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Exhibit 10.28

FIRST AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT
AND RATIFICATION OF LOAN DOCUMENTS

        THIS FIRST AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT AND
RATIFICATION OF LOAN DOCUMENTS dated as of August 31, 2007 (this "First
Amendment") is entered into by and between CITIZENS BANK OF MASSACHUSETTS
(together with its successors and assigns the "Bank"), a Massachusetts bank with
a principal place of business at 28 State Street, Boston, Massachusetts 02109,
and HITTITE MICROWAVE CORPORATION (the "Borrower"), a Delaware corporation with
a principal place of business at 20 Alpha Road, Chelmsford, Massachusetts 01824.

        WHEREAS, the Bank and the Borrower entered into an Equipment and
Commercial Revolving Line of Credit Agreement dated as of September 30, 2001 (as
amended by various amendments, including the First Amendment to Equipment and
Commercial Revolving Credit Agreement and Ratification of Loan Documents dated
as of June 25, 2003 and the Second Amendment to Equipment and Commercial
Revolving Credit Agreement and Ratification of Loan Documents dated as of
July 7, 2004, collectively the "Original Credit Agreement") pursuant to which
the Bank extended to the Borrower (i) a revolving line of credit facility in the
original principal amount of Four Million Dollars ($4,000,000.00) (the
"Revolving Credit") and (ii) an equipment line of credit in the original
principal amount of Four Million Dollars ($4,000,000.00) (the "Equipment
Credit"); and

        WHEREAS, the Bank and the Borrower entered into an Amended and Restated
Credit Agreement dated as of July 31, 2006 (as the same may be amended,
modified, extended or replaced from time to time, including by this First
Amendment, the "Amended and Restated Credit Agreement"), pursuant to which,
among other things, the parties agreed to (i) eliminate the Equipment Credit,
(ii) increase the amount available under the Revolving Credit to Thirty Million
Dollars ($30,000,000.00) evidenced by a revolving credit note in the original
principal amount of $30,000,000.00 dated July 31, 2006 (the "Original Revolving
Note"), and (iii) amend and restate the Original Credit Agreement; and

        WHEREAS, subject to the terms of this First Amendment, the Borrower and
the Bank have agreed to extend the Maturity Date of the Revolving Credit from
July 31, 2007 to August 30, 2008;

        NOW, THEREFORE, for good and valuable consideration, the receipt of
which are hereby acknowledged, the parties hereby agree as follows:

        1.     The Amended and Restated Credit Agreement is hereby amended as
follows:

(a)The definition of "Maturity Date" at the bottom of page 2 is hereby amended
by deleting the date "July 31, 2007" and substituting the date "August 30, 2008"
in lieu thereof, thereby extending the Maturity Date of the Revolving Credit to
August 30, 2008.

        2.     Simultaneously herewith and as a condition of the effectiveness
of this First Amendment, the Borrower shall execute and deliver, in addition to
this First Amendment, the following to the Bank:

(a)An Allonge to and Amendment of Revolving Credit Note;

(b)A Secretary Certificate attesting to the incumbency and authority of the
persons executing this First Amendment and all other related documents; and

(c)Such other documents and certificates as the Bank or its counsel may
reasonably require, with all documents to be in form and substance satisfactory
to the Bank and its counsel.

        3.     The Borrower hereby represents and warrants that, to the best of
its knowledge: (a) the representations and warranties contained in Section 4 of
the Amended and Restated Credit Agreement remain true and accurate in all
material respects; (b) there has not occurred any material adverse change in the
business, assets, financial condition or prospects of the business of the
Borrower since

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the date of the last financial statements submitted to the Bank by the Borrower;
and (c) the Borrower has no offsets, set-offs or other claims of any kind
against the Bank as of the date hereof, and, to the extent the Borrower has any
such offsets, set-offs, claims, the Borrower hereby waives the same.

        4.     The Borrower agrees to execute, acknowledge and deliver such
further instruments as the Bank shall reasonably require in order to effectuate
the intent of this First Amendment.

        5.     The Borrower will pay or reimburse the Bank, on demand, for all
reasonable expenses (including, without limitation, reasonable counsel fees and
expenses) incurred or paid by the Bank in connection with the making of the
Loans, including this First Amendment, and the enforcement by the Bank of its
rights as against the Borrower or any other person primarily or secondarily
liable to the Bank hereunder or thereunder; the administration, supervision,
protection or realization on any collateral held by the Bank as security for any
obligation of the Borrower or any other person primarily or secondarily liable
with respect thereto. In addition, the Borrower shall pay any and all stamp and
other taxes and fees payable or determined to by payable in connection with the
execution, delivery, filing and recording of any of the Loan Documents and the
other documents to be delivered under any such Loan Documents, and agree to save
the Bank harmless from and against any and all liabilities with respect to or
resulting from any delay in paying or omission to pay such taxes and fees.

