Document:

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                                                                     Exhibit 4.3

                          AMENDMENT TO RIGHTS AGREEMENT

     1.   General Background. In accordance with Section 27 of the Rights
          ------------------
Agreement between Bank Boston, N. A. (the "Rights Agent") and Power
Integrations, Inc. dated February 24, 1999 (the "Agreement"), the Rights Agent
and Power Integrations desire to amend the Agreement to appoint EquiServe Trust
Company, N .A.

     2.   Effectiveness. This Amendment shall be effective as of October 9, 2001
          -------------
(the "Amendment") and all defined terms and definitions in the Agreement shall
be the same in the Amendment except as specifically revised by the Amendment.

     3.   Revision. The section in the Agreement entitled "Change of Rights
          --------
Agent" is hereby deleted in its entirety and replaced with the following:

          Change of Rights Agent. The Rights Agent or any successor Rights Agent
          ----------------------
     may resign and be discharged from its duties under this Agreement upon 30
     days' notice in writing mailed to the Company and to each transfer agent of
     the Common Shares or Preferred shares by registered or certified mail and
     to the holders of the Right Certificates by first-class mail. The Company
     may remove the Rights Agent or any successor Rights Agent upon 30 days'
     notice in writing mailed to the Rights Agent or successor Rights Agent, as
     the case may be, and to each transfer agent of the Common Shares or
     Preferred Shares by registered or certified mail, and to the holders of the
     Right Certificates by first-class mail. If the Rights Agent shall resign or
     be removed or shall otherwise become incapable of acting, the Company shall
     appoint a successor to the Rights Agent. If the Company shall fail to make
     such appointment within a period of 30 days after giving notice of such
     removal or after it has been notified in writing of such resignation or
     incapacity by the resigning or incapacitated rights Agent or by the holder
     of a Right Certificate (who shall, with such notice, submit such holder's
     Right Certificate for inspection by the company), then the registered
     holder of any Right Certificate may apply to any court of competent
     jurisdiction for the appointment of a new Rights Agent. Any successor
     Rights Agent, whether appointed by the Company or by such a court, shall be
     a corporation or trust company organized and doing business under the laws
     of the United States, in good standing, which is authorized under such laws
     to exercise corporate trust or stock transfer powers and is subject to
     supervision or examination by federal or state authority and which has
     individually or combined with an affiliate at the time of its appointment
     as Rights Agent a combined capital and surplus of at least $100 million
     dollars. After appointment, the successor Rights Agent shall be vested with
     the same powers, rights, duties and responsibilities as if it had been
     originally named as Rights Agent without further act or deed; but the
     predecessor Rights Agent shall deliver and transfer to the successor Rights
     Agent any property at the time held by it hereunder, and execute and
     deliver any further assurance, conveyance, act or deed necessary for the
     purpose. Not later than the effective date of any such appointment the
     Company shall file notice thereof in writing with the predecessor Rights
     Agent and each transfer agent of the Common Shares or Preferred Shares, and
     mail a notice thereof in writing to the registered holders of the Right
     Certificates. Failure to give any notice provided for in this Section 21,
     however, or any defect therein, shall not affect the legality or validity
     of the

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     resignation or removal of the Rights Agent or the appointment of the
     successor Rights Agent, as the case may be.

     4.   Except as amended hereby, the Agreement and all schedules or exhibits
thereto shall remain in full force and effect.

     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
executed in their names and on their behalf by and through their duly authorized
officers, as of this 9th day of October, 2001.

Power Integrations, Inc.                        Bank Boston, N.A.

/s/ Robert J. Lelieur                           /s/ Carol Mulvey-Eori
--------------------------------                --------------------------------
By: Robert J. Lelieur                           By:    Carol Mulvey-Eori
Title: Director of Finance                      Title: Managing Director
                                                       Client Administration

                                                EquiServe Trust Company, N.A.

