<PAGE>

                                                                   EXHIBIT 10.15

                                                          [California Net Lease]

                                 LEASE AGREEMENT

         THIS LEASE AGREEMENT is made this 23rd day of June, 2000, between
ProLogis Limited Partnership-I, a Delaware limited partnership, ("Landlord"),
and the Tenant named below.

TENANT:                       VOLTERRA SEMICONDUCTOR CORPORATION,
                              A DELAWARE CORPORATION

TENANT'S REPRESENTATIVE,      GREG HILDEBRAND
ADDRESS, AND PHONE NO.:       42840 CHRISTY STREET, SUITE 202
                              FREMONT, CA  94538
                              TEL:  (510) 657-9050

PREMISES:                     That portion of the Building, containing
                              approximately 20,000 rentable square feet, as
                              determined by Landlord and commonly known as 3839
                              SPINNAKER COURT as shown on Exhibit A.

PROJECT:                      SPINNAKER ONE

BUILDING:                     NO. 3

TENANT'S PROPORTIONATE SHARE
OF PROJECT:                   20.8%

TENANT'S PROPORTIONATE SHARE
OF BUILDING:                  100%

LEASE TERM:                   Beginning on the Commencement Date and
                              ending on the last day of the 84TH full
                              Calendar month thereafter.

COMMENCEMENT DATE:            UPON SUBSTANTIAL COMPLETION OF TENANT IMPROVEMENTS
                              AS DESCRIBED IN ADDENDUM II
<TABLE>
<S>                                 <C>                                 <C>                             <C>

INITIAL MONTHLY BASE RENT:    TWENTY NINE THOUSAND DOLLARS                                              $29,000.00

INITIAL ESTIMATED MONTHLY           1.     Common Area Charges:         $1,118.00
                                                                        ---------
OPERATING EXPENSE PAYMENTS:
(estimates only and subject to      2.     Taxes:                       $2,577.00
                                                                        ---------
adjustment to actual costs and
expenses according to the           3.     Insurance:                   $   58.00
provisions of this Lease)                                               ---------

                                    4.     Management Fee:              $  127.00
                                                                        ---------
INITIAL ESTIMATED MONTHLY
OPERATING EXPENSE PAYMENTS:                                                                             $ 3,880.00
                                                                                                        ==========
INITIAL MONTHLY BASE RENT AND
OPERATING EXPENSE PAYMENTS:                                                                             $32,880.00

SECURITY DEPOSIT:                   $ 34,000.00
                                    -----------

BROKER:                             JOHN BRACKETT/WAYNE MASCIA

ADDENDA:                            Addendum(s)  I, II, III, IV, V & VI                Exhibit(s) A, B, B-1 & C
</TABLE>

         1.       GRANTING CLAUSE. In consideration of the obligation of Tenant
to pay rent as herein provided and in consideration of the other terms,
covenants, and conditions hereof, Landlord leases to Tenant, and Tenant takes
from Landlord, the Premises, to have and to hold for the Lease Term, subject to
the terms, covenants and conditions of this Lease.

         2.       ACCEPTANCE OF PREMISES. Tenant shall accept the Premises in
its condition as of the Commencement Date, subject to all applicable laws,
ordinances, regulations, covenants and restrictions. Upon the Commencement Date,
Landlord shall deliver Tenant the plumbing, lighting, air conditioning, heating
and loading doors in good operating condition. Landlord has made no
representation or warranty as to the suitability of the Premises for the conduct
of Tenant's business, and Tenant waives any implied warranty that the Premises
are suitable for Tenant's intended purposes. Except as provided in Paragraph 10,
in no event shall Landlord have any obligation for any defects in the Premises
or any limitation on its use. The taking of possession of the Premises shall be
conclusive evidence that Tenant accepts the Premises and that the Premises were
in good condition at the time possession was taken except for items that are
Landlord's responsibility under Paragraph 10 and any punchlist items agreed to
in writing by Landlord and Tenant.

