<PAGE>

                                                                   EXHIBIT 10.32


                                PROMISSORY NOTE

$7,500,000.00                                                  February 29, 2000


     FOR VALUE RECEIVED, on or before December 31, 2000 ("Maturity Date") RF
                                                          -------------
MONOLITHICS, INC. ("Borrower"), does hereby unconditionally promise to pay to
                    --------
the order of BANK ONE, TEXAS, NATIONAL ASSOCIATION ("Bank"), at its offices in
                                                     ----
Dallas County, Texas at 1717 Main Street, Dallas, Texas 75201, the principal
amount of SEVEN MILLION FIVE HUNDRED THOUSAND AND NO/100 DOLLARS ($7,500,000.00)
("Total Principal Amount"), or such amount less than the Total Principal Amount
  ----------------------
which is outstanding from time to time if the total amount outstanding hereunder
is less than the Total Principal Amount, in lawful money of the United States of
America, together with interest on such portion of the Total Principal Amount
which has been drawn until paid at the rates per annum provided below.

     1.   Definitions.  For purposes of this promissory note ("Note"), unless
          -----------                                          ----
the context otherwise requires, in addition to the other terms defined herein,
the following terms shall have the definitions assigned to such terms as
follows:

     "Adjusted LIBOR Rate" shall mean with respect to each Interest Period, on
      -------------------
any day thereof an amount equal to the sum of (i) four percent (4.0%), plus,
                                                                       ----
(ii) the quotient of (a) the LIBOR Rate with respect to such Interest Period,

divided by (b) the remainder of 1.0 less the Reserve Requirement in effect on
----------                          ----
such day.  Each determination by Bank of the Adjusted LIBOR Rate shall, in the
absence of manifest error, be conclusive and binding.

     "Business Day" shall mean any day other than a Saturday, Sunday, or any
      ------------
other day on which national banking associations are authorized to be closed.

     "Consequential Loss" shall mean, with respect to Borrower's payment of all
      ------------------
or any portion of the then-outstanding principal amount of any LIBOR Balance on
a day other than the last day of the Interest Period related thereto, any loss,
cost or expense incurred by Bank in redepositing such principal amount,
including the sum of (i) the interest which, but for such payment, Bank would
have earned in respect of such principal amount so paid, for the remainder of
the Interest Period applicable to such sum, reduced, if Bank is able to
redeposit such principal amount so paid for the balance of such Interest Period,
by the interest earned by Bank as a result of so redepositing such principal
amount plus (ii) any expense or penalty incurred by Bank on redepositing such
       ----
principal amount.

     "Contract Rate" shall mean a rate of interest based upon the Adjusted LIBOR
      -------------
Rate or Prime Rate in effect at any time.

     "Dollars" shall mean lawful currency of the United States of America.
      -------

     "Event of Default" shall mean the occurrence of an "Event of Default" as
      ----------------
defined in the Loan Agreement.

PROMISSORY NOTE - Page 1
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     "Excess Interest Amount" shall mean, on any date, the amount by which (i)
      ----------------------
the amount of all interest which would have accrued prior to such date on the
principal of this Note, had the applicable Contract Rate at all times been in
effect without limitation by the Maximum Rate, exceeds (ii) the aggregate amount
                                               -------
of interest accrued on this Note on or prior to such date.

     "Interest Notice" shall mean the notice given by Borrower to Bank of the
      ---------------
Interest Options selected hereunder.  Each Interest Notice shall specify the
Interest Option selected, the amount of the unpaid principal balance of this
Note to bear interest at the rate selected and, if the Adjusted LIBOR Rate is
specified, the length of the applicable Interest Period.  An Interest Notice may
be written or oral (if promptly confirmed thereafter in writing) and Bank is
hereby authorized and directed to honor all telephonic Interest Notices from any
person authorized to request advances hereunder.

