for purposes of determining the number
of shares of the Company's common stock which Employee is entitled to purchase
from the Company, pursuant to the exercise of outstanding options, the Employee
will be considered to have vested only up to the Termination Date. Employee
acknowledges that as of the Termination Date, he will have vested in 50,564
options and no more. The exercise of any stock options shall continue to be
subject to the terms and conditions of the Stock Agreements, however, the
Employee shall have up to 6 months to exercise any vested stock options after
the Termination Date

        (d) Benefits. Employee shall have the right to convert his/her health
insurance benefits to individual coverage pursuant to COBRA. Upon execution of
this agreement by both parties, the Company will pay the first six months of
medical benefit COBRA for the Employee and his dependents and three months of
participation with a designated outplacement service for Employee. Details will
be addressed under separate cover.

      2. Confidential Information. Employee shall continue to maintain the
confidentiality of all confidential and proprietary information of the Company
and shall continue to comply with the terms and conditions of the
Confidentiality Agreement between Employee and the Company. Employee shall
return all of the Company's property and confidential and proprietary
information in his/her possession to the Company on the Effective Date of this
Agreement.

      3. Payment of Salary. Employee acknowledges and represents that the
Company has paid all salary, wages, accrued Personal Time Off (PTO), floating
holidays, and any and all other benefits due to Employee once the above noted
payments and benefits are received, with the exception of earned 2002 Variable
Compensation as detailed in the 2002 Executive Compensation Plan you received
earlier this year. Your personal objectives will be measured and documented as
of December 31, 2002. The personal objectives for 2002 are:

-     Continue to ensure that the Pfizer and GSK projects are proceeding as
      planned

-     Work with Gordon Tredger, Argonaut's Vice President of Instrumentation and
      Integration, to successfully transfer the management of these projects

-     Successfully transfer these important customer relationships to the
      appropriate person(s) within Argonaut, so there is no impact on Argonaut's
      contract research agreements and specifically the funding of these
      projects.

Calculation of any earned variable compensation will be completed in the first
quarter of 2003 and the Employee will be paid any cash due in February, 2003.

      4. Release of Claims. Employee agrees that the foregoing consideration
represents settlement in full of all outstanding obligations owed to Employee by
the Company. Employee, on

                                      -2-
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his/her own behalf, and on behalf of his/her respective heirs, family members,
executors, and assigns, hereby fully and forever releases the Company and its
officers, directors, employees, investors, shareholders, administrators,
affiliates, divisions, subsidiaries, predecessor and successor corporations, and
assigns, from, and agree not to sue concerning, any claim, duty, obligation or
cause of action relating to any matters of any kind, whether presently known or
unknown, suspected or unsuspected, that Employee may possess arising from any
omissions, acts or facts that have occurred up until and including the Effective
Date of this Agreement including, without limitation:

        (a) any and all claims relating to or arising from Employee's employment
relationship with the Company and the termination of that relationship;

        (b) any and all claims relating to, or arising from, Employee's right to
purchase, or actual purchase of shares of stock of the Company, including,
without limitation, any claims for fraud, misrepresentation, breach of fiduciary
duty, breach of duty under applicable state corporate law, and securities fraud
under any state or federal law;

        (c) any and all claims under the law of any jurisdiction including, but
not limited to, wrongful discharge of employment; constructive discharge from
employment; termination in violation of public policy; discrimination; breach of
contract, both express and implied; breach of a covenant of good faith and fair
dealing, both express and implied; promissory estoppel; negligent or intentional
infliction of emotional distress; negligent or intentional misrepresentation;
negligent or intentional interference with contract or prospective economic
advantage; unfair business practices; defamation; libel; slander; negligence;
personal injury; assault; battery; invasion of privacy; false imprisonment; and
conversion;

        (d) any and all claims for violation of any federal, state or municipal
statute, including, but not limited to, Title VII of the Civil Rights Act of
1964, the Civil Rights Act of 1991, the Age Discrimination in Employment Act of
1967, the Americans with Disabilities Act of 1990, the Fair Labor Standards Act,
the Employee Retirement Income Security Act of 1974, The Worker Adjustment and
Retraining Notification Act, Older Workers Benefit Protection Act; the
California Fair Employment and Housing Act, and Labor Code section 201, et seq.
and section 970, et seq.;

        (e) any and all claims for violation of the federal, or any state,
constitution;

        (f) any and all claims arising out of any other laws and regulations
relating to employment or employment discrimination;

        (g) any claim for any loss, cost, damage, or expense arising out of any
dispute over the non-withholding or other tax treatment of any of the proceeds
received by Employee as a result of this Agreement; and

        (h) any and all claims for attorneys' fees and costs.

