FIRST AMENDMENT TO RIGHTS AGREEMENT

Exhibit 4.1

FIRST AMENDMENT TO RIGHTS AGREEMENT

FIRST AMENDMENT, dated as of March 23, 2009 (“First Amendment”), to Rights Agreement dated as of March 24, 2008 (the “Rights Agreement”), between Micrel, Incorporated, a California corporation (the “Company”), and Mellon Investor Services LLC, as Rights Agent (the “Rights Agent”). Capitalized terms used but not otherwise defined herein shall have the meanings ascribed to them in the Rights Agreement (defined below).

WHEREAS, the Company and the Rights Agent previously entered into the Rights Agreement; and

WHEREAS, pursuant to Section 26 of the Rights Agreement, the Company and the Rights Agent may from time to time supplement or amend any provision of the Rights Agreement in accordance with the terms of such Section 26.

NOW, THEREFORE, in consideration of the foregoing premises and mutual agreements set forth in this Amendment, the parties hereby amend the Rights Agreement as follows:

1. Section 7.1 of the Rights Agreement is hereby amended and restated in its entirety as follows:

“7.1. Exercise of Rights. Subject to Section 11.1.2 and except as otherwise provided herein, the registered holder of any Right Certificate may exercise the Rights evidenced thereby in whole or in part at any time after the Distribution Date upon surrender of the Right Certificate, with the form of election to purchase and certification on the reverse side thereof duly and properly executed, to the Rights Agent at the office of the Rights Agent designated for such purpose, together with payment of the aggregate Purchase Price for the total number of one one-thousandths of a Preferred Share (or other securities, cash or other assets) as to which the Rights are exercised, at or prior to the time (the “Expiration Date”) that is the earliest of (i) the close of business Pacific Daylight Time on March 24, 2010 (the “Final Expiration Date”), (ii) the time at which the Rights are redeemed as provided in Section 23 (the “Redemption Date”), (iii) the closing of any merger or other acquisition transaction involving the Company pursuant to an agreement of the type described in Section 13.3 at which time the Rights are deemed terminated, or (iv) the time at which the Rights are exchanged as provided in Section 27.”

2. Exhibit B to the Agreement is hereby replaced in its entirety by the Exhibit B attached hereto.

3. This First Amendment shall be effective as of the date hereof and, except as expressly set forth herein, the Rights Agreement shall remain in full force and effect and be otherwise unaffected hereby. All references to “this Agreement” in the Rights Agreement shall mean the Rights Agreement, as modified hereby.

4. This First Amendment may be executed in any number of counterparts, each of which, when executed, shall be deemed to be an original and all such counterparts shall together constitute one and the same document.

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

Signature Page to Micrel, Incorporated First Amendment to Rights Agreement

EXHIBIT B

[Form of Right Certificate]

NOT EXERCISABLE AFTER March 24, 2010 OR EARLIER IF NOTICE OF REDEMPTION OR EXCHANGE IS GIVEN OR IF THE COMPANY IS MERGED OR ACQUIRED PURSUANT TO AN AGREEMENT OF THE TYPE DESCRIBED IN SECTION 1.3(ii)(A)(z) OF THE AGREEMENT. THE RIGHTS ARE SUBJECT TO REDEMPTION AT $.01 PER RIGHT, AND TO EXCHANGE ON THE TERMS SET FORTH IN THE AGREEMENT. UNDER CERTAIN CIRCUMSTANCES (SPECIFIED IN SECTION 11.1.2 OF THE AGREEMENT), RIGHTS BENEFICIALLY OWNED BY OR TRANSFERRED TO AN ACQUIRING PERSON (AS DEFINED IN THE AGREEMENT), OR ANY SUBSEQUENT HOLDER OF SUCH RIGHTS WILL BECOME NULL AND VOID AND WILL NO LONGER BE TRANSFERABLE.

Right Certificate

MICREL, INCORPORATED

This certifies that                     , or registered assigns, is the registered owner of the number of Rights set forth above, each of which entitles the owner thereof, subject to the terms, provisions and conditions of the Rights Agreement, dated as of March 24, 2008 as the same may be amended from time to time (the “Agreement”), between Micrel, Incorporated, a California corporation (the “Company”), and Mellon Investor Services LLC, as Rights Agent (the “Rights Agent”), to purchase from the Company at any time after the Distribution Date and prior to 5:00 P.M. (California time) on March 24, 2010, at the offices of the Rights Agent, or its successors as Rights Agent, designated for such purpose, one one-thousandth of a fully paid, nonassessable share of Series A Participating Preferred Stock, no par value (the “Preferred Shares”) of the Company, at a purchase price of $36.00 per one one-thousandth of a Preferred Share, subject to adjustment (the “Purchase Price”), upon presentation and surrender of this Right Certificate with the Form of Election to Purchase and certification duly executed. The number of Rights evidenced by this Right Certificate (and the number of one one-thousandths of a Preferred Share which may be purchased upon exercise thereof) set forth above, and the Purchase Price set forth above, are the number and Purchase Price as of             ,     , 20     based on the Preferred Shares as constituted at such date. Capitalized terms used in this Right Certificate without definition shall have the meanings ascribed to them in the Agreement. As provided in the Agreement, the Purchase Price and the number of Preferred Shares which may be purchased upon the exercise of the Rights evidenced by this Right Certificate are subject to modification and adjustment upon the happening of certain events.