     "Interest Option" shall have the meaning assigned to such term in paragraph
      ---------------                                                  ---------
6 hereof.
-

     "Interest Payment Date" shall mean (i) in the case of the Prime Rate
      ---------------------
Balance, on the first day of each month during the term of this Note beginning
on March 1, 2000, and on the Maturity Date, and (ii) in the case of any LIBOR
Balance, the last day of the corresponding Interest Period with respect to such
LIBOR Balance and on the Maturity Date.

     "Interest Period" shall mean, with respect to any LIBOR Balance, a period
      ---------------
commencing: (i) on any date which, pursuant to an Interest Notice, the principal
amount of such LIBOR Balance begins to accrue interest at the Adjusted LIBOR
Rate, or (ii) the Business Day following the last day of the immediately
preceding Interest Period in the case of a rollover to a successive Interest
Period, and ending one (1) month, two (2) months, or three (3) months thereafter
as Borrower shall elect in accordance with the provisions hereof, provided that
(A) any Interest Period which would otherwise end on a day which is not a London
Business Day shall be extended to the next succeeding London Business Day and
(B) any Interest Period which would otherwise end after the Maturity Date shall
end on the Maturity Date.

     "LIBOR Balance" shall mean any principal balance of this Note which,
      -------------
pursuant to an Interest Notice, bears interest at a rate based upon the Adjusted
LIBOR Rate for the Interest Period specified in such Interest Notice.

     "LIBOR Rate" shall mean, with respect to each Interest Period, the offered
      ----------
rate for U.S. Dollar deposits of not less than $1,000,000.00 for a period of
time equal to the Interest Period as of 11:00 a.m. City of London, England time
two (2) London Business Days prior to the first date of each Interest Period as
shown on the display designated as "British Bankers Association Interest
Settlement Rates" on the Telerate System ("Telerate"), Page 3750 or Page 3740,
or such other page or pages as may replace such pages on Telerate for the
purpose of displaying such rate; provided, however, that if such rate is not
available on the Telerate then such offered rate shall be otherwise
independently determined by Bank from an alternate, substantially similar
independent source available to Lender or shall be calculated by Bank by a
substantially similar methodology as that theretofore used to determine such
offered rate in Telerate.  The LIBOR Rate for the Interest Period to which it
relates shall be rounded upward, if necessary, to the nearest one-one hundredth
of one percent.

PROMISSORY NOTE - Page 2
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     "Loan Agreement" shall mean that certain Letter Loan Agreement dated March
      --------------
8, 1996  by and between Bank and Borrower as amended by that certain First
Amendment to Loan Agreement dated as of December 31, 1997 by and between
Borrower and Bank, by that certain Second Amendment to Loan Agreement dated as
of July 15, 1999 by and between Borrower and Bank, and as such agreement may be
further amended, restated, or otherwise modified from time to time.

     "Loan Documents" shall mean this Note, the Loan Agreement, and all other
      --------------
documents evidencing, securing, governing, guaranteeing, and/or pertaining to
this Note.

     "London Business Day" shall mean any day other than a Saturday, Sunday, or
      -------------------
a day on which banking institutions are generally authorized or obligated by law
or executive order to close in the City of London, England.

     "Maximum Rate" shall mean, with respect to the holder hereof, the maximum
      ------------
nonusurious interest rate, if any, that at any time, or from time to time, may
be contracted for, taken, reserved, charged, or received on the indebtedness
evidenced by this Note under the laws which are presently in effect in the
United States and the State of Texas applicable to such holder and such
indebtedness or, to the extent permitted by law, under such applicable laws of
the United States and the State of Texas which may hereafter be in effect and
which allow a higher maximum nonusurious interest rate than applicable laws now
allow.  To the extent that Chapter 303 of the Texas Credit Code, as supplemented
by the Texas Credit Title, is relevant to any holder of this Note for the
purposes of determining the Maximum Rate, each such holder elects to determine
such applicable legal rate under the Act pursuant to the "weekly rate ceiling,"
from time to time in effect, as referred to in said Chapter 303; subject,
however, to the limitations on such applicable ceiling referred to and defined
in said Chapter 303, and further subject to any right such holder may have
subsequently, under applicable law, to change the method of determining the
Maximum Rate.  If no Maximum Rate is established by applicable law, then the
Maximum Rate shall be equal to eighteen percent (18.0%).