                                      -3-
<PAGE>
        The Company and Employee agree that the release set forth in this
section shall be and remain in effect in all respects as a complete general
release as to the matters released. This release does not extend to any
obligations incurred under this Agreement.

        Employee acknowledges and agrees that any breach of any provision of
this Agreement shall constitute a material breach of this Agreement and shall
entitle the Company immediately to recover the severance benefits provided to
Employee under this Agreement, to the extent permitted by law.

      5. Acknowledgement of Waiver of Claims Under ADEA. Employee acknowledges
that he/she is waiving and releasing any rights he/she may have under the Age
Discrimination in Employment Act of 1967 ("ADEA") and that this waiver and
release is knowing and voluntary. Employee and the Company agree that this
waiver and release does not apply to any rights or claims that may arise under
ADEA after the Effective Date of this Agreement. Employee acknowledges that the
consideration given for this waiver and release Agreement is in addition to
anything of value to which Employee was already entitled. Employee further
acknowledges that he/she has been advised by this writing that:

        (a) he/she should consult with an attorney prior to executing this
Agreement;

        (b) he/she has up to forty-five (45) days within which to consider this
Agreement;

        (c) he/she has been advised in writing by the Company of the class,
unit, or group of individuals affected by the reduction in force, and the job
titles and ages of all individuals who were and were not affected;

        (d) he/she has seven (7) days following his/her execution of this
Agreement to revoke the Agreement;

        (e) this Agreement shall not be effective until the revocation period
has expired; and

        (f) nothing in this Agreement prevents or precludes Employee from
challenging or seeking a determination in good faith of the validity of this
waiver under the ADEA, nor does it impose any condition precedent, penalties or
costs for doing so, unless specifically authorized by federal law.

      6. Civil Code Section 1542. The Parties represent that they are not aware
of any claim by either of them other than the claims that are released by this
Agreement. Employee and the Company acknowledge that they have been advised by
legal counsel and are familiar with the provisions of California Civil Code
Section 1542, which provides as follows:

                                      -4-
<PAGE>
               A GENERAL RELEASE DOES NOT EXTEND TO CLAIMS WHICH THE CREDITOR
               DOES NOT KNOW OR SUSPECT TO EXIST IN HIS FAVOR AT THE TIME OF
               EXECUTING THE RELEASE, WHICH IF KNOWN BY HIM MUST HAVE MATERIALLY
               AFFECTED HIS SETTLEMENT WITH THE DEBTOR.

      Employee and the Company, being aware of said code section, agree to
expressly waive any rights they may have thereunder, as well as under any other
statute or common law principles of similar effect.

      7. No Pending or Future Lawsuits. Employee represents that he/she has no
lawsuits, claims, or actions pending in his/her name, or on behalf of any other
person or entity, against the Company or any other person or entity referred to
herein. Employee also represents that he/she does not intend to bring any claims
on his/her own behalf or on behalf of any other person or entity against the
Company or any other person or entity referred to herein.

