<PAGE>

                                                                   EXHIBIT 10.21


                       EMPLOYEE STOCK PURCHASE AGREEMENT
                       ---------------------------------


     This Employee Stock Purchase Agreement (this "Agreement") is made as of
                                                   ---------
September 16, 1999 by and between Millitech Corporation, a Massachusetts
corporation (the "Company") and Mervyn FitzGerald ("Purchaser").
                  -------                           ---------

     WHEREAS, the Company desires to issue and Purchaser desires to purchase
Common Stock of the Company on the terms and conditions hereinafter set forth.

     NOW, THEREFORE, it is agreed between the parties as follows:

     1.   Purchaser hereby agrees to purchase from the Company, and the Company
agrees to sell to the Purchaser, 225,000 shares of its Common Stock for a
purchase price of $1.25 per share, payable in accordance with the terms of a
Promissory Note, dated as of September 16, 1999, from Purchaser to the Company a
form of which is attached as Exhibit A.  The closing hereunder shall occur at
                             ---------
the offices of the Company on the date of this Agreement or at such other time
and place as the parties may mutually agree.

     2.   All of the shares of the Company's Common Stock being purchased by
Purchaser pursuant to this Agreement (hereinafter sometimes collectively
referred to as the "Stock") shall be subject to the repurchase right (the
                    -----
"Repurchase Right") set forth in this Section 2.
 ----------------

          (a)  If the Purchaser shall cease to be employed by the Company, then
the Company may repurchase from Purchaser (or his personal representative, as
the case may be) all non-vested Stock at the purchase price per share set forth
in Section 1 (the "Repurchase Price") at any time within sixty (60) days after
the date Purchaser ceases to be so employed. For the purposes of this Agreement,
45,000 shares of Stock shall be deemed vested as of the date of this Agreement
and 45,000 shares of the Stock shall become vested each year on the anniversary
date of this Agreement. Upon (i) the completion of a merger or consolidation of
the Company with any other entity wherein the Company is not the surviving
entity, (ii) the sale of substantially all of the Company's assets to another
entity, or (iii) the sale or transfer of more than 50% of the outstanding
capital stock of the Company to an unrelated person or group of persons acting
collectively in one or a series of transactions, all non-vested Stock will be
immediately vested. All vested Stock shall be subject to the First Refusal right
set forth in Section 3.

          (b)  If the Purchaser:

               (i)   files a voluntary petition under any bankruptcy or
insolvency law or a petition for the appointment of a receiver or makes an
assignment for the benefit of creditors;

               (ii)  is subjected involuntarily to such a petition or assignment
or to an attachment or other legal or equitable interest with respect to his
shares of stock and such involuntary petition or assignment or attachment is not
discharged within 60 days after its date; or
<PAGE>

               (iii) is required to transfer his shares of stock by operation of
law (other than death of the Stockholder) or by order or decree of any court; or

               (iv)  shall die or become permanently disabled;

then the Company shall have the option, exercisable at any time during the
period of sixty (60) days after receiving notice thereof, to purchase all or any
portion of the non-vested Stock owned by the Purchaser (or his personal
representative, as the case may be) for the Repurchase Price and upon the terms
as set forth in Section 4. If within sixty (60) days after receipt of the
notice, the Company does not elect to purchase all or any portion of the non-
vested Stock then the Repurchase Right shall cease with respect to such shares.
Failure of the Company to elect to purchase said shares under this Section shall
not affect the right to purchase the same shares under Section 3(a) in the event
of a proposed sale, assignment, transfer, exchange, pledge or other disposition
by or to any receiver, petitioner, assignee, transferee or other person
obtaining an interest in said shares.

          (c)  Nothing in this Agreement shall affect in any manner whatsoever
the right or power of the Company, or a parent or subsidiary of the Company, to
terminate Purchaser's employment, for any reason, with or without cause.

     3.   (a)  Purchaser shall not sell or otherwise transfer any shares of
Stock unless prior to any sale or other transfer thereof, Purchaser (or his
personal representative, as the case may be) shall provide the Company with
written notice, in the manner provided in Section 12, describing the number of
shares of Stock intended to be sold or transferred, the price and the general
terms of the proposed sale or transfer.

