<PAGE>

                                                                     Exhibit 4.1

                             AMENDED AND RESTATED
                         CERTIFICATE OF INCORPORATION
                                      OF
                      TERAYON COMMUNICATION SYSTEMS, INC.


                                      I.

     The name of this corporation is Terayon Communication Systems, Inc.

                                      II.

     The address of the registered office of the corporation in the State of
Delaware is 1013 Centre Road, City of Wilmington, 19805, County of New Castle
and the name of the registered agent of the corporation in the State of Delaware
at such address is Corporation Service Company.

                                     III.

     The purpose of this corporation is to engage in any lawful act or activity
for which a corporation may be organized under the General Corporation Law of
the State of Delaware.

                                      IV.

          This corporation is authorized to issue two classes of stock to be
designated, respectively, "Common Stock" and "Preferred Stock." The total number
of shares which the corporation is authorized to issue is Fifty Million
(50,000,000) shares. Forty-Five Million (45,000,000) shares shall be Common
Stock, each having a par value of one tenth of one cent ($.001). Five Million
(5,000,000) shares shall be Preferred Stock, each having a par value of one
tenth of one cent ($.001).

     The Preferred Stock may be issued from time to time in one or more series.
The Board of Directors is hereby authorized, by filing a certificate (a
"Preferred Stock Designation") pursuant to the Delaware General Corporation Law,
to fix or alter from time to time the designation, powers, preferences and
rights of the shares of each such series and the qualifications, limitations or
restrictions of any wholly unissued series of Preferred Stock, and to establish
from time to time the number of shares constituting any such series or any of
them; and to increase or decrease the number of shares of any series subsequent
to the issuance of shares of that series, but not below the number of shares of
such series then outstanding.  In case the number of shares of any series shall
be decreased in accordance with the foregoing sentence, the shares constituting
such decrease shall resume the status that they had prior to the adoption of the
resolution originally fixing the number of shares of such series.

                                       1
<PAGE>

                                      V.

     A.   For the management of the business and for the conduct of the affairs
of the Corporation, and in further definition, limitation and regulation of the
powers of the Corporation, of its directors and of its stockholders or any class
thereof, as the case may be, it is further provided that:

          (1)  The management of the business and the conduct of the affairs of
the Corporation shall be vested in its Board of Directors. The number of
directors which shall constitute the whole Board of Directors shall be fixed
exclusively by one or more resolutions adopted by the Board of Directors.

          (2)  Subject to the rights of the holders of any series of Preferred
Stock to elect additional directors under specified circumstances, and to any
restrictions or limitations of applicable law, following the closing of the
initial public offering pursuant to an effective registration statement under
the Securities Act of 1933, as amended, covering the offer and sale of Common
Stock to the public (the "Initial Public Offering"), the directors shall be
divided into three classes designated as Class I, Class II and Class III,
respectively. Directors shall be assigned to each class in accordance with a
resolution or resolutions adopted by the Board of Directors. At the first annual
meeting of stockholders following the closing of the Initial Public Offering,
the term of office of the Class I directors shall expire and Class I directors
shall be elected for a full term of three years. At the second annual meeting of
stockholders following the Closing of the Initial Public Offering, the term of
office of the Class II directors shall expire and Class II directors shall be
elected for a full term of three years. At the third annual meeting of
stockholders following the Closing of the Initial Public Offering, the term of
office of the Class III directors shall expire and Class III directors shall be
elected for a full term of three years. At each succeeding annual meeting of
stockholders, directors shall be elected for a full term of three years to
succeed the directors of the class whose terms expire at such annual meeting.

     Notwithstanding the foregoing provisions of this Article, each director
shall serve until his successor is duly elected and qualified or until his
death, resignation or removal. No decrease in the number of directors
constituting the Board of Directors shall shorten the term of any incumbent
director.

          (3)  Subject to the rights of the holders of any series of Preferred
Stock, the Board of Directors or any individual director may be removed from
office at any time (i) with cause by the affirmative vote of the holders of a
majority of the voting power of all the then-outstanding shares of voting stock
of the Corporation, entitled to vote at an election of directors (the "Voting
Stock") or (ii) without cause by the affirmative vote of the holders of at least
sixty-six and two-thirds percent (66 2/3%) of the voting power of all the then-
outstanding shares of the Voting Stock.