                                                /s/ Carol Mulvey-Eori
                                                --------------------------------
                                                By:    Carol Mulvey-Eori
                                                Title: Managing Director
                                                       Client Administration

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                                                                   EXHIBIT 10.18

Leasing agreement

Second Floor, Sanwa Building

Period of leasing agreement
         from June 11, 2001
         until June 10, 2003

Lessor: Sanwa Radiator, Co. Ltd.
Lessee: Natus Japan, Co. Ltd.

office

page 1

Contract for leasing of space

The lessor, Sanwa Radiator, Co. Ltd. (hereinafter called the "lessor" ), and the
lessee, Natus Japan, Co. Ltd. (hereinafter called "the lessee"), hereby enter
into a leasing agreement in accordance with the following conditions.

Article Number One (Announcement of leased space)
The lessor, the owner of the leased space described elsewhere (hereinafter
called the "leased space"), will lease this space to the lessee, who has leased
it.

Article Number Two (Purpose of use)
The lessee will use the leased space only for the purpose of running an office,
and will not use the space for any other purposes.

Article Number Three (Period of lease/Notice of termination of lease/Period of
lease renewal)
(1.) The period of this lease extends from June 10, 2001 until June 11, 2003, a
period of two years.
(2.) When either the lessor or lessee has decided to end this contract at the
end of the period of this lease, advance notice must be given to the other party
six months prior to the end of the leasing period, in accordance with this
document.
(3.) In a case where either the lessor or lessee does not provide notice as
described in the previous item to the other party six months prior to the end of
the leasing period, this contract will be extended for an additional two years.
After this, the end of the leasing period will be handled in the same manner.

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Article Number Four (Rental fees)
The monthly rental fees shall be 1,315,625 yen, and the lessee will deliver or
send payment to the lessor or its designated representative the rental fees for
the following month by the last day of the preceding month. However, the rental
fees for a period that is less than a full month shall be determined by
calculating the pro-rated payment for the number of days in that period.

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Article Number Five (Responsibility for various expenses)
The lessee shall be responsible for the various expenses laid out in each of the
items that follow, and payment for these various expenses shall be delivered to
or payment shall be sent to the lessor or its designated representative by the
last day of each month.
1. Monthly management fees in the sum of 315,750 yen (payment for the following
month shall be made by the last day of the current month)
2. Charges for gas, water, and electricity usage (including monthly base
charges) and heating and cooling expenses
3. Installation charges and activation fees related to fixtures and facilities
specially requested by the lessee, and charges for the use of the same
4. Among the shared expenditures from usage that benefit the lessee along with
other lessees, expenses set by the lessor as the lessee's share of the financial
responsibility

Article Number Six (Adjustment of rental fees)
In response to general fluctuations in prices, increases in public levies and
taxes on land and buildings, or in comparison to other rental fees in the local
area, when it has been determined that the rental fees in Article Four and the
group expenditures in Article Six Item 1 are insufficient, even during the
period of the lease agreement, these fees can be adjusted based on discussion
between the lessor and lessee.

Article Number Seven (Prohibitions)
The lessee and its employees shall not carry out activities to which the
following items apply.
1. Activities that interfere with the business operations or administration of
the lessor or other lessees
2. Transfer and storage of materials in the building or its vicinity that may
have explosive or flammable properties, or other materials that are dangerous,
unclean, malodorous or unsightly
3. Entry into the building of animals, or the feeding and care of animals inside
the building

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4. Cigarette butts and other flammable paper and trash materials that could
pollute the building shall be disposed of only in the locations designated by
the lessor
5. Cooking and sleeping overnight inside the building
6. Other activities that the lessor has posted as being prohibited for the
purpose of maintaining the safety, attractiveness, and quality of maintenance
and management of the building