          (b)  The Company shall have the right (the "First Refusal Right") at
any time within sixty (60) days after the notice required by Section 3(a) to
purchase from Purchaser (or his personal representative, as the case may be) up
to but not exceeding the number of shares of the Stock specified in, and at the
price (the "First Refusal Price") and upon the general terms specified in such
notice.

          (c)  If the First Refusal Right is not exercised with respect to some
or all the shares of the Stock specified in the notice required by Section 3(a),
then for a period of 120 days, Purchaser (or his personal representative, as the
case may be) shall be free to sell, or otherwise transfer up to but not
exceeding the number of shares of the Stock specified in the notice required by
Section 3(a), minus the number of shares of the Stock with respect to which the
First Refusal Right was exercised, at a price and upon general terms no more
favorable to purchasers or transferees thereof than specified in the notice
required by Section 3(a).

          (d)  In the event that any shares of the Stock which are free to be
sold or otherwise transferred under the terms of Section 3(c) are not sold or
otherwise transferred within said 120-day period, such shares of the Stock shall
again be subject to the First Refusal Right and Purchaser (or his personal
representative, as the case may be) shall comply with all the
<PAGE>

provisions of this Section 3 prior to selling or otherwise transferring any such
shares of the Stock.

          (e)  Failure to exercise the First Refusal Right with respect to any
shares of the Stock shall not constitute a waiver of the First Refusal Right
with respect to any other shares of the Stock.

          (f)  The First Refusal Right shall continue after the death or
termination of the employment of Purchaser with the Company for any reason, or
no reason, and shall terminate only upon the closing of an underwritten public
offering pursuant to an effective registration statement under the Securities
Act of 1933, as amended, covering the offer and sale of shares of Common Stock
of the Company to the public at a public offering price of not less than $4.50
per share (as adjusted for stock splits, stock dividends, distributions or
subdivisions) and resulting in gross proceeds to the Company of not less than
Fifteen Million Dollars ($15,000,000).

     4.   The Repurchase Right and the First Refusal Right shall be exercised by
written notice signed by an officer of the Company and delivered or mailed as
provided in Section 12. The Repurchase Price and the First Refusal Price shall
be payable first in cancellation of all or a portion of any outstanding
indebtedness and interest thereon of Purchaser to the Company represented by the
Note and then in cash (by check) or both.

     5.   The Company may assign its rights under Sections 2 and 3.

     6.   If, from time to time during the term of the Repurchase Right or the
First Refusal Right:

          (a)  There is any stock dividend or liquidating dividend of cash
and/or property, stock split or other change in the character or amount of any
of the outstanding securities of the Company; or

          (b)  There is any consolidation or merger where the Company is the
survivor unless such consolidation or merger is with a publicly-owned
corporation and the aggregate market value of the securities or other property
the stockholders of the Company receive is in excess of Fifteen Million Dollars
($15,000,000)].

then, in such event, any and all new, substituted or additional securities or
other property (other than cash) to which Purchaser is entitled by reason of his
ownership of Stock shall be immediately subject to the Repurchase Right or the
First Refusal Right, as the case may be, and be included in the word "Stock" for
all purposes of the Repurchase Right and the First Refusal Right with the same
force and effect as the shares of Stock subject to the Repurchase Right and the
First Refusal Right under the terms of Sections 2 and 3. While the total
Repurchase Price shall remain the same after each such event, the Repurchase
Price per share of Stock upon exercise of the Repurchase Right shall be
appropriately adjusted. Stock acquired as provided in clauses (a) or (b) above
shall be deemed to have been acquired at the time of acquisition of the Stock on
which such Stock was distributed.
<PAGE>

     7.   All certificates representing any shares of Stock subject to the
provisions of this Agreement shall have endorsed thereon the following legends:

          (a)  "Any disposition of any interest in the securities represented by
this certificate is subject to restrictions, and the securities represented by
this certificate are subject to a repurchase right and a first refusal right
contained in a certain agreement between the record holder hereof and the
corporation, a copy of which will be mailed to any holder of this certificate
without charge within 5 days of receipt by the corporation of a written request
therefor."