     "Prime Rate" shall mean the rate established from time to time by Bank as
      ----------
its Prime Rate of interest (which may not be the lowest, best or most favorable
rate of interest which Bank may charge on loans to its customers).

     "Prime Rate Balance" shall mean that portion of the principal balance of
      ------------------
this Note bearing interest at a rate based upon the Prime Rate.

     "Regulation D" shall mean Regulation D of the Board of Governors of the
      ------------
Federal Reserve System from time to time in effect and shall include any
successor or other regulation relating to reserve requirements applicable to
member banks of the Federal Reserve System.

     "Reserve Requirement" shall, on any day, mean that percentage (expressed as
      -------------------
a decimal fraction) which is in effect on such day, as provided by the Board of
Governors of the Federal Reserve System (or any successor governmental body) for
determining the reserve requirements (including, without limitation, basic,
supplemental, marginal, and emergency reserves) under Regulation D with respect
to "Eurocurrency liabilities" as currently defined in Regulation D, or under any
similar or successor regulation.  For purposes of this definition, any LIBOR
Balances

PROMISSORY NOTE - Page 3
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hereunder shall be deemed "Eurocurrency liabilities" under Regulation D
without benefit of or credit for prorations, exemptions, or offsets under
Regulation D.  Bank's determination of the Reserve Requirement shall be
conclusive.

     2.   Payments of Interest and Principal.  Interest on the unpaid principal
          ----------------------------------
balance of this Note shall be due and payable on each Interest Payment Date as
it accrues and the entire unpaid principal balance of this Note, and all accrued
but unpaid interest thereon, shall be due and payable on the Maturity Date.

     3.   Rates of Interest.  The unpaid principal of the Prime Rate Balance
          -----------------
shall bear interest at a rate per annum which shall from day to day be equal to
the lesser of (i) the Prime Rate in effect from day to day, plus one percent
                                                            ----
(1.0%), or (ii) the Maximum Rate.  The unpaid principal of each LIBOR Balance
shall bear interest at a rate per annum which shall from day to day be equal to
the lesser of (i) the Adjusted LIBOR Rate for the Interest Period in effect with
respect to such LIBOR Balance, or (ii) the Maximum Rate.  Each change in the
interest rate applicable to a Prime Rate Balance shall become effective without
prior notice to Borrower automatically as of the opening of business on the date
of such change in the Prime Rate.  Interest on this Note shall be calculated on
the basis of the actual days elapsed in a year consisting of 360 days.

     4.   Interest Recapture. On each Interest Payment Date or any other date on
          ------------------
which interest payments are required hereunder, if Bank does not receive
interest on this Note computed at the Contract Rate because such Contract Rate
exceeds or has exceeded the Maximum Rate, then Borrower shall, upon the written
demand of Bank, pay to Bank in addition to the interest otherwise required to be
paid hereunder, on each Interest Payment Date thereafter, the Excess Interest
Amount (calculated as of such later Interest Payment Date); provided that in no
event shall Borrower be required to pay interest at a rate exceeding the Maximum
Rate.

     5.   Interest on Past Due Amounts.  To the extent any interest is not paid
          ----------------------------
on or before the fifth day after it becomes due and payable, Bank may, at its
option, add such accrued but unpaid interest to the principal of this Note.
Notwithstanding anything herein to the contrary, upon an Event of Default or at
maturity, whether by acceleration or otherwise, all principal of this Note
shall, at the option of Bank, bear interest at the Maximum Rate until paid.