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Article Number Eight (Limitations)
At times when the lessee proposes to carry out activities to which the following
items apply, prior approval must be obtained in advance from the lessor in
writing by those who intend to carry out these activities or their workers;
expenses shall be borne by the lessee.
1. Renovation of the leased spaced, partitioning of rooms, and other various
fixtures and facilities such as new installations, additions, removal or other
changes in the facilities
2. The new installation, addition, changes to or removal of wiring, piping or
equipment for electric lights, electric power, telephone, gas, water, or changes
in the capacity of the same
3. The installation or removal of safes, steel cabinets or other heavy items
4. The installation of signboards or other public display boards inside the
building, on the roof, in the vicinity of the building or in the glass windows;
or the installation, posting or writing of advertisements, signs or warning
notices

Article Number Nine (Responsibility for notification)
In cases when the lessee has or anticipates the need for repairs to the leased
space and partitions that the lessor owns, or other facilities in the building,
or in cases when there are locations that require equipment for the prevention
of disasters or accidents, immediate notice must be given to the lessor.

Article Number Ten (Prohibition of transference of leasing rights)
The lessee is prohibited from transferring the right to leasing of the leased
space to a third party. However, in cases where the third party is confirmed as
the general successor of the lessee through the transfer of the company's
business operations or partnership or due to some other arrangement, and the
lessor has approved the agreement in accordance in written form, no such
restrictions will be imposed.

Article Number Eleven (Prohibition of subletting)
The lessee may not transfer the lease either in part or in full to a third
party, may not offer continuous use, or use the space in conjunction with a
third party, or

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display the name of any operations in this space other than that of the lessee.
However, this restriction does not apply in cases where the lessor has provided
consent in writing.

Article Number Twelve (Entering the leased space for inspections)
At times when there is a need for maintenance, cleaning, protection from
robbery, protection from fire, rescue, or emergency measures, the lessor or its
employees may enter the leased space for such purposes, carry out the inspection
and determine the appropriate measure to be taken.

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Article Number Thirteen (Compensation for damages)
In cases when the lessee or its agents, employees, hired workers or others
associated with the lessee have, either intentionally or by accident, caused
damage to the lessor, other lessees or other third parties, the lessee shall
provide full compensation.

Article Number Fourteen (Exemptions)
When due to theft or disasters such as earthquake, fire, or flooding that are
beyond the control of the lessor, losses incurred by the lessee shall not be the
responsibility of the lessor.

Article Number Fifteen (Deposit)
(1.) In order to provide security for the execution of the duties based on this
contract, the lessee will pay a security deposit of 13,156,250 yen to the lessor
as outlined below. The deposit will not accrue interest.
(2.) In cases when the lessee is late in making payment of rent or other
expenses, or when the lessor has suffered losses in taking responsibility for
the financial obligations based on this contract, the lessor may, as a matter of
course, appropriate the deposit money as compensation.
(3.) Within 7 days of receiving notice of the appropriation of money in cases
such as that described in the previous item, the lessee will supplement the
amount that is in arrears until it reaches the amount of the deposit money in
item 1 above.
(4.) During the period of this lease, the lessee may not use the deposit money
to pay rental fee payments or to fulfill other obligations.
(5.) The lessee is not permitted to transfer the right to claim the return of
the deposit money to a third party, or to use it as collateral for its
obligations.

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(6.) If the lessee has fulfilled all of the obligations outlined in this
agreement, the money used as a security deposit will be returned as outlined in
the items below.