          (b)  Any legend required to be placed thereon by federal or state
securities laws.

     8.   Purchaser acknowledges that Purchaser is aware that the Stock to be
issued to him by the Company pursuant to this Agreement has not been registered
under the Securities Act of 1933, as amended.  In this connection, Purchaser
warrants and represents to the Company as follows:

          (a)  Purchaser is purchasing the Stock solely for Purchaser's own
account for investment and not with a view to or for sale or distribution of the
Stock or any portion thereof and not with any present intention of selling,
offering to sell or otherwise disposing of or distributing the Stock or any
portion thereof. Purchaser also represents that the entire legal and beneficial
interest of the Stock Purchaser is purchasing is being purchased for, and will
be held for the account of, the Purchaser only and neither in whole nor in part
for any other person.

          (b)  Purchaser has heretofore discussed the Company and its plans,
operations and financial condition with its officers and that Purchaser has
heretofore received all such information as Purchaser deems necessary and
appropriate to enable Purchaser to evaluate the financial risk inherent in
making an investment in the Stock of the Company and Purchaser further
represents and warrants that Purchaser has received satisfactory and complete
information concerning the business and financial condition of the Company in
response to all inquiries in respect thereof.

          (c)  Purchaser realizes that the purchase of the Stock will be a
highly speculative investment and that Purchaser is able, without impairing
Purchaser's financial condition, to hold the Stock for an indefinite period of
time and to suffer a complete loss on the investment.

          (d)  The Company has disclosed to Purchaser in writing:

               (i)  the sale of the Stock which it is purchasing has not been
registered under the Securities Act of 1933, as amended (the "Act"), and the
Stock must be held indefinitely unless a transfer of them is subsequently
registered under the Act or an exemption from such registration is available;
<PAGE>

               (ii)  the share certificate representing the Stock will be
stamped with the legends restricting transfer specified in this Agreement
between the Company and the Purchaser; and

               (iii) the Company will make a notation in its records of the
aforementioned restrictions on transfer and legends.

          (e)  Purchaser understands that the Stock are restricted securities
within the meaning of Rule 144 promulgated under the Act; that the exemption
from registration under Rule 144 will not be available in any event for at least
one year from the date of sale of the Stock to Purchaser, and even then will not
be available unless (i) a public trading market then exists for the Stock of the
Company, (ii) adequate current public information concerning the Company is then
available to the public, (iii) Purchaser has been the beneficial owner and
Purchaser has paid the full purchase price for the Stock at least one year prior
to the sale, and (iv) other terms and conditions of Rule 144 are complied with;
and that any sale of the Stock may be made by it only in limited amounts in
accordance with such terms and conditions, as amended from time to time.

          (f)  Without in any way limiting its representations set forth above,
Purchaser further agrees that Purchaser shall in no event make any disposition
of all or any portion of the Stock which Purchaser is purchasing unless and
until:

               (i)   There is then in effect a Registration Statement under the
Act covering such proposed disposition and such disposition is made in
accordance with said Registration Statement; or

               (ii)  (A) Purchaser shall have notified the Company of the
proposed disposition and shall have furnished the Company with a detailed
statement of the circumstances surrounding the proposed disposition, (B)
Purchaser shall have furnished the Company with an opinion of counsel to the
effect that such disposition will not require registration of such shares under
the Act, and (C) such opinion of counsel shall have been concurred in by counsel
for the Company and the Company shall have advised Purchaser of such
concurrence.

     9.   The Company shall not be required (a) to transfer on its books any
shares of Stock of the Company which shall have been sold or transferred in
violation of any of the provisions set forth in this Agreement or (ii) to treat
as owner of such shares or to accord the right to vote as such owner or to pay
dividends to any transferee to whom such shares shall have been so transferred.
In the event of a sale of Stock by Purchaser pursuant to Section 3(c), Purchaser
shall furnish to the Company proof that such sale was made in compliance with
the provisions of Section 3(c) as to price and general terms of such sale.