      8. Confidentiality. The Parties acknowledge that Employee's agreement to
keep the terms and conditions of this Agreement confidential was a material
factor on which all parties relied in entering into this Agreement. Employee
hereto agrees to use his/her best efforts to maintain in confidence the
existence of this Agreement, the contents and terms of this Agreement, the
consideration for this Agreement, and any allegations relating to the Company or
his/her employment with the Company except as otherwise provided for in this
Agreement (hereinafter collectively referred to as "Settlement Information").
Employee agrees to take every reasonable precaution to prevent disclosure of any
Settlement Information to third parties, and agrees that there will be no
publicity, directly or indirectly, concerning any Settlement Information.
Employee agrees to take every precaution to disclose Settlement Information only
to those attorneys, accountants, governmental entities, and family members who
have a reasonable need to know of such Settlement Information. The Parties agree
that an enforcement action shall be arbitrated pursuant to this Agreement and
that, if Company proves that Employee breached this Confidentiality provision,
it shall be entitled to an award of its costs spent enforcing this provision,
including all reasonable attorneys' fees associated with the enforcement action,
without regard to whether the Company can establish actual damages from the
breach by Employee.

      9. No Cooperation. Employee agrees he/she will not act in any manner that
might damage the business of the Company. Employee agrees that he will not
counsel or assist any attorneys or their clients in the presentation or
prosecution of any disputes, differences, grievances, claims, charges, or
complaints by any third party against the Company and/or any officer, director,
employee, agent, representative, shareholder or attorney of the Company, unless
under a subpoena or other court order to do so. Employee further agrees both to
immediately notify the Company upon receipt of any court order, subpoena, or any
legal discovery device that seeks or might require the disclosure or production
of the existence or terms of this Agreement, and to furnish, within three (3)
business days of its receipt, a copy of such subpoena or legal discovery device
to the Company.

                                      -5-
<PAGE>
      10. Non-Disparagement. Employee agrees to refrain from any defamation,
libel or slander of the Company or tortious interference with the contracts and
relationships of the Company. All inquiries by potential future employers of
Employee will be directed to Human Resources. Upon inquiry, the Company shall
only state the following: Employee 's last position and dates of employment.

      11. Non-Solicitation. Employee agrees that for a period of twelve (12)
months immediately following the Effective Date of this Agreement, Employee
shall not either directly or indirectly solicit, induce, recruit or encourage
any of the Company's employees to leave their employment, or take away such
employees, or attempt to solicit, induce, recruit, encourage, take away or hire
employees of the Company, either for him/herself or any other person or entity.

      12. No Admission of Liability. The Parties understand and acknowledge that
this Agreement constitutes a compromise and settlement of disputed claims. No
action taken by the Parties hereto, or either of them, either previously or in
connection with this Agreement shall be deemed or construed to be: (a) an
admission of the truth or falsity of any claims heretofore made or (b) an
acknowledgment or admission by either party of any fault or liability whatsoever
to the other party or to any third party.

      13. Costs. The Parties shall each bear their own costs, expert fees,
attorneys' fees and other fees incurred in connection with this Agreement. 14.
Indemnification. Employee agreed to indemnify and hold harmless the Company from
and against any and all loss, costs, damages or expenses, including, without
limitation, attorneys' fees or expenses incurred by the Company arising out of
the breach of this Agreement by Employee, or from any false representation made
herein by Employee, or from any action or proceeding which may be commenced,
prosecuted or threatened by Employee or for Employee's benefit, upon Employee's
initiative, or with Employee's aid or approval, contrary to the provisions of
this Agreement. Employee further agrees that in any such action or proceeding,
this Agreement may be pled by the Company as a complete defense, or may be
asserted by way of counterclaim or cross-claim.

      15. Arbitration. The Parties agree that any and all disputes arising out
of the terms of this Agreement, their interpretation, and any of the matters
herein released, shall be subject to binding arbitration in San Mateo County,
California before the American Arbitration Association under its Employment
Dispute Resolution Rules, or by a judge to be mutually agreed upon. The Parties
agree that the prevailing party in any arbitration shall be entitled to
injunctive relief in any court of competent jurisdiction to enforce the
arbitration award. The Parties agree that the prevailing party in any
arbitration shall be awarded its reasonable attorneys' fees and costs. THE
PARTIES HEREBY AGREE TO WAIVE THEIR RIGHT TO HAVE ANY DISPUTE BETWEEN THEM
RESOLVED IN A COURT OF LAW BY A JUDGE OR JURY. This section will not prevent
either party from seeking injunctive relief (or any other provisional remedy)
from any court having jurisdiction over the parties and the subject matter of

                                      -6-
<PAGE>
their dispute relating to Employee's obligations under this Agreement and the
agreements incorporated herein by reference.