     6.   Interest Option. Subject to the provisions hereof, Borrower shall have
          ---------------
the option (an "Interest Option") of having designated portions of the unpaid
                ---------------
principal balance of this Note bear interest at a rate based upon the Adjusted
LIBOR Rate or Prime Rate as provided in paragraph 3 hereof; provided, however,
                                        -----------
that the selection of the Adjusted LIBOR Rate for a particular Interest Period
shall not be for less than $1,000,000.00 of unpaid principal or $250,000
increments above such minimum amount.  The Interest Option shall be exercised in
the manner provided below:

          (i)   At Time of Borrowing. Contemporaneously with each request for an
                --------------------
     advance by Borrower under paragraph 9 herein, Borrower shall give Bank an
                               -----------
     Interest Notice indicating the initial Interest Option selected with
     respect to the principal balance of such advance.

PROMISSORY NOTE - Page 4
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          (ii)  At Expiration of Interest Periods.  At least two (2) Business
                ---------------------------------
     Days prior to the termination of any Interest Period, Borrower shall give
     Bank an Interest Notice indicating the Interest Option to be applicable to
     the corresponding LIBOR Balance upon the expiration of such Interest
     Period.  If the required Interest Notice shall not have been timely
     received by Bank prior to the expiration of the then-relevant Interest
     Period, Borrower shall be deemed to have selected a rate based upon the
     Prime Rate to be applicable to such LIBOR Balance upon the expiration of
     such Interest Period and to have given Bank notice of such selection.

          (iii)  Conversion From Prime Rate.  During any period in which any
                 --------------------------
     portion of the principal hereof bears interest at a rate based upon the
     Prime Rate, Borrower shall have the right, on any Business Day (the
     "Conversion Date"), to convert all or a portion of such principal amount
     ----------------
     from the Prime Rate Balance to a LIBOR Balance by giving Bank an Interest
     Notice of such selection at least two (2) Business Days prior to such
     Conversion Date.

An Interest Notice may be written or oral and Bank is hereby authorized and
directed to honor all telephonic Interest Notices hereunder.  Borrower agrees to
indemnify and hold Bank harmless from any loss or liability incurred by Bank in
connection with honoring any telephonic or other oral Interest Notices.  All
written Interest Notices are effective only upon receipt by Bank.  Each Interest
Notice shall be irrevocable and binding upon Borrower.

     7.   Special Provisions For LIBOR Pricing.
          ------------------------------------

          a.  Inadequacy of LIBOR Loan Pricing.  If Bank determines that, by
              --------------------------------
reason of circumstances affecting the interbank eurodollar market generally,
deposits in Dollars (in the applicable amounts) are not being offered to United
States financial institutions in the interbank eurodollar market for such
Interest Period, or that the rate at which such Dollar deposits are being
offered will not adequately and fairly reflect the cost to Bank of making or
maintaining a LIBOR Balance for the applicable Interest Period, Bank shall
forthwith give notice thereof to Borrower, whereupon until Bank notifies
Borrower that the circumstances giving rise to such suspension no longer exist,
(i) the right of Borrower to select an Interest Option based upon the LIBOR Rate
shall be suspended, and (ii) Borrower shall be deemed to have converted each
LIBOR Balance to the Prime Rate Balance in accordance with the provisions hereof
on the last day of the then-current Interest Period applicable to such LIBOR
Balance.

          b.  Illegality.  If the adoption of any applicable law, rule, or
              ----------
regulation, or any change therein, or any change in the interpretation or
administration thereof by any governmental authority, central bank, or
comparable agency charged with the interpretation or administration thereof, or
compliance by Bank with any request or directive (whether or not having the
force of law) of any such authority, central bank, or comparable agency shall
make it unlawful or impossible for Bank to make or maintain a LIBOR Balance,
Bank shall so notify Borrower.  Upon receipt of such notice, Borrower shall be
deemed to have converted any LIBOR Balance to the Prime Rate Balance, on either
(i) the last day of the then-current Interest Period applicable to such LIBOR
Balance if Bank may lawfully continue to maintain and fund such LIBOR Balance to
such day, or (ii) immediately, if Bank may not lawfully continue to maintain
such LIBOR Balance to such day.