         3.       USE. The Premises shall be used only for the purpose of
research and development and general office uses and for such other lawful
purposes as may be incidental thereto.; Tenant

                                      -1-
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shall not conduct or give notice of any auction, liquidation, or going out of
business sale on the Premises. Tenant will use the Premises in a careful, safe
and proper manner and will not commit waste, overload the floor or structure of
the Premises or subject the Premises to use that would damage the Premises.
Tenant shall not permit any objectionable or unpleasant odors, smoke, dust, gas,
noise, or vibrations to emanate from the Premises, or take any other action that
would constitute a nuisance or would disturb, unreasonably interfere with, or
endanger Landlord or any tenants of the Project. Outside storage, including
without limitation, storage of trucks and other vehicles, is prohibited without
Landlord's prior written consent. Tenant, at its sole expense, shall use and
occupy the Premises in compliance with all laws, including, without limitation,
the Americans With Disabilities Act, orders, judgments, ordinances, regulations,
codes, directives, permits, licenses, covenants and restrictions now or
hereafter applicable to the Premises (collectively, "Legal Requirements"). The
Premises shall not be used as a place of public accommodation under the
Americans With Disabilities Act or similar state statutes or local ordinances or
any regulations promulgated thereunder, all as may be amended from time to time.
Tenant shall, at its expense, make any alterations or modifications, within or
without the Premises, that are required by Legal Requirements related to
Tenant's use or occupation of the Premises. Tenant will not use or permit the
Premises to be used for any purpose or in any manner that would void Tenant's or
Landlord's insurance, increase the insurance risk, or cause the disallowance of
any sprinkler credits. If any increase in the cost of any insurance on the
Premises or the Project is caused by Tenant's use or occupation of the Premises,
or because Tenant vacates the Premises, then Tenant shall pay the amount of such
increase to Landlord. Any occupation of the Premises by Tenant prior to the
Commencement Date shall be subject to all obligations of Tenant under this
Lease.

         4.       BASE RENT. Tenant shall pay Base Rent in the amount set forth
above. The first month's Base Rent, the Security Deposit, and the first monthly
installment of estimated Operating Expenses (as hereafter defined) shall be due
and payable on the date hereof, and Tenant promises to pay to Landlord in
advance, without demand, deduction or set-off, monthly installments of Base Rent
on or before the first day of each calendar month succeeding the Commencement
Date. Payments of Base Rent for any fractional calendar month shall be prorated.
All payments required to be made by Tenant to Landlord hereunder shall be
payable at such address as Landlord may specify from time to time by written
notice delivered in accordance herewith. The obligation of Tenant to pay Base
Rent and other sums to Landlord and the obligations of Landlord under this Lease
are independent obligations. Tenant shall have no right at any time to abate,
reduce, or set-off any rent due hereunder except as may be expressly provided in
this Lease. Tenant waives and releases all statutory liens and offset rights as
to rent. Tenant shall have no right at any time to abate, reduce, or set-off any
rent due hereunder except as may be expressly provided in this Lease. If Tenant
is delinquent in any monthly installment of Base Rent or of estimated Operating
Expenses for more than five (5) days after written notice (provided that
Landlord shall not be required to provide notice to monetary default more than
twice in any twelve (12) month period or more than three (3) times during the
term of this lease, as it may be extended), Tenant shall pay to Landlord on
demand a late charge equal to five (5) percent of such delinquent sum. The
provision for such late charge shall be in addition to all of Landlord's other
rights and remedies hereunder or at law and shall not be construed as a penalty.