      16. Authority. The Company represents and warrants that the undersigned
has the authority to act on behalf of the Company and to bind the Company and
all who may claim through it to the terms and conditions of this Agreement.
Employee represents and warrants that he/she has the capacity to act on his/her
own behalf and on behalf of all who might claim through him/her to bind them to
the terms and conditions of this Agreement. Each party warrants and represents
that there are no liens or claims of lien or assignments in law or equity or
otherwise of or against any of the claims or causes of action released herein.

      17. No Representations. Each party represents that it has had the
opportunity to consult with an attorney, and has carefully read and understands
the scope and effect of the provisions of this Agreement. Neither party has
relied upon any representations or statements made by the other party hereto
which are not specifically set forth in this Agreement.

      18. Severability. In the event that any provision hereof becomes or is
declared by a court of competent jurisdiction to be illegal, unenforceable or
void, this Agreement shall continue in full force and effect without said
provision so long as the remaining provisions remain intelligible and continue
to reflect the original intent of the Parties. 19. Entire Agreement. This
Agreement, and the agreements incorporated herein by reference to the extent
they are consistent with this Agreement, constitute the entire agreement and
understanding between the Parties concerning the subject matter of this
Agreement and all prior representations, understandings, and agreements
concerning the subject matter of this Agreement have been merged into this
Agreement.

      20. No Waiver. The failure of any party to insist upon the performance of
any of the terms and conditions in this Agreement, or the failure to prosecute
any breach of any of the terms and conditions of this Agreement, shall not be
construed thereafter as a waiver of any such terms or conditions. This entire
Agreement shall remain in full force and effect as if no such forbearance or
failure of performance had occurred.

      21. No Oral Modification. Any modification or amendment of this Agreement,
or additional obligation assumed by either party in connection with this
Agreement, shall be effective only if placed in writing and signed by both
Parties or by authorized representatives of each party. No provision of this
Agreement can be changed, altered, modified, or waived except by an executed
writing by the Parties.

      22. Governing Law. This Agreement shall be deemed to have been executed
and delivered within the State of California, and it shall be construed,
interpreted, governed, and enforced in accordance with the laws of the State of
California, without regard to choice of law principles.

      23. Attorneys' Fees. In the event that either Party brings an action to
enforce or effect its rights under this Agreement, the prevailing party shall be
entitled to recover its costs and expenses,

                                      -7-
<PAGE>
including the costs of mediation, arbitration, litigation, court fees, plus
reasonable attorneys' fees, incurred in connection with such an action.

      24. Effective Date. This Agreement is effective after it has been signed
by both parties and after eight (8) days have passed since Employee has signed
the Agreement (the "Effective Date"), unless revoked by Employee within seven
(7) days after the date the Agreement was signed by Employee.

      25. Counterparts. This Agreement may be executed in counterparts, and each
counterpart shall have the same force and effect as an original and shall
constitute an effective, binding agreement on the part of each of the
undersigned.

      26. Voluntary Execution of Agreement. This Agreement is executed
voluntarily and without any duress or undue influence on the part or behalf of
the Parties hereto, with the full intent of releasing all claims. The Parties
acknowledge that:

            (a) They have read this Agreement;

            (b) They have been represented in the preparation, negotiation, and
      execution of this Agreement by legal counsel of their own choice or that
      they have voluntarily declined to seek such counsel;

            (c) They understand the terms and consequences of this Agreement and
      of the releases it contains; and

            (d) They are fully aware of the legal and binding effect of this
      Agreement.

IN WITNESS WHEREOF, the Parties have executed this Agreement on the respective
dates set forth below.

                                            Argonaut Technologies, Inc.

Dated: 12/9/02                              By /s/ Lissa A. Goldenstein
      -----------------                     ------------------------------------
                                            Lissa A. Goldenstein
                                            President and CEO

                                            Jan Hughes, an individual

Dated: 12/9/02                               /s/ Jan Hughes
      -----------------                     ------------------------------------
                                            Jan Hughes

                                      -8-

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