          (4)  Subject to the rights of the holders of any series of Preferred
Stock, any vacancies on the Board of Directors resulting from death,
resignation, disqualification, removal or other causes and any newly created
directorships resulting from any increase in the number of

                                       2
<PAGE>

directors, shall, unless the Board of Directors determines by resolution that
any such vacancies or newly created directorships shall be filled by the
stockholders, except as otherwise provided by law, be filled only by the
affirmative vote of a majority of the directors then in office, even though less
than a quorum of the Board of Directors, and not by the stockholders. Any
director elected in accordance with the preceding sentence shall hold office for
the remainder of the full term of the director for which the vacancy was created
or occurred and until such director's successor shall have been elected and
qualified.

          (5)  In the event that Section 2115(a) of the California Corporations
Code is applicable to this corporation, then the following shall apply:

               (a)  Every stockholder entitled to vote in any election of
directors of this corporation may cumulate such stockholder's votes and give one
candidate a number of votes equal to the number of directors to be elected
multiplied by the number of votes to which the stockholder's shares are
otherwise entitled, or distribute the stockholder's votes on the same principle
among as many candidates as such stockholder thinks fit;

               (b)  No stockholder, however, may cumulate such stockholder's
votes for one or more candidates unless (i) the names of such candidates have
been properly placed in nomination, in accordance with the Bylaws of the
corporation, prior to the voting, (ii) the stockholder has given advance notice
to the corporation of the intention to cumulative votes pursuant to the Bylaws,
and (iii) the stockholder has given proper notice to the other stockholders at
the meeting, prior to voting, of such stockholder's intention to cumulate such
stockholder's votes; and

               (c)  If any stockholder has given proper notice, all stockholders
may cumulate their votes for any candidates who have been properly placed in
nomination. The candidates receiving the highest number of votes of the shares
entitled to be voted for them up to the number of directors to be elected by
such shares shall be declared elected.

     B.   (1)  Subject to paragraph (h) of Section 43 of the Bylaws, the Bylaws
may be altered or amended or new Bylaws adopted by the affirmative vote of at
least sixty-six and two-thirds percent (66-2/3%) of the voting power of all of
the then-outstanding shares of the Voting Stock. The Board of Directors shall
also have the power to adopt, amend, or repeal Bylaws.

          (2)  The directors of the Corporation need not be elected by written
ballot unless the Bylaws so provide.

          (3)  No action shall be taken by the stockholders of the Corporation
except at an annual or special meeting of stockholders called in accordance with
the Bylaws and following the closing of the Initial Public Offering no action
shall be taken by the stockholders by written consent.

          (4)  Advance notice of stockholder nominations for the election of
directors and of business to be brought by stockholders before any meeting of
the stockholders of the Corporation shall be given in the manner provided in the
Bylaws of the Corporation.

                                       3
<PAGE>

                                      VI.

     A.   A director of the Corporation shall not be personally liable to the
Corporation or its stockholders for monetary damages for any breach of fiduciary
duty as a director, except for liability (i) for any breach of the director's
duty of loyalty to the Corporation or its stockholders, (ii) for acts or
omissions not in good faith or which involve intentional misconduct or a knowing
violation of law, (iii) under Section 174 of the Delaware General Corporation
Law, or (iv) for any transaction from which the director derived an improper
personal benefit.  If the Delaware General Corporation Law is amended after
approval by the stockholders of this Article to authorize corporate action
further eliminating or limiting the personal liability of directors, then the
liability of a director shall be eliminated or limited to the fullest extent
permitted by the Delaware General Corporation Law, as so amended.

     B.   Any repeal or modification of this Article VI shall be prospective and
shall not affect the rights under this Article VI in effect at the time of the
alleged occurrence of any act or omission to act giving rise to liability or
indemnification.

                                     VII.