PROMISSORY NOTE - Page 5
<PAGE>

     8.   Extension, Place and Application of Payments. Should the principal of,
          --------------------------------------------
or any interest on, this Note become due and payable on any day other than a
Business Day, the maturity thereof shall be extended to the next succeeding
Business Day, and interest shall be payable with respect to such extension. All
payments of principal of, and interest on, this Note shall be made in lawful
money of the United States of America in immediately available funds. Payments
made to Bank by Borrower hereunder shall be applied first to accrued but unpaid
interest and then to outstanding principal.

     9.   Advances.  Subject to the terms of this Note and the Loan Agreement,
          --------
Borrower may request advances (each an "Advance") hereunder and make payments
                                        -------
from time to time during the term of this Note, provided that it is understood
and agreed that the aggregate principal amount outstanding from time to time
hereunder shall not exceed the sum of the Total Principal Amount.  The unpaid
balance of this Note shall increase and decrease with each new Advance or
payment hereunder as the case may be.  This Note shall not be deemed terminated
or canceled prior to the Maturity Date, although the entire principal balance
hereof may from time to time be paid in full.  Subject to the provisions of this
Note and the Loan Agreement, Borrower may borrow, repay, and reborrow hereunder
from the date hereof until the Maturity Date.  Each Advance hereunder shall be
in an amount not less than $10,000.00 or an integral multiple thereof.  If any
Advance request is received by Bank on or prior to 12:00 p.m. (Dallas, Texas
time) on funds designated to accrue interest at the Prime Rate, Bank shall make
available at Bank's office in Dallas, Texas not later than 2:00 p.m. (Dallas,
Texas time) on the day of such Advance request (or the date specified in such
request), the amount of such request in immediately available funds.  If any
Advance request is received by Bank after 12:00 p.m. (Dallas, Texas time) on
funds designated to accrue interest at the Prime Rate, Bank shall make available
at Bank's office in Dallas, Texas not later than 2:00 p.m. (Dallas, Texas time)
on the Business Day after the day of such request (or a later date if specified
in such request), the amount of such request in immediately available funds.
Each request for an Advance on funds designated to accrue interest at the
Adjusted LIBOR Rate must be received by Bank not less than three (3) Business
Days prior to the date upon which the Advance requested is desired by Borrower.
Each request for an Advance hereunder must be accompanied by an Interest Notice
for the funds to be advanced thereunder; provided, however, if an Interest
Notice does not accompany an Advance request, Borrower shall be deemed to have
designated the Prime Rate.  Each request for an Advance by Borrower hereunder
shall be irrevocable and binding on Borrower.  An Advance request may be written
or oral and Bank is authorized and directed to honor all telephonic requests for
Advances from any person authorized to request Advances hereunder.

     Borrower agrees to indemnify and hold Bank harmless from any loss or
liability incurred by Bank in connection with honoring any such telephonic or
other oral requests for Advances.

     All written Advance requests are effective only upon receipt by Bank.

     10.  Loan Agreement.  This Note is subject to the terms and provisions of
          --------------
the Loan Agreement, which is incorporated herein by reference for all purposes.
The holder of this Note is entitled to the benefits provided in the Loan
Agreement.

     11.  Prepayments; Consequential Loss.  Any prepayment made hereunder shall
          -------------------------------
be made together with all interest accrued but unpaid on this Note through the
date of such prepayment.

PROMISSORY NOTE - Page 6
<PAGE>

Contemporaneously with each prepayment of principal, Borrower shall give Bank
written or oral notice indicating whether such prepayment is to be applied to
the Prime Rate Balance or a particular LIBOR Balance. If such notice is not
timely received by Bank, Borrower shall be deemed to have selected to prepay the
Prime Rate Balance and, if any sums remain after satisfying all of the Prime
Rate Balance, the remaining sums shall be applied to any LIBOR Balance(s) as
Bank determines in its sole discretion. Borrower agrees to indemnify and hold
Bank harmless from any loss or liability incurred by Bank in connection with
honoring telephonic or other oral notices indicating how a prepayment is to be
applied. If Borrower makes any payment of principal with respect to any LIBOR
Balance on any day prior to the last day of the Interest Period applicable to
such LIBOR Balance, Borrower shall reimburse Bank on demand the Consequential
Loss incurred by Bank as a result of the timing of such payment. A certificate
of Bank setting forth the basis for the determination of a Consequential Loss
shall be delivered to Borrower and shall, in the absence of manifest error, be
conclusive and binding as to such determination and amount.