         5.       SECURITY DEPOSIT. The Security Deposit shall be held by
Landlord as security for the performance of Tenant's obligations under this
Lease. The Security Deposit is not an advance rental deposit or a measure of
Landlord's damages in case of Tenant's default. Upon each occurrence of an Event
of Default (hereinafter defined), Landlord may use all or part of the Security
Deposit to pay delinquent payments due under this Lease, and the cost of any
damage, injury, expense or liability caused by such Event of Default, without
prejudice to any other remedy provided herein or provided by law. Tenant shall
pay Landlord on demand the amount that will restore the Security Deposit to its
original amount. Landlord's obligation respecting the Security Deposit is that
of a debtor, not a trustee; no interest shall accrue thereon. The Security
Deposit shall be the property of Landlord, but shall be paid to Tenant when
Tenant's obligations under this Lease have been completely fulfilled. Landlord
shall be released from any obligation with respect to the Security Deposit upon
transfer of this Lease and the Premises to a person or entity assuming
Landlord's obligations under this Paragraph 5.

         6.       OPERATING EXPENSE PAYMENTS. During each month of the Lease
Term, on the same date that Base Rent is due, Tenant shall pay Landlord an
amount equal to 1/12 of the annual cost, as estimated by Landlord from time to
time, of Tenant's Proportionate Share (hereinafter defined) of Operating
Expenses for the Project. Payments thereof for any fractional calendar month
shall be prorated. The term "Operating Expenses" means all costs and expenses
incurred by Landlord with respect to the ownership, maintenance, and operation
of the Project including, but not limited to costs of: Taxes (hereinafter
defined) and fees payable to tax consultants and attorneys for consultation and
contesting taxes; insurance; utilities; maintenance, repair and replacement of
all portions of the Project, including without limitation, paving and parking
areas, roads, roofs, alleys, and driveways, mowing, landscaping, exterior
painting, utility lines, heating, ventilation and air conditioning systems,
lighting, electrical systems and other mechanical and building systems; amounts
paid to contractors and subcontractors for work or services performed in
connection with any of the foregoing; charges or assessments of any association
to which the Project is subject; property management fees payable to a property
manager, including any affiliate of Landlord, or if there is no property
manager, an administration fee of 15 percent of Operating Expenses payable to
Landlord; security services, if any; trash collection, sweeping and removal; and
additions or alterations made by Landlord to the Project or the Building in
order to comply with Legal Requirements (other than those expressly required
herein to be made by Tenant) or that are appropriate to the continued operation
of the Project or the Building as a bulk warehouse facility in the market area,
provided that the cost of additions or alterations that are required to be
capitalized for federal income tax purposes shall be amortized on a straight
line basis over a period equal to the lesser of the useful life thereof for
federal income tax purposes or 10 years. Operating Expenses do not include (i)
costs, or expenses, depreciation or amortization for capital repairs and capital
replacements required to be made by Landlord under Paragraph 10 of this Lease,
(II) debt service under mortgages or ground rent under ground leases, (iii)
costs of

                                      -2-
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restoration to the extent of net insurance proceeds received by Landlord with
respect thereto, (IV) leasing commissions, or the costs of renovating space for
tenants., (v) costs attorney's fees other than those incurred for consultation
and contesting Taxes, (vi) advertising and promotional expenses, (vii) costs
incurred due to violations by Landlord of any governmental rule, (viii) wages or
other compensation paid to executive staff not directly related to the
maintenance, management and operation of the Project.

                  If Tenant's total payments of Operating Expenses for any year
are less than Tenant's Proportionate Share of actual Operating Expenses for such
year, then Tenant shall pay the difference to Landlord within 30 days after
demand, and if more, then Landlord shall retain such excess and credit it
against Tenant's next payments. Upon request Landlord shall provide Tenant with
a reasonably detailed statement of actual expenses and reconciliation's. For
purposes of calculating Tenant's Proportionate Share of Operating Expenses, a
year shall mean a calendar year except the first year, which shall begin on the
Commencement Date, and the last year, which shall end on the expiration of this
Lease. With respect to Operating Expenses which Landlord allocates to the entire
Project, Tenant's "Proportionate Share" shall be the percentage set forth on the
first page of this Lease as Tenant's Proportionate Share of the Project as
reasonably adjusted by Landlord in the future for changes in the physical size
of the Premises or the Project; and, with respect to Operating Expenses which
Landlord allocates only to the Building, Tenant's "Proportionate Share" shall be
the percentage set forth on the first page of this Lease as Tenant's
Proportionate Share of the Building as reasonably adjusted by Landlord in the
future for changes in the physical size of the Premises or the Building.
Landlord may equitably increase Tenant's Proportionate Share for any item of
expense or cost reimbursable by Tenant that relates to a repair, replacement, or
service that benefits only the Premises or only a portion of the Project or
Building that includes the Premises or that varies with occupancy or use. The
estimated Operating Expenses for the Premises set forth on the first page of
this Lease are only estimates, and Landlord makes no guaranty or warranty that
such estimates will be accurate.