     1. If the lessor has proposed dissolution of the contract, the money will
be returned at the time the lessee has completely vacated the premises.
     2. If the lessee has proposed dissolution of the contract, the money will
be returned within one month from the day the dissolution of the contract goes
into effect. However, this is subject to the condition that the lessee has
completely vacated the premises by the end of the period the contract is in
force.
         3. In every case, whether effective under Article 16, dissolution of
the contract; Article 17, immediate dissolution of the contract; or Article 18,
completion of contract, the date that these occurred will be taken as the
starting point, and the money will be returned within one month from that date.
However, in these cases as well, the conditions in the previous item will apply.
         4. If less than one full year has passed since entering into this
agreement in cases of either dissolution of contract or completion of contract,
and if less than one full year has passed since entering into this agreement and
the deadline for returning the deposit money has arrived, irrespective of the
period set in item 2 for the redemption of the deposit, as a special exemption,
the period for redemption of the deposit shall be extended to the date at which
one full year has passed since entering into the agreement.
         5. Regardless of the period set in item three above for redemption of
the deposit, after the lessee has vacated the premises and the lessor has newly
rented said premises, when the new deposit money has been received, at that time
the lessee's deposit money will be returned.

Article Number Sixteen (Dissolution of contract)
The lessor, at the time when the lessee has performed or fulfilled the
activities outlined in each item below and there is no need for notification of
some sort, will immediately terminate this agreement, and will demand that the
premises be vacated if there is no dispute put forth by the lessee. In a case
when the lessor has been subject to damages, compensation for these damages can
be demanded from the lessee, and will be granted if the lessee does not dispute
the claim.

page 6

1. In cases when the application has been filled in falsely at the time of
move-in, or when move-in has been carried out incorrectly
2. In case when the rent or other obligations are two months or more in arrears
3. In cases when the leased space has been used for purposes other than those
described in Article 2
4. In cases when the exclusive possession of other lessees has been encroached
upon in some exceptional manner, or there is concern that such encroachment has
taken place

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5. In cases when trust has been lost in some exceptional manner, or
in cases when activities counter to the public welfare have taken place
6. In cases when the leased space has been vacated without permission, or in
cases when the leased space has not been used for a period of 30 continuous days
without obtaining permission
7. In cases when the lessee or its employees, either intentionally or by
accident, have damaged the leased space or building in some exceptional manner,
or have caused a fire to break out
8. In cases when due to other obligations, the company's assets have been
temporarily seized, temporarily disposed of, or in cases of extortion, or in
cases when the company has declared bankruptcy, compensation obligations, or
company revivification, or in other cases of declarations of company
re-organization or dissolution due to death or incompetence
9. In cases when the activities of the lessee or those occupying the same leased
space have caused the police to investigate the presence of stimulants or
prostitution, etc.
10. In cases when judged to be associated with violent groups or membership in
groups that carry out activities that disrupt the legal order
11. In cases when rough or violent language and actions are used, when there is
contentious behavior toward others without provocation, or when there are
attempts to disrupt the business, maintenance, or management operations related
to the building, when orderly proceedings are disrupted and these activities
cause the lessor to doubt the maintenance of good faith in dealings with the
lessee
12. In cases when any of the items in this contract or those supplemental to
this contract are violated

page 7

Article Number Seventeen (Notice of immediate contract dissolution)
In cases when unavoidable circumstances arise during the term of this lease and
this contract is to be dissolved, either the lessor or the lessee may provide
the other party with six months' prior notice in accordance with this document
and dissolve this contract. However, the lessee may, in lieu of notice, pay to
the lessor a dissolution fee in the amount of six months' rental fees and
thereby obtain immediate dissolution of the contract. In addition, in cases when
the lessee vacates the premises without giving notice in accordance with this
document, or in cases when due to debts of the lessee this contract is
dissolved, the lessee must bear the responsibility for payment of the same
contract dissolution fees.

Article Number Eighteen (Cancellation of contract)
In cases when due to natural disasters, earthquakes or other events that cannot
be controlled, the building is damaged or destroyed either in part or as a
whole,

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making it impossible to use the leased space, this contract will be ended
as a matter of course.

Article Number Nineteen (Restoration to original condition)
(1.) In cases when this contract is ended (including dissolution and termination
of the contract) the lessee must, by the deadline set by the lessor, restore the
partitioning of rooms installed in the space, and other facilities and fixtures
installed by the lessee; in cases when there are damaged or dirty places, the
lessee must restore the leased space to its original condition when returning
the premises to the lessor.
(2.) In cases when the leased space has not been restored to its original
condition by the time of the deadline set by the lessor, the lessor may take
measures to restore the space to its original condition at the lessee's expense.