This Right Certificate is subject to all of the terms, provisions and conditions of the Agreement, which terms, provisions and conditions are hereby incorporated herein by reference and made a part hereof and to which Agreement reference is hereby made for a full description of the rights, limitations of rights, obligations, duties and immunities hereunder of the Rights Agent, the Company and the holders of the Right Certificates. Copies of the Agreement are on file at the principal offices of the Company and the Rights Agent.

This Right Certificate, with or without other Right Certificates, upon surrender at the offices of the Rights Agent designated for such purpose, may be exchanged for another Right Certificate or Right Certificates of like tenor and date evidencing Rights entitling the holder to purchase a like aggregate number of one one-thousandths of a Preferred Share as the Rights evidenced by the Right Certificate or Right Certificates surrendered shall have entitled such holder to purchase. If this Right Certificate shall be exercised in part, the holder shall be entitled to receive upon surrender hereof another Right Certificate or Right Certificates for the number of whole Rights not exercised.

Subject to the provisions of the Agreement, the Board of Directors may, at its option, (i) redeem the Rights evidenced by this Right Certificate at a redemption price of $.01 per Right or (ii) exchange Common Shares for the Rights evidenced by this Certificate, in whole or in part.

No fractional Preferred Shares will be issued upon the exercise of any Right or Rights evidenced hereby (other than fractions of Preferred Shares which are integral multiples of one one-thousandth of a Preferred Share, which may, at the election of the Company, be evidenced by depository receipts), but in lieu thereof a cash payment will be made, as provided in the Agreement.

No holder of this Right Certificate, as such, shall be entitled to vote or receive dividends or be deemed for any purpose the holder of the Preferred Shares or of any other securities of the Company which may at any time be issuable on the exercise hereof, nor shall anything contained in the Agreement or herein be construed to confer upon the holder hereof, as such, any of the rights of a shareholder of the Company or any right to vote for the election of directors or upon any matter submitted to shareholders at any meeting thereof, or to give or withhold consent to any corporate action, or to receive notice of meetings or other actions affecting shareholders (except as provided in the Agreement), or to receive dividends or subscription rights, or otherwise, until the Right or Rights evidenced by this Right Certificate shall have been exercised as provided in the Agreement.

If any term, provision, covenant or restriction of the Agreement is held by a court of competent jurisdiction or other authority to be invalid, void or unenforceable, the remainder of the terms, provisions, covenants and restrictions of the Agreement shall remain in full force and effect and shall in no way be affected, impaired or invalidated.

This Right Certificate shall not be valid or binding for any purpose until it shall have been countersigned by the Rights Agent.

B-2

WITNESS the facsimile signature of the proper officers of the Company and its corporate seal. Dated as of              .

B-3

[Form of Reverse Side of Right Certificate]

FORM OF ASSIGNMENT

(To be executed by the registered holder if such holder

desires to transfer the Right Certificate.)

FOR VALUE RECEIVED _____________________________________________________________________________________

hereby sells, assigns and transfers unto ___________________________________________________________________________

__________________________________________________________________________________________________________

__________________________________________________________________________________________________________

(Please print name and address of transferee)

Rights evidenced by this Right Certificate, together with all right, title and interest therein, and does hereby irrevocably constitute and appoint              Attorney, to transfer the within Right Certificate on the books of the within-named Company, with full power of substitution.

Signatures must be guaranteed by an “eligible guarantor institution” as defined in Rule 17Ad-15 promulgated under the Securities Exchange Act of 1934, as amended.

The undersigned hereby certifies that:

(1) the Rights evidenced by this Right Certificate are not Beneficially Owned by and are not being assigned to an Acquiring Person or an Affiliate or an Associate thereof; and

(2) after due inquiry and to the best knowledge of the undersigned, the undersigned did not acquire the Rights evidenced by this Right Certificate from any person who is, was or subsequently became an Acquiring Person or an Affiliate or Associate thereof.

B-4

FORM OF ELECTION TO PURCHASE

(To be executed if holder desires to exercise the Right Certificate.)

To: Micrel, Incorporated

The undersigned hereby irrevocably elects to exercise                  Rights represented by this Right Certificate to purchase the Preferred Shares issuable upon the exercise of such Rights (or such other securities or property of the Company or of any other Person which may be issuable upon the exercise of the Rights) and requests that certificates for such shares be issued in the name of:

_________________________________________________________________________________________

(Please print name and address)

_________________________________________________________________________________________

If such number of Rights shall not be all the Rights evidenced by this Right Certificate, a new Right Certificate for the balance remaining of such Rights shall be registered in the name of and delivered to:

Please insert social security

or other identifying number

_________________________________________________________________________________________

(Please print name and address)

_________________________________________________________________________________________

Signatures must be guaranteed by an “eligible guarantor institution” as defined in Rule 17Ad-15 promulgated under the Securities Exchange Act of 1934, as amended.

B-5

The undersigned hereby certifies that:

(1) the Rights evidenced by this Right Certificate are not Beneficially Owned by and are not being assigned to an Acquiring Person or an Affiliate or an Associate thereof; and

(2) after due inquiry and to the best knowledge of the undersigned, the undersigned did not acquire the Rights evidenced by this Right Certificate from any person who is, was or subsequently became an Acquiring Person or an Affiliate or Associate thereof.

NOTICE

The signature in the foregoing Form of Assignment and Form of Election to Purchase must conform to the name as written upon the face of this Right Certificate in every particular, without alteration or enlargement or any change whatsoever.

In the event the certification set forth above in the Form of Assignment or Form of Election to Purchase is not completed, the Company will deem the beneficial owner of the Rights evidenced by this Right Certificate to be an Acquiring Person or an Affiliate or Associate hereof and such Assignment or Election to Purchase will not be honored.

B-6