         7.       UTILITIES. Tenant shall pay for all water, gas, electricity,
heat, light, power, telephone, sewer, sprinkler services, refuse and trash
collection, and other utilities and services used on the Premises, all
maintenance charges for utilities, and any storm sewer charges or other similar
charges for utilities imposed by any governmental entity or utility provider,
together with any taxes, penalties, surcharges or the like pertaining to
Tenant's use of the Premises. Landlord may cause at Tenant's expense any
utilities to be separately metered or charged directly to Tenant by the
provider. Tenant shall pay its share of all charges for jointly metered
utilities based upon consumption, as reasonably determined by Landlord. No
interruption or failure of utilities shall result in the termination of this
Lease or the abatement of rent. Tenant agrees to limit use of water and sewer
for normal restroom use.

         8.       TAXES.. Landlord shall pay all taxes, assessments and
governmental charges (collectively referred to as "Taxes") that accrue against
the Project during the Lease Term, which shall be included as part of the
Operating Expenses charged to Tenant. Landlord may contest by appropriate legal
proceedings the amount, validity, or application of any Taxes or liens thereof.
All capital levies or other taxes assessed or imposed on Landlord upon the rents
payable to Landlord under this Lease and any franchise tax, any excise,
transaction, sales or privilege tax, assessment, levy or charge measured by or
based, in whole or in part, upon such rents from the Premises and/or the Project
or any portion thereof shall be paid by Tenant to Landlord monthly in estimated
installments or upon demand, at the option of Landlord, as additional rent;
provided, however, in no event shall Tenant be liable for any net income taxes
imposed on Landlord unless such net income taxes are in substitution for any
Taxes payable hereunder. If any such tax or excise is levied or assessed
directly against Tenant, then Tenant shall be responsible for and shall pay the
same at such times and in such manner as the taxing authority shall require.
Tenant shall be liable for all taxes levied or assessed against any personal
property or fixtures placed in the Premises, whether levied or assessed against
Landlord or Tenant.

         9.       INSURANCE. Landlord shall maintain all risk property insurance
covering the full replacement cost of the Building. Landlord may, but is not
obligated to, maintain such other insurance and additional coverages as it may
deem necessary, including, but not limited to, commercial liability insurance
and rent loss insurance. All such insurance shall be included as part of the
Operating Expenses charged to Tenant. The Project or Building may be included in
a blanket policy (in which case the cost of such insurance allocable to the
Project or Building will be determined by Landlord based upon the insurer's cost
calculations). Tenant shall also reimburse Landlord for any increased premiums
or additional insurance which Landlord reasonably deems necessary as a result of
Tenant's use of the Premises.

                  Tenant, at its expense, shall maintain during the Lease Term:
all risk property insurance covering the full replacement cost of all property
and improvements installed or placed in the Premises by Tenant at Tenant's
expense; worker's compensation insurance with no less than the minimum limits
required by law; employer's liability insurance with such limits as required by
law; and commercial liability insurance, with a minimum limit of $1,000,000 per
occurrence and a minimum umbrella limit of $1,000,000, for a total minimum
combined general liability and umbrella limit of $2,000,000 (together with such
additional umbrella coverage as Landlord may reasonably require) for property
damage, personal injuries, or deaths of persons occurring in or about the
Premises. Landlord may from time to time require reasonable increases in any
such limits. The commercial liability policies shall name Landlord as an
additional insured, insure on an occurrence and not a claims-made basis, be
issued by insurance companies which are reasonably acceptable to Landlord, not
be cancelable unless 30 days' prior written notice shall have been given to
Landlord, contain a hostile fire endorsement and a contractual liability
endorsement and provide primary coverage to Landlord (any policy issued to
Landlord providing duplicate or similar coverage shall be deemed excess over
Tenant's policies). Such policies or certificates thereof shall be delivered to
Landlord by Tenant upon commencement of the Lease Term and upon each renewal of
said insurance.