     10.  Subject to the provisions of this Agreement, Purchaser shall, during
the term of this Agreement, exercise all rights and privileges of a shareholder
of the Company with respect to the Stock.
<PAGE>

     11.  The parties agree to execute such further instruments and to take such
further action as may reasonably be necessary to carry out the intent of this
Agreement.

[In addition, Purchaser shall execute and deliver to the Company the Stock
Assignment Separate from Certificate attached as Exhibit B and the Joint Escrow
                                                 ---------
Instructions attached as Exhibit C.]
                         ---------

     12.  Any notice required or permitted hereunder shall be given in writing
and shall be deemed effectively given upon personal delivery or upon deposit in
the United States Post Office, by certified mail with postage and fees prepaid,
addressed to the other party at his address hereinafter shown below his
signature or at such other address as such party may designate by ten days'
advance written notice to the other party.

     13.  This Agreement shall inure to the benefit of the successors and
assigns of the Company and be binding upon Purchaser and its heirs, executors,
administrators, successors and assigns.

     14.  This Agreement shall be governed by and interpreted under the laws of
the Commonwealth of Massachusetts.

     15.  This Agreement may be executed simultaneously in any number of
counterparts, each of which shall be deemed to be an original, but all of which
together shall constitute one and the same instrument.

     IN WITNESS WHEREOF, the parties have executed this Agreement under seal as
of the day and year first above written.


                                   MILLITECH CORPORATION


                                   /s/ John L. Youngblood
                                   --------------------------------
                                   By:   John L. Youngblood
                                   Title: President

                                   PURCHASER:


                                   /s/ Mervyn FitzGerald
                                   --------------------------------
                                   Mervin Fitzgerald

                                   Address:

                                   6934 Rocky Top Circle
                                   Dallas, TX 75252
<PAGE>

                                   EXHIBIT A
                                      TO
                       EMPLOYEE STOCK PURCHASE AGREEMENT

                                   TERM NOTE

$281,250
                                              South Deerfield, Mass.
                                              September 16, 1999


     FOR VALUE RECEIVED, Mervyn FitzGerald, of 6934 Rocky Top Circle, Dallas, TX
(the "Borrower") promises to pay to the order of Millitech Corporation, a
Massachusetts corporation having its principal place of business at South
Deerfield, Massachusetts (the "Company"), or order, at the Company's offices,
the principal sum of Two Hundred Eighty-One Thousand Two Hundred Fifty and
00/100 DOLLARS ($281,250), in lawful money of the United States of America, with
interest on the unpaid balance hereof at the rates and in the manner hereafter
provided.

     The unpaid principal of this Note from time to time outstanding shall bear
interest, payable annually in arrears, computed on the basis of the actual
number of days elapsed over a year assumed to have 360 days, at a rate per annum
equal to 6.25%.

     Commencing on September 15, 2000 and continuing on the same day of each
succeeding year thereafter, the Borrower agrees to pay interest on this Note.
The entire indebtedness evidenced by this Note, if not earlier paid, shall be
due and payable on September 15, 2009.

     The occurrence of any one or more of the following events is an Event of
Default under this Note:

          (a)  Failure of the Borrower to pay, perform or observe any of its
obligations contained in (i) this Note, or (ii) the Employee Stock Purchase
Agreement dated as of the date of this Note (the "Agreement"), or (iii) any
other document delivered to the Company in connection with this Note; or

          (c)  The death of the Borrower or the involvement of the Borrower in
any financial difficulties as evidenced by

              (i)   his insolvency within the meaning of the Massachusetts
                    Uniform Commercial Code; or
              (ii)  an assignment for the benefit of his creditors; or
              (iii) the appointment of a receiver, trustee, custodian,
                    liquidator or conservator of his assets not vacated or set
                    aside within sixty (60) days; or
              (iv)  the commencement by him of proceedings under any federal or
                    state law
<PAGE>

                     relating to bankruptcy, insolvency or relief of debtors; or
               (v)   the commencement against him of proceedings under any
                     federal or state law relating to bankruptcy, insolvency or
                     relief of debtors if the proceedings are not dismissed
                     within sixty (60) days after the date on which commenced.