     12.  Additional Costs.  Borrower agrees to pay to Bank all Additional Costs
          ----------------
within ten (10) days of receipt by Borrower from Bank of a statement setting
forth the amount or amounts due and the basis for the determination from time to
time of such amount or amounts, which statement shall be conclusive and binding
upon Borrower absent manifest error.  Failure on the part of Bank to demand
compensation for any Additional Costs in any Interest Period shall not
constitute a waiver of Bank's right to demand compensation for any Additional
Costs incurred during any such Interest Period or in any other subsequent or
prior Interest Period.  The term "Additional Costs" shall mean such additional
                                  ----------------
amount or amounts as Bank shall reasonably determine will compensate Bank for
actual costs incurred by Bank in maintaining LIBOR Rates on the LIBOR Balances
or any portion thereof as a result of any change, after the date of this Note,
in applicable law, rule or regulation or in the interpretation or administration
thereof by, or the compliance by Bank with any request or directive from, any
domestic or foreign governmental authority charged with the interpretation or
administration thereof (whether or not having the force of law) or by any
domestic or foreign court changing the basis of taxation of payments to Bank of
the LIBOR Balances or interest on the LIBOR Balances or any portion thereof at
an Adjusted LIBOR Rate or any other fees or amounts payable under this Note or
the Loan Agreement (other than taxes imposed on all or any portion of the
overall net income of Bank by the State of Texas or the Federal government), or
imposing, modifying or applying any reserve, special deposit or similar
requirement against assets of, deposits with or for the account of, credit
extended by, or any other acquisition of funds for loans by Bank, or imposing on
Bank, as the case may be, or on the London interbank market any other condition
affecting this Note, the Loan Agreement or the LIBOR Balances so as to increase
the cost of Bank making or maintaining Adjustable LIBOR Rates with respect to
the LIBOR Balances or any portion thereof or to reduce the amount of any sum
received or receivable by Bank under this Note or the Loan Agreement (whether of
principal, interest or otherwise), by an amount deemed by Bank in good faith to
be material, but without duplication for any Reserve Requirement.

     13.  Notices.  Except as otherwise specified herein, all notices and
          -------
requests required or permitted hereunder shall be given in accordance with
paragraph 16 of the Loan Agreement.
------------

     14.  Legal Fees.  If this Note is placed in the hands of any attorney for
          ----------
collection, or if it is collected through any legal proceeding at law or in
equity or in bankruptcy, receivership, or other

PROMISSORY NOTE - Page 7
<PAGE>

court proceedings, Borrower agrees to pay all costs of collection including, but
not limited to, court costs and reasonable attorneys' fees.

     15.  Waivers.  Borrower and each surety, endorser, guarantor, and any other
          -------
party ever liable for payment of any sums of money payable on this Note, jointly
and severally waive presentment and demand for payment, protest, notice of
protest, intention to accelerate, acceleration and non-payment, or other notice
of default, and agree that their liability under this Note shall not be affected
by any renewal or extension in the time of payment hereof, or in any
indulgences, or by any release or change in any security for the payment of this
Note, and hereby consent to any and all renewals, extensions, indulgences,
releases, or changes, regardless of the number of such renewals, extensions,
indulgences, releases, or changes; provided, however, this Note may not be
amended or modified except by a written instrument signed by the Borrower and
the holder hereof.  No waiver by Bank of any of its rights or remedies hereunder
or under any other document evidencing or securing this Note or otherwise shall
be considered a waiver of any other subsequent right or remedy of Bank; no delay
or omission in the exercise or enforcement by Bank of any rights or remedies
shall ever be construed as a waiver of any right or remedy of Bank; and no
exercise or enforcement of any such rights or remedies shall ever be held to
exhaust any right or remedy of Bank.