                                      -3-
<PAGE>

                  The all risk property insurance obtained by Landlord and
Tenant shall include a waiver of subrogation by the insurers and all rights
based upon an assignment from its insured, against Landlord or Tenant, their
officers, directors, employees, managers, agents, invitees and contractors, in
connection with any loss or damage thereby insured against. Neither party nor
its officers, directors, employees, managers, agents, invitees or contractors
shall be liable to the other for loss or damage caused by any risk coverable by
all risk property insurance, and each party waives any claims against the other
party, and its officers, directors, employees, managers, agents, invitees and
contractors for such loss or damage. The failure of a party to insure its
property shall not void this waiver. Landlord and its agents, employees and
contractors shall not be liable for, and Tenant hereby waives all claims against
such parties for, business interruption and losses occasioned thereby sustained
by Tenant or any person claiming through Tenant resulting from any accident or
occurrence in or upon the Premises or the Project from any cause whatsoever,
including without limitation, damage caused in whole or in part, directly or
indirectly, by the negligence of Landlord or its agents, employees or
contractors.

         10.      LANDLORD'S REPAIRS. Landlord shall maintain, at its expense,
the structural soundness of the roof, foundation, and exterior walls of the
Building in good repair, reasonable wear and tear and uninsured losses and
damages caused by Tenant, its agents and contractors excluded. The term "walls"
as used in this Paragraph 10 shall not include windows, glass or plate glass,
doors or overhead doors, special store fronts, dock bumpers, dock plates or
levelers, or office entries. Tenant shall promptly give Landlord written notice
of any repair required by Landlord pursuant to this Paragraph 10, after which
Landlord shall have a reasonable opportunity to repair.

         11.      TENANT'S REPAIRS. Landlord, at Tenant's expense as provided in
Paragraph 6, shall maintain in good repair and condition the parking areas and
other common areas of the Building, including, but not limited to driveways,
alleys, landscape and grounds surrounding the Premises. Subject to Landlord's
obligation in Paragraph 10 and subject to Paragraphs 9 and 15, Tenant, at its
expense, shall repair, replace and maintain in good condition all portions of
the Premises and all areas, improvements and systems exclusively serving the
Premises including, without limitation, dock and loading areas, truck doors,
plumbing, water, and sewer lines up to points of common connection, fire
sprinklers and fire protection systems, entries, doors, ceilings and roof
membrane, windows, interior walls, and the interior side of demising walls, and
heating, ventilation and air conditioning systems. Such repair and replacements
include capital expenditures and repairs whose benefits may extend beyond the
Term. Heating, ventilation and air conditioning systems and other mechanical and
building systems serving the Premises shall be maintained at Tenant's expense
pursuant to maintenance service contracts entered into by Tenant or, at
Landlord's election, by Landlord. The scope of services and contractors under
such maintenance contracts shall be reasonably approved by Landlord. At
Landlord's request, Tenant shall enter into a joint maintenance agreement with
any railroad that services the Premises. If Tenant fails to perform any repair
or replacement for which it is responsible, Landlord may perform such work and
be reimbursed by Tenant within 10 days after demand therefor. Subject to
Paragraphs 9 and 15, Tenant shall bear the full cost of any repair or
replacement to any part of the Building or Project that results from damage
caused by Tenant, its agents, contractors, or invitees and any repair that
benefits only the Premises.