     If an Event of Default occurs the Company may, to the extent permitted by
law and without notice to the Borrower, declare the unpaid principal balance and
accrued interest to be due immediately without notice, presentment, demand,
protest or other notice of dishonor of any kind, all of which are expressly
waived. If the Company declares the unpaid principal balance and accrued
interest to be due the Company shall accept tender of any un-vested Stock as
payment at the rate of $1.25 per share. The Borrower agrees to pay all
reasonable costs, including but not limited to attorneys' fees, incurred by the
Company in connection with collecting or enforcing any obligation of the
Borrower to the Company. No course of dealing by the Company and no delay in
exercising any right under this Note will operate as a waiver by the Company of
its rights, and a waiver of a right on one occasion may not be construed as a
waiver of the right on a future occasion.

     While no Event of Default exists each payment under this Note will be
applied first to interest then due and then to principal.  When an Event of
Default exists any payments will be applied to interest and/or principal as
determined by the Company in its discretion.  The Borrower may, at any time and
without penalty, prepay any part or all of the unpaid principal balance of this
Note in multiples of $1,000.00.

     Whenever any installment of principal or interest due under this Note shall
not be paid within ten (10) days of its due date, the Borrower shall pay in
addition thereto as a late charge, five percent (5%) of the amount of such
installment.

     Any deposits or other sums at any time credited by or due from the Company
to the Borrower, any endorser or guarantor hereof, may at all times be held and
treated as collateral for the payment of this Note and any and all other
liabilities (direct or indirect, absolute or contingent, sole, joint or several,
secured or unsecured, due or to become due, now existing or hereafter arising)
of any such maker to the Company. The Company may apply or set-off such deposits
or other sums against such liabilities at any time.

     The Borrower and each guarantor, endorser or other person now or hereafter
liable for the payment of any of the indebtedness evidenced by this Note,
severally agrees, by making, guaranteeing or endorsing this Note or by making
any agreement to pay any of the indebtedness evidenced by this Note, to waive
presentment for payment, protest and demand, notice of protest, demand and of
dishonor and nonpayment of this Note, and consents, on one or more occasions,
without notice or further assent (a) to the substitution, exchange or release of
the collateral, if any, securing this Note or any part thereof at any time, (b)
to the acceptance or release by the holder or holders hereof at any time of any
additional collateral or security for or other guarantors of this Note, (c) to
the modification or amendment, at any time and from time to time, of this Note,
the Agreement or any instrument securing this Note at the request of any person
<PAGE>

liable hereon, (d) to the granting by the holder hereof of any extension of the
time for the performance of the agreements, covenants and conditions contained
in this Note, the Agreement or any other instrument securing this Note, at the
request of any person liable hereon, and (e) to any and all forbearances and
indulgences whatsoever. Such consent shall not alter nor diminish the liability
of any person.

     The Borrower agrees to pay all reasonable expenses or costs, including
attorneys' fees and costs of collection, which may be incurred by the Company in
connection with the enforcement of any obligations hereunder or representation
with respect to bankruptcy or insolvency proceedings.

     This Note is issued under and pursuant to the Agreement to which Agreement
reference is hereby made for a statement of such terms and the respective rights
of the Borrower and the holder of this Note, which Agreement is incorporated
herein by reference thereto.

     The Borrower agrees that the proceeds (net of 3/rd/ party commissions) from
the sale of the Stock subject to the Agreement will be applied to reduce the
principal of this Note.

     Executed as a sealed instrument as of the 16th day of September, 1999.