Article Number Twenty (Measures regarding leftover equipment and goods after the
property is vacated)
In cases when there are materials and goods remaining inside the leased space
after the contract has ended and the premises have been vacated, the lessor may
dispose of these items as it deems fit, and the lessee is without recourse to
dispute these actions.

Article Number Twenty-one (Compensation for damages due to late evacuation)
In cases when the lessee has not vacated the premises at the time this contract
is ended, the lessee is responsible to pay damages to the lessor equal to double
the rental fees due for each day following the ending of the contract until the
premises are evacuated, as well as the various expenditures described in Article
6.

page 8

Article Number Twenty-two (Right to demand purchase of incidental fixtures)
Upon vacating the premises, and for that reason, irrespective of category, the
lessee shall not demand compensation from the lessor for redecoration of the
leased space or partitions between rooms, or for the purchase of other
incidental fixtures and facilities. Nor shall compensation be demanded for
necessary expenses incurred in connection with these renovations, nor money for
moving expenses, removal fees or money for the purchase of rights.

Article Number Twenty-three (Regulations inside the building)
The lessee agrees to abide by the rules of the building management established
elsewhere by the lessor.

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Article Number Twenty-four (Confirmation of representatives and examination of
this contract)
The representatives appointed by the lessor and lessee shall examine all of the
articles contained in this document, and announce that they, the lessor and
lessee, agree to adhere to the articles they have examined that constitute this
contract.

Article Number Twenty-five (Items not covered in regulations/items of
responsibility)
In cases when there is doubt about items that are not covered in this document
or with regard to the interpretation of these articles, the lessee and lessor
shall meet in good faith for discussion in order to clarify that interpretation.

Article Number Twenty-six (Jurisdiction over this agreement)
The lessor and lessee agree that any disputes arising in connection with this
contract shall fall under the jurisdiction of the first competent court in the
lessor's area of residence.

page 9

Article Number Twenty-seven (Items of special agreement)
(1.) With regard to the monthly rental fees and management fees, the lessee
shall bear responsibility for any additional consumption tax.
(2.) Address and information for electronic transfer of rental fees, management
fees, and consumption taxes.

Bank name: Fuji Ginko (Fuji Bank) Mita branch
Account number:
Name of client: Sanwa Radiator, Ltd.

In addition, the lessee shall be responsible to pay for the electronic transfer
fees.

Upon approval of this contract, two copies of the original contract shall be
made up, signed with personal seals affixed to it, and the lessee and lessor
shall each keep one copy of this document on file.

page 10

Lessor (landlord)
President, Eiji Watanabe
Sanwa Radiator, Co. Ltd.
24-21 Shiba 3-chome, Minato-ku, Tokyo

(seal affixed)

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Lessee (occupant)
President, Hiroshi Kasamatsu
Natus Japan, Co. Ltd.
3-22 Tora-no-mon, 2 Chome, Minato-ku, Tokyo

(seal affixed)

Representative
Kensetsu Daijin (1) No. 5907
Manager, Tomomi Mori
Sanwa Builds Co., Ltd.
Ueno Realtor Division
Hirokoji Kaikan 6F Ueno
Ueno 1-19-10 Daito-ku, Tokyo

(seal affixed)

Representative for trade in housing development and buildings
Registration number: Tokyo 99499
Tomomi Mori

(seal affixed)

page 11

Announcement of lease agreement

Address: 24-21 Shiba 3-chome, Minato-ku, Tokyo
Building name: Sanwa Building
Type of construction: Steel girders, with steel supported concrete construction,
a six-story building
Space being leased: second floor, 347.96 m2  (105 x 25 tsubo)

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