         12.      TENANT-MADE ALTERATIONS AND TRADE FIXTURES. Any alterations,
additions, or improvements in excess of $5,000.00 made by or on behalf of Tenant
to the Premises with the exception of the initial improvements ("Tenant-Made
Alterations") shall be subject to Landlord's prior written consent. Tenant shall
cause, at its expense, all Tenant-Made Alterations to comply with insurance
requirements and with Legal Requirements and shall construct at its expense any
alteration or modification required by Legal Requirements as a result of any
Tenant-Made Alterations. All Tenant-Made Alterations shall be constructed in a
good and workmanlike manner by contractors reasonably acceptable to Landlord and
only good grades of materials shall be used. All plans and specifications for
any Tenant-Made Alterations shall be submitted to Landlord for its approval.
Landlord may monitor construction of the Tenant-Made Alterations. Tenant shall
reimburse Landlord for its costs in reviewing plans and specifications and in
monitoring construction. Landlord's right to review plans and specifications and
to monitor construction shall be solely for its own benefit, and Landlord shall
have no duty to see that such plans and specifications or construction comply
with applicable laws, codes, rules and regulations. Tenant shall provide
Landlord with the identities and mailing addresses of all persons performing
work or supplying materials, prior to beginning such construction, and Landlord
may post on and about the Premises notices of non-responsibility pursuant to
applicable law. Tenant shall furnish security or make other arrangements
satisfactory to Landlord to assure payment for the completion of all work free
and clear of liens and shall provide certificates of insurance for worker's
compensation and other coverage in amounts and from an insurance company
satisfactory to Landlord protecting Landlord against liability for personal
injury or property damage during construction. Upon completion of any
Tenant-Made Alterations, Tenant shall deliver to Landlord sworn statements
setting forth the names of all contractors and subcontractors who did work on
the Tenant-Made Alterations and final lien waivers from all such contractors and
subcontractors. Upon surrender of the Premises, all Tenant-Made Alterations and
any leasehold improvements constructed by Landlord or Tenant shall remain on the
Premises as Landlord's property, except to the extent Landlord requires removal
at Tenant's expense of any such items or Landlord and Tenant have otherwise
agreed in writing in connection with Landlord's consent to any Tenant-Made
Alterations. Tenant shall repair any damage caused by such removal.

                  Tenant, at its own cost and expense and without Landlord's
prior approval, may erect such shelves, bins, machinery and trade fixtures
(collectively "Trade Fixtures") in the ordinary course of its business provided
that such items do not alter the basic character of the Premises, do not
overload or damage the Premises, and may be removed without injury to the
Premises, and the construction, erection, and installation thereof complies with
all

                                      -4-
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Legal Requirements and with Landlord's requirements set forth above. Tenant
shall remove its Trade Fixtures and shall repair any damage caused by such
removal.

         13.      SIGNS. Tenant shall not make any changes to the exterior of
the Premises, install any exterior lights, decorations, balloons, flags,
pennants, banners, or painting, or erect or install any signs, windows or door
lettering, placards, decorations, or advertising media of any type which can be
viewed from the exterior of the Premises, without Landlord's prior written
consent. Upon surrender or vacation of the Premises, Tenant shall have removed
all signs and repair, paint, and/or replace the building facia surface to which
its signs are attached. Tenant shall obtain all applicable governmental permits
and approvals for sign and exterior treatments. All signs, decorations,
advertising media, blinds, draperies and other window treatment or bars or other
security installations visible from outside the Premises shall be subject to
Landlord's approval and conform in all respects to Landlord's requirements.

         14.      PARKING. Tenant shall be entitled to park in common with other
tenants of the Project in those areas designated for nonreserved parking.
Landlord may allocate parking spaces among Tenant and other tenants in the
Project if Landlord determines that such parking facilities are becoming
crowded. Landlord shall not be responsible for enforcing Tenant's parking rights
against any third parties.