     16.  Remedies.  Upon the occurrence of any Event of Default, the holder
          --------
hereof may, at its option, (i) declare the entire unpaid balance of principal
and accrued but unpaid interest on this Note to be immediately due and payable,
(ii) refuse to advance any additional amounts under this Note, (iii) foreclose
all liens securing payment hereof, (iv) pursue any and all other rights,
remedies, and recourses available to the holder hereof, including but not
limited to, any such rights, remedies, or recourses under the Loan Documents, at
law or in equity, or (v) pursue any combination of the foregoing.

     17.  Spreading.  Any provision herein, or in any document securing this
          ---------
Note, or any other document executed or delivered in connection herewith, or in
any other agreement or commitment, whether written or oral, expressed or
implied, to the contrary notwithstanding, neither Bank nor any holder hereof
shall in any event be entitled to receive or collect, nor shall or may amounts
received hereunder be credited, so that Bank or any holder hereof shall be paid,
as interest, a sum greater than the maximum amount permitted by applicable law
to be charged to the person, partnership, firm or corporation primarily
obligated to pay this Note at the time in question.  If any construction of this
Note or any document securing this Note, or any and all other papers, agreements
or commitments, indicate a different right given to Bank or any holder hereof to
ask for, demand or receive any larger sum as interest, such is a mistake in
calculation or wording which this clause shall override and control, it being
the intention of the parties that this Note, and all other instruments securing
the payment of this Note or executed or delivered in connection herewith shall
in all things comply with the applicable law and proper adjustments shall
automatically be made accordingly.  In the event that Bank or any holder hereof
ever receives, collects or applies as interest any sum in excess of the Maximum
Rate, if any, such excess amount shall be applied to the reduction of the unpaid
principal balance of this Note, and if this Note is paid in full, any remaining
excess shall be paid to Borrower.  In determining whether or not the interest
paid or payable, under any specific contingency, exceeds the Maximum Rate, if
any, Borrower and Bank or any holder hereof shall, to the maximum extent
permitted under applicable law: (a) characterize any nonprincipal payment as an
expense or fee

PROMISSORY NOTE - Page 8
<PAGE>

rather than as interest, (b) exclude voluntary prepayments and the effects
thereof, (c) "spread" the total amount of interest throughout the entire term of
this Note; provided that if this Note is paid and performed in full prior to the
end of the full contemplated term hereof, and if the interest received for the
actual period of existence thereof exceeds the Maximum Rate, if any, Bank or any
holder hereof shall refund to Borrower the amount of such excess, or credit the
amount of such excess against the aggregate unpaid principal balance of all
advances made by the Bank or any holder hereof under this Note at the time in
question.

     18.  Choice of Law.  This Note is being executed and delivered, and is
          -------------
intended to be performed in the State of Texas.  Except to the extent that the
laws of the United States may apply to the terms hereof, the substantive laws of
the State of Texas shall govern the validity, construction, enforcement and
interpretation of this Note.  In the event of a dispute involving this Note or
any other instruments executed in connection herewith, the undersigned
irrevocably agrees that venue for such dispute shall lie in any court of
competent jurisdiction in Dallas County, Texas.

     19.  Renewal.  This Note renews and extends amounts unpaid this date under
          -------
that certain promissory note dated July 15, 1999 in the stated principal amount
of $7,500,000.00 executed by Borrower and payable to the order of Bank.

     20.  Entire Agreement.  THIS NOTE (TOGETHER WITH THE OTHER LOAN DOCUMENTS)
          ----------------
CONTAINS THE ENTIRE AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY
EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE
PARTIES.  THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.



                              RF MONOLITHICS, INC.


                              By:       /s/ David Kirk
                                 ---------------------------
                              Name:     David Kirk
                                   -------------------------
                              Title:    President & CEO
                                    ------------------------

PROMISSORY NOTE - Page 9