     A.   The Corporation reserves the right to amend, alter, change or repeal
any provision contained in this Certificate of Incorporation, in the manner now
or hereafter prescribed by statute, except as provided in paragraph B. of this
Article VII, and all rights conferred upon the stockholders herein are granted
subject to this reservation.

     B.   Notwithstanding any other provisions of this Certificate of
Incorporation or any provision of law which might otherwise permit a lesser vote
or no vote, but in addition to any affirmative vote of the holders of any
particular class or series of the Voting Stock required by law, this Certificate
of Incorporation or any Preferred Stock Designation, the affirmative vote of the
holders of at least sixty-six and two-thirds percent (66-2/3%) of the voting
power of all of the then-outstanding shares of the Voting Stock, voting together
as a single class, shall be required to alter, amend or repeal Articles V, VI
and VII.

                                       4
<PAGE>

                          CERTIFICATE OF AMENDMENT TO

             AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF

                      TERAYON COMMUNICATION SYSTEMS, INC.

     Terayon Communication Systems, Inc., a corporation organized and existing
under and by virtue of the Delaware General Corporation Law (the "Company"),
does hereby certify:

     First:   The name of the Company is Terayon Communication Systems, Inc.

     Second:  The original certificate of incorporation of this Company was
filed with the Secretary of State of the State of Delaware on June 12, 1998
under the name of Terayon Merger Corporation.

     Third:   The Board of Directors of the Company, acting in accordance with
the provisions of Sections 141 and 242 of the Delaware General Corporation Law,
adopted resolutions amending the Company's Amended and Restated Certificate of
Incorporation as follows:

          The first paragraph of Article IV shall be amended and restated to
read in its entirety as follows:

          "This Corporation is authorized to issue two classes of stock to be
     designated, respectively, "Common Stock" and "Preferred Stock."  The total
     number of shares which the corporation is authorized to issue is Two
     Hundred Five Million (205,000,000) shares.  Two Hundred Million
     (200,000,000) shares shall be Common Stock, each having a par value of one
     tenth of one cent ($.001).  Five Million (5,000,000) shares shall be
     Preferred Stock, each having a par value of one tenth of one cent ($.001)."

     Fourth:  Thereafter, pursuant to a resolution of the Board of Directors,
this Certificate of Amendment was submitted to the stockholders of the Company
for their approval, and was duly adopted in accordance with the provisions of
Section 242 of the Delaware Corporation Law.

     In Witness Whereof, the undersigned has signed this Certificate of
Amendment this 20th day of April 2000, and hereby affirms and acknowledges under
penalty of perjury that the filing of this Certificate of Amendment is the act
and deed of Terayon Communication Systems, Inc.

                                   Terayon Communication Systems, Inc.

                                   By: /s/ Zaki Rakib
                                       _____________________________
                                           Zaki Rakib
                                           Chief Executive Officer
<PAGE>

                          CERTIFICATE OF DESIGNATION

                                      OF

                 SERIES A JUNIOR PARTICIPATING PREFERRED STOCK

                        (Pursuant to Section 151 of the
                       Delaware General Corporation Law)

     Terayon Communication Systems, Inc., a corporation organized and existing
under the General Corporation Law of the State of Delaware (hereinafter called
the "Company"), hereby certifies that the following resolution was adopted by
the Board of Directors of the Corporation as required by Section 151 of the
General Corporation Law at a meeting duly called and held on February 6, 2001:

               Resolved, that pursuant to the authority granted to and vested in
          the Board of Directors of the Company in accordance with the
          provisions of its Amended and Restated Certificate of Incorporation,
          as amended (the "Certificate of Incorporation"), the Board of
          Directors hereby creates a series of Preferred Stock, par value $.001
          per share, of the Company and hereby states the designation and number
          of shares, and fixes the relative designations and the powers,
          preferences and rights, and the qualifications, limitations and
          restrictions thereof (in addition to the provisions set forth in the
          Certificate of Incorporation of the Company, which are applicable to
          the Preferred Stock of all classes and series), as follows:

Series A Junior Participating Preferred Stock:

     Section 1.  Designation and Amount. Two million (2,000,000) shares of
Preferred Stock, $.001 par value, are designated "Series A Junior Participating
Preferred Stock" with the designations and the powers, preferences and rights,
and the qualifications, limitations and restrictions specified herein (the
"Junior Preferred Stock"). Such number of shares may be increased or decreased
by resolution of the Board of Directors; provided, that no decrease shall reduce
the number of shares of Junior Preferred Stock to a number less than the number
of shares then outstanding plus the number of shares reserved for issuance upon
the exercise of outstanding options, rights or warrants or upon the conversion
of any outstanding securities issued by the Company convertible into Junior
Preferred Stock.

<PAGE>

     Section 2.  Dividends and Distributions.

          (A)  Subject to the rights of the holders of any shares of any series
of Preferred Stock (or any similar stock) ranking prior and superior to the
Junior Preferred Stock with respect to dividends, the holders of shares of
Junior Preferred Stock, in preference to the holders of Common Stock, par value
$.001 per share (the "Common Stock"), of the Company, and of any other junior
stock, shall be entitled to receive, when, as and if declared by the Board of
Directors out of funds legally available for the purpose, quarterly dividends
payable in cash on the first day of April, July, October and January in each
year (each such date being referred to herein as a "Quarterly Dividend Payment
Date"), commencing on the first Quarterly Dividend Payment Date after the first
issuance of a share or fraction of a share of Junior Preferred Stock, in an
amount per share (rounded to the nearest cent) equal to the greater of (a) $l.00
or (b) subject to the provision for adjustment hereinafter set forth, 100 times
the aggregate per share amount of all cash dividends, and 100 times the
aggregate per share amount (payable in kind) of all non-cash dividends or other
distributions, other than a dividend payable in shares of Common Stock or a
subdivision of the outstanding shares of Common Stock (by reclassification or
otherwise), declared on the Common Stock since the immediately preceding
Quarterly Dividend Payment Date or, with respect to the first Quarterly Dividend
Payment Date, since the first issuance of any share or fraction of a share of
Junior Preferred Stock. In the event the Company shall at any time declare or
pay any dividend on the Common Stock payable in shares of Common Stock, or
effect a subdivision or combination or consolidation of the outstanding shares
of Common Stock (by reclassification or otherwise than by payment of a dividend
in shares of Common Stock) into a greater or lesser number of shares of Common
Stock, then in each such case the amount to which holders of shares of Junior
Preferred Stock were entitled immediately prior to such event under clause (b)
of the preceding sentence shall be adjusted by multiplying such amount by a
fraction, the numerator of which is the number of shares of Common Stock
outstanding immediately after such event and the denominator of which is the
number of shares of Common Stock that were outstanding immediately prior to such
event.

          (B)  The Company shall declare a dividend or distribution on the
Junior Preferred Stock as provided in paragraph (A) of this Section immediately
after it declares a dividend or distribution on the Common Stock (other than a
dividend payable in shares of Common Stock); provided, that in the event no
dividend or distribution shall have been declared on the Common Stock during the
period between any Quarterly Dividend Payment Date and the next subsequent
Quarterly Dividend Payment Date, a dividend of $1.00 per share on the Junior
Preferred Stock shall nevertheless be payable on such subsequent Quarterly
Dividend Payment Date.

          (C)  Dividends shall begin to accrue and be cumulative on outstanding
shares of Junior Preferred Stock from the Quarterly Dividend Payment Date next
preceding the date of issue of such shares, unless the date of issue of such
shares is prior to the record date for the first Quarterly Dividend Payment
Date, in which case dividends on such shares shall begin to accrue from the date
of issue of such shares, or unless the date of issue is a Quarterly Dividend
Payment Date or is a date after the record date for the determination of holders
of shares of Junior Preferred Stock entitled to receive a quarterly dividend and
before such Quarterly Dividend Payment Date, in either of which events such
dividends shall begin to accrue and be cumulative from such Quarterly Dividend
Payment Date. Accrued but unpaid dividends shall not bear
<PAGE>

interest. Dividends paid on the shares of Junior Preferred Stock in an amount
less than the total amount of such dividends at the time accrued and payable on
such shares shall be allocated pro rata on a share-by-share basis among all such
shares at the time outstanding. The Board of Directors may fix a record date for
the determination of holders of shares of Junior Preferred Stock entitled to
receive payment of a dividend or distribution declared thereon, which record
date shall be not more than 60 days prior to the date fixed for the payment
thereof.