        6.     This First Amendment may be executed in any number of
counterparts, and when each party has signed and delivered at least one such
counterpart, each counterpart shall be considered an original, and when taken
together with other signed counterparts, shall constitute one agreement, which
shall be binding upon and effective as to all parties. Time of all payments and
provisions hereof is of strict essence. The provisions of this First Amendment
are hereby declared to be severable, and the invalidity of any provision or
application thereof shall not affect any other provision or any other
application thereof. This First Amendment is binding upon and shall inure to the
benefit of the parties hereto, their heirs, executors, administrators,
successors and assigns. This First Amendment shall be deemed to have been
executed and delivered within The Commonwealth of Massachusetts, and the rights
and obligations of the parties hereto shall be construed and enforced in
accordance with, and governed by, the laws of The Commonwealth of Massachusetts.
Each party has cooperated in the drafting and preparation of this Agreement;
hence, in any construction to be made of this First Amendment, the same shall
not be construed against any party. Facsimile and scanned signatures shall be
deemed originals for all purposes.

        7.     All capitalized terms not otherwise defined herein shall have the
meanings ascribed to them in the Amended and Restated Credit Agreement, as
amended hereby. All references to the loan documents or "Loan Documents" shall
hereinafter be deemed to include this First Amendment.

        8.     Except as set forth herein, the Borrower hereby acknowledges and
agrees that this First Amendment and the Amended and Restated Credit Agreement,
and all loan documents now or heretofore executed and delivered by the Borrower
to the Bank, securing the Obligations, as defined in the Amended and Restated
Credit Agreement, remain in full force and effect and hereby ratify and confirm
that all Obligations of the Borrower to the Bank, whether now existing or
hereafter arising, remain in full force and effect.

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        IN WITNESS WHEREOF, the parties have executed, or caused this First
Amendment to be executed, by their respective officers thereunto duly
authorized, as of the day first written above and it and shall take effect as a
sealed instrument.

    HITITTE MICROWAVE CORPORATION
/s/  NORMAN G. HILDRETH, JR.      

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By:
/s/  WILLIAM W. BOECKE      

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Witness   Name: WILLIAM W. BOECKE     Title: V.P. CHIEF FINANCIAL OFFICER
 
 
CITIZENS BANK OF MASSACHUSETTS

 
 
By:
/s/  CHRISTOPHER J. WICKLES      

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    Christopher J. Wickles, Vice President

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ALLONGE TO AND AMENDMENT OF REVOLVING CREDIT NOTE

        Reference is hereby made to a certain Revolving Credit Note dated
July 31, 2006 in the original principal amount of Thirty Million Dollars
($30,000,000.00) (the "Original Revolving Note") executed and delivered by
HITTITE MICROWAVE CORPORATION (the "Borrower"), a Delaware corporation, payable
to the order of CITIZENS BANK OF MASSACHUSETTS (the "Bank").

        WHEREAS, the Bank and the Borrower entered into an Amended and Restated
Credit Agreement dated as of July 31, 2006 (together will all modifications and
amendments the "Amended and Restated Credit Agreement") pursuant to which the
Bank extended a Revolving Credit to the Borrower in the original principal
amount of $30,000,000.00 and the Borrower executed and delivered the Original
Revolving Note; and

        WHEREAS, the Borrower has requested that the Maturity Date of the
Revolving Credit be extended from July 31, 2007 to August 30, 2008 and the Bank
has agreed, subject to the execution and/or delivery of, among other things, the
First Amendment to Amended and Restated Credit Agreement and Ratification of
Loan Documents and this Allonge;

        NOW, THEREFORE, the parties agree as follows:

        1.     The Original Revolving Note is hereby amended by deleting the
date "July 31, 2007" from the first paragraph thereof and substituting the date
"August 30, 2008" in lieu thereof, thereby extending the Maturity Date to
August 30, 2008.

        2.     In all other respects, the Original Revolving Note is ratified
and confirmed as being in full force and effect and as being secured by the same
collateral, which secured the Original Revolving Note.

[This Page Ends Here—Signature Page to Follow]

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Signed as a sealed instrument as of August 31, 2007.

    HITTITE MICROWAVE CORPORATION
/s/  NORMAN G. HILDRETH, JR.      

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By:
/s/  WILLIAM W. BOECKE      

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Witness   Name: WILLIAM W. BOECKE     Title: V.P. CHIEF FINANCIAL OFFICER
 
 
CITIZENS BANK OF MASSACHUSETTS

 
 
By:
/s/  CHRISTOPHER J. WICKLES      

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    Christopher J. Wickles, Vice President

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FIRST AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT AND RATIFICATION OF
LOAN DOCUMENTS