/s/ [ILLEGIBLE]                       /s/ Mervyn FitzGerald
------------------                    -------------------------
Witness                               Mervyn FitzGerald
<PAGE>

                                   EXHIBIT B
                                      TO
                       EMPLOYEE STOCK PURCHASE AGREEMENT
                       ---------------------------------

                  STOCK ASSIGNMENT SEPARATE FROM CERTIFICATE
                  ------------------------------------------


     FOR VALUE RECEIVED Mervyn FitzGerald hereby sells, assigns and transfers
unto _____________________________ (______) shares of Common Stock of Millitech
Corporation, a Massachusetts corporation, standing in the undersigned's name on
the books of said corporation represented by Certificate No. 217, and does
hereby irrevocably constitute and appoint David L. Renauld, Clerk of Millitech
Corporation, or his duly elected successor, attorney to transfer the said stock
on the books of the said corporation with full power of substitution in the
premises.


Dated:

                       Signature: /s/ Mervyn FitzGerald
                                  ----------------------------
                                  Mervyn FitzGerald
<PAGE>

                                   EXHIBIT C
                                      TO
                       EMPLOYEE STOCK PURCHASE AGREEMENT
                       ---------------------------------


                           JOINT ESCROW INSTRUCTIONS
                           -------------------------



                                          September 16, 1999


David L. Renauld, Clerk
Millitech Corporation
South Deerfield Research Park
P. O. Box 209
South Deerfield, MA 01373

Dear Sirs:

     As Escrow Agent for both Millitech Corporation, a Massachusetts corporation
(the "Corporation"), and Mervyn Fitzgerald ("Buyer"), you are hereby authorized
and directed to hold the documents delivered to you pursuant to the terms of
that certain Employee Stock Purchase Agreement (including the Note attached
thereto as Exhibit A) (the "Agreement"), dated as of September, 1999, to which a
copy of these Joint Escrow Instructions is attached as Exhibit C, in accordance
with the following instructions:

     1.   In the event the Corporation and/or any assignee of the Corporation
(referred to collectively for convenience as the "Corporation") shall elect to
exercise the Repurchase Right or the First Refusal Right set forth in the
Agreement, the Corporation shall give to Buyer and you a written notice
specifying the number of shares of stock to be purchased, the purchase price,
and the time for a closing thereunder at the principal office of the
Corporation. Buyer and the Corporation hereby irrevocably authorize and direct
you to close the transaction contemplated by such notice in accordance with the
terms of said notice.

     2.   At the closing, you are directed (a) to date the stock assignment
necessary for the transfer in question, (b) to fill in the number of shares
being transferred, and (c) to deliver same, together with the certificate
evidencing the shares of stock to be transferred to the Corporation against the
simultaneous delivery to you of the purchase price (by check) for the number of
shares of stock being purchased pursuant to the exercise of the Repurchase Right
or the First Refusal Right.
<PAGE>

     3.   In the event of a sale of stock by Buyer in compliance with the
provisions of the Agreement permitting such sale upon failure of the Corporation
to exercise the First Refusal Right with respect to such stock, the Corporation
and the Buyer shall give you written notice stating that satisfactory
arrangements have been made for application of the proceeds of such sale
pursuant to the Agreement and authorizing you to deliver the number of shares of
stock being transferred, together with the certificate evidencing the shares of
stock being transferred, in accordance with the terms of such written notice.

     4.   Buyer irrevocably authorizes the Corporation to deposit with you any
certificates evidencing shares of stock to be held by you hereunder and any
additions and substitutions to said shares as referred to in the Agreement.
Buyer does hereby irrevocably constitute and appoint you as his attorney-in-fact
and agent for the term of this escrow to execute with respect to such securities
all documents necessary or appropriate to make such securities negotiable and
complete any transaction contemplated in this Agreement, including but not
limited to any appropriate filing with state securities officials. Subject to
the provisions of this Section 4, Buyer shall exercise all rights and privileges
of a shareholder of the Corporation while the stock is held by you.

     5.   This escrow shall terminate upon termination of the Agreement in
accordance with the provisions of the Agreement or upon exercise in full of the
Repurchase Right or the First Refusal Right.

     6.   If at the time of termination of this escrow you should have in your
possession any documents, securities, or other property belonging to Buyer, you
shall deliver all of same to Buyer and shall be discharged of all further
obligations hereunder.