     Section 3.  Voting Rights.  The holders of shares of Junior Preferred Stock
shall have the following voting rights:

          (A)  Subject to the provision for adjustment hereinafter set forth,
each share of Junior Preferred Stock shall entitle the holder thereof to 100
votes on all matters submitted to a vote of the stockholders of the Company. In
the event the Company shall at any time declare or pay any dividend on the
Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the number of votes per share to which holders of shares of Junior
Preferred Stock were entitled immediately prior to such event shall be adjusted
by multiplying such number by a fraction, the numerator of which is the number
of shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

          (B)  Except as otherwise provided herein, in any other Certificate of
Designation creating a series of Preferred Stock or any similar stock, or by
law, the holders of shares of Junior Preferred Stock and the holders of shares
of Common Stock and any other capital stock of the Company having general voting
rights shall vote together as one class on all matters submitted to a vote of
stockholders of the Company.

          (C)  Except as set forth herein, or as otherwise provided by law,
holders of Junior Preferred Stock shall have no special voting rights and their
consent shall not be required (except to the extent they are entitled to vote
with holders of Common Stock as set forth herein) for taking any corporate
action.

     Section 4.  Certain Restrictions.

          (A)  Whenever quarterly dividends or other dividends or distributions
payable on the Junior Preferred Stock as provided in Section 2 are in arrears,
thereafter and until all accrued and unpaid dividends and distributions, whether
or not declared, on shares of Junior Preferred Stock outstanding shall have been
paid in full, the Company shall not:

               (i)  declare or pay dividends, or make any other distributions,
on any shares of stock ranking junior (either as to dividends or upon
liquidation, dissolution or winding up) to the Junior Preferred Stock;

               (ii) declare or pay dividends, or make any other distributions,
on any shares of stock ranking on a parity (either as to dividends or upon
liquidation, dissolution or winding up) with the Junior Preferred Stock, except
dividends paid ratably on the Junior
<PAGE>

Preferred Stock and all such parity stock on which dividends are payable or in
arrears in proportion to the total amounts to which the holders of all such
shares are then entitled;

               (iii)  redeem or purchase or otherwise acquire for consideration
shares of any stock ranking junior (either as to dividends or upon liquidation,
dissolution or winding up) to the Junior Preferred Stock, provided that the
Company may at any time redeem, purchase or otherwise acquire shares of any such
junior stock in exchange for shares of any stock of the Company ranking junior
(either as to dividends or upon dissolution, liquidation or winding up) to the
Junior Preferred Stock; or

               (iv)   redeem or purchase or otherwise acquire for consideration
any shares of Junior Preferred Stock, or any shares of stock ranking on a parity
(either as to dividends or upon liquidation, dissolution or winding up) with the
Junior Preferred Stock, except in accordance with a purchase offer made in
writing or by publication (as determined by the Board of Directors) to all
holders of such shares upon such terms as the Board of Directors, after
consideration of the respective annual dividend rates and other relative rights
and preferences of the respective series and classes, shall determine in good
faith will result in fair and equitable treatment among the respective series or
classes.

          (B)  The Company shall not permit any subsidiary of the Company to
purchase or otherwise acquire for consideration any shares of stock of the
Company unless the Company could, under paragraph (A) of this Section 4,
purchase or otherwise acquire such shares at such time and in such manner.

     Section 5. Reacquired Shares. Any shares of Junior Preferred Stock
purchased or otherwise acquired by the Company in any manner whatsoever shall be
retired and cancelled promptly after the acquisition thereof. All such shares
shall upon their cancellation become authorized but unissued shares of Preferred
Stock and may be reissued as part of a new series of Preferred Stock subject to
the conditions and restrictions on issuance set forth herein, in the Certificate
of Incorporation, or in any other Certificate of Designation creating a series
of Preferred Stock or any similar stock or as otherwise required by law.

     Section 6. Liquidation, Dissolution or Winding Up.  Upon any liquidation,
dissolution or winding up of the Company, no distribution shall be made (1) to
the holders of shares of stock ranking junior (either as to dividends or upon
liquidation, dissolution or winding up) to the Junior Preferred Stock unless,
prior thereto, the holders of shares of Junior Preferred Stock shall have
received $100 per share, plus an amount equal to accrued and unpaid dividends
and distributions thereon, whether or not declared, to the date of such payment,
provided that the holders of shares of Junior Preferred Stock shall be entitled
to receive an aggregate amount per share, subject to the provision for
adjustment hereinafter set forth, equal to 100 times the aggregate amount to be
distributed per share to holders of shares of Common Stock, or (2) to the
holders of shares of stock ranking on a parity (either as to dividends or upon
liquidation, dissolution or winding up) with the Junior Preferred Stock, except
distributions made ratably on the Junior Preferred Stock and all such parity
stock in proportion to the total amounts to which the holders of all such shares
are entitled upon such liquidation, dissolution or winding up.  In the event the
Company shall at any time declare or pay any dividend on the Common Stock
payable in shares of Common Stock, or effect a subdivision or combination or
consolidation of
<PAGE>

the outstanding shares of Common Stock (by reclassification or otherwise than by
payment of a dividend in shares of Common Stock) into a greater or lesser number
of shares of Common Stock, then in each such case the aggregate amount to which
holders of shares of Junior Preferred Stock were entitled immediately prior to
such event under the proviso in clause (1) of the preceding sentence shall be
adjusted by multiplying such amount by a fraction the numerator of which is the
number of shares of Common Stock outstanding immediately after such event and
the denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

     Section 7.  Consolidation, Merger, Etc. In case the Company shall enter
into any consolidation, merger, combination or other transaction in which the
shares of Common Stock are exchanged for or changed into other stock or
securities, cash and/or any other property, then in any such case each share of
Junior Preferred Stock shall at the same time be similarly exchanged or changed
into an amount per share, subject to the provision for adjustment hereinafter
set forth, equal to 100 times the aggregate amount of stock, securities, cash
and/or any other property (payable in kind), as the case may be, into which or
for which each share of Common Stock is changed or exchanged. In the event the
Company shall at any time declare or pay any dividend on the Common Stock
payable in shares of Common Stock, or effect a subdivision or combination or
consolidation of the outstanding shares of Common Stock (by reclassification or
otherwise than by payment of a dividend in shares of Common Stock) into a
greater or lesser number of shares of Common Stock, then in each such case the
amount set forth in the preceding sentence with respect to the exchange or
change of shares of Junior Preferred Stock shall be adjusted by multiplying such
amount by a fraction, the numerator of which is the number of shares of Common
Stock outstanding immediately after such event and the denominator of which is
the number of shares of Common Stock that were outstanding immediately prior to
such event.

     Section 8.  No Redemption. The shares of Junior Preferred Stock shall not
be redeemable.

     Section 9.  Rank. The Junior Preferred Stock shall rank, with respect to
the payment of dividends and the distribution of assets, junior to all series of
any other class of the Company's Preferred Stock.

     Section 10. Amendment. The Certificate of Incorporation of the Company
shall not be amended in any manner which would materially alter or change the
powers, preferences or special rights of the Junior Preferred Stock so as to
affect them adversely without the affirmative vote of the holders of at least
two-thirds of the outstanding shares of Junior Preferred Stock, voting together
as a single class.

               [remainder of this page left blank intentionally]



<PAGE>

    In Witness Whereof, the undersigned have executed this certificate as of
February 6, 2001.

                              /s/ Shlomo Rakib
                              __________________________________________
                              Shlomo Rakib
                              President


                              /s/ Zaki Rakib
                              __________________________________________
                              Zaki Rakib
                              Chief Executive Officer and Secretary