     7.   Your duties hereunder may be altered, amended, modified or revoked
only by a writing signed by all of the parties.

     8.   You shall be obligated only for the performance of such duties as are
specifically set forth in this Agreement and may rely and shall be protected in
relying or refraining from acting on any instrument reasonably believed by you
to be genuine and to have been signed or presented by the proper party or
parties. You shall not be personally liable for any act you may do or omit to do
hereunder as Escrow Agent or as attorney-in-fact for Buyer while acting in good
faith and in the exercise of your own good judgment, and any act done or omitted
by you pursuant to the advice of your own attorneys shall be conclusive evidence
of such good faith.

     9.   You are hereby expressly authorized to disregard any and all warnings
given by any of the parties or by any other person or corporation, excepting
only orders or process of courts of law, and are hereby expressly authorized to
comply with and obey orders, judgments or decrees of any court. In case you obey
or comply with any such order, judgment or decree of any court, you shall not be
liable to any of the parties or to any other person, firm or corporation by
reason of such compliance, notwithstanding any such order, judgment or decree
being subsequently reversed, modified, without jurisdiction.
<PAGE>

     10.  You shall not be liable in any respect on account of the identity,
authorities or rights of the parties executing or delivering or purporting to
execute or deliver the Agreement or any documents or papers deposited or called
for hereunder.

     11.  You shall not be liable for the limiting of any rights under the
Statute of Limitations with respect to these Joint Escrow Instructions or any
documents deposited with you.

     12.  Your responsibilities as Escrow Agent hereunder shall terminate if you
shall cease to be Clerk of the Corporation or if you shall resign by written
notice to each party. In the event of any such termination, the Corporation
shall appoint your successor as Clerk of the Corporation as successor Escrow
Agent.

     13.  If you reasonably require other or further instruments in connection
with these Joint Escrow Instructions, the necessary parties shall join in
furnishing such instruments.

     14.  It is understood and agreed that should any dispute arise with respect
to the delivery and/or ownership or right of possession of the securities held
by you hereunder, you are authorized and directed to retain in your possession
without liability to anyone all or any part of said securities until such
dispute shall have been settled either by mutual written agreement of the
parties concerned or by a final order, decree or judgment of a court of
competent jurisdiction after the time for appeal has expired and no appeal has
been perfected, but you shall be under no duty whatsoever to institute or defend
any such proceedings.

     15.  Any notice required or permitted hereunder shall be given in writing
and shall be deemed effectively given upon personal delivery or upon deposit in
the United States Post Office, by registered or certified mail with postage and
fees prepaid, addressed to each of the other parties thereunto entitled at the
following addresses, or at such other addresses as a party may designate by ten
days' advance written notice to each of the other parties.

     CORPORATION:        Millitech Corporation
                         South Deerfield Research Park
                         P. O. Box 209
                         South Deerfield, MA 01373
                         Attention: John L. Youngblood, President

     BUYER:              Mervyn FitzGerald
                         6934 Rocky Top Circle
                         Dallas, TX 75252

     ESCROW AGENT:       Clerk
                         David L. Renauld
                         Mirick, O'Connell, DeMallie & Lougee, llp
                         100 Front Street
                         Worcester, MA 01608-1477
<PAGE>

     16.  By signing these Joint Escrow Instructions, you become a party only
for the purpose of said Joint Escrow Instructions; you do not become a party to
the Agreement.

     17.  You shall be entitled to employ such legal counsel and other experts
as you may deem necessary properly to advise you in connection with your
obligations hereunder, you may rely upon the advice of such counsel, and you may
pay such counsel reasonable compensation therefor.

     18.  This instrument shall be binding upon and inure to the benefit of the
parties, and their respective successors and permitted assigns.

                                   Very truly yours,

                                   MILLITECH CORPORATION


                                   /s/ John L. Youngblood
                                   -----------------------------
                                   By:  John L. Youngblood
                                   Title:  President


                                   BUYER


                                   /s/ Mervyn FitzGerald
                                   -----------------------------
                                   Mervyn FitzGerald


                                   ESCROW AGENT


                                   /s/ David L. Renauld
                                   -----------------------------
                                   David L. Renauld, Clerk
                                   Millitech Corporation