         15.      RESTORATION. If at any time during the Lease Term the Premises
are damaged by a fire or other casualty, Landlord shall notify Tenant within 60
days after such damage as to the amount of time Landlord reasonably estimates it
will take to restore the Premises. If the restoration time is estimated to
exceed 6 months, either Landlord or Tenant may elect to terminate this Lease
upon notice to the other party given no later than 30 days after Landlord's
notice. If neither party elects to terminate this Lease or if Landlord estimates
that restoration will take 6 months or less, then, subject to receipt of
sufficient insurance proceeds, Landlord shall promptly restore the Premises
excluding the improvements installed by Tenant or by Landlord and paid by
Tenant, subject to delays arising from the collection of insurance proceeds or
from Force Majeure events. Tenant at Tenant's expense shall promptly perform,
subject to delays arising from the collection of insurance proceeds, or from
Force Majeure events, all repairs or restoration not required to be done by
Landlord and shall promptly re-enter the Premises and commence doing business in
accordance with this Lease. Notwithstanding the foregoing, either party may
terminate this Lease if the Premises are damaged during the last year of the
Lease Term and Landlord reasonably estimates that it will take more than one
month to repair such damage. Tenant shall pay to Landlord with respect to any
damage to the Premises the amount of the commercially reasonable deductible
under Landlord's insurance policy within 10 days after presentment of Landlord's
invoice. If the damage involves the premises of other tenants, Tenant shall pay
the portion of the deductible that the cost of the restoration of the Premises
bears to the total cost of restoration, as determined by Landlord. Base Rent and
Operating Expenses shall be abated for the period of repair and restoration in
the proportion which the area of the Premises, if any, which is not usable by
Tenant bears to the total area of the Premises. Such abatement shall be the sole
remedy of Tenant, and except as provided herein, Tenant waives any right to
terminate the Lease by reason of damage or casualty loss.

         16.      CONDEMNATION. If any part of the Premises or the Project
should be taken for any public or quasi-public use under governmental law,
ordinance, or regulation, or by right of eminent domain, or by private purchase
in lieu thereof (a "Taking" or "Taken"), and the Taking would prevent or
materially interfere with Tenant's use of the Premises or in Landlord's judgment
would materially interfere with or impair its ownership or operation of the
Project, then upon written notice by Landlord this Lease shall terminate and
Base Rent shall be apportioned as of said date. If part of the Premises shall be
Taken, and this Lease is not terminated as provided above, the Base Rent payable
hereunder during the unexpired Lease Term shall be reduced to such extent as may
be fair and reasonable under the circumstances. In the event of any such Taking,
Landlord shall be entitled to receive the entire price or award from any such
Taking without any payment to Tenant, and Tenant hereby assigns to Landlord
Tenant's interest, if any, in such award. Tenant shall have the right, to the
extent that same shall not diminish Landlord's award, to make a separate claim
against the condemning authority (but not Landlord) for such compensation as may
be separately awarded or recoverable by Tenant for moving expenses and damage to
Tenant's Trade Fixtures, if a separate award for such items is made to Tenant.

         17.      ASSIGNMENT AND SUBLETTING. Without Landlord's prior written
consent, which Landlord shall not unreasonably withhold, Tenant shall not assign
this Lease or sublease the Premises or any part thereof or mortgage, pledge, or
hypothecate its leasehold interest or grant any concession or license within the
Premises and any attempt to do any of the foregoing shall be void and of no
effect. For purposes of this paragraph, a transfer of the ownership interests
controlling Tenant shall be deemed an assignment of this Lease unless such
ownership interests are publicly traded. Notwithstanding the above, Tenant may
assign or sublet the Premises, or any part thereof, to any entity controlling
Tenant, controlled by Tenant or under common control with Tenant (a "Tenant
Affiliate"), without the prior written consent of Landlord. Tenant shall
reimburse Landlord for all of Landlord's reasonable out-of-pocket expenses in
connection with any assignment or sublease. Upon Landlord's receipt of Tenant's
written notice of a desire to assign or sublet the Premises, or any part thereof
(other than to a Tenant Affiliate), Landlord may, by giving written notice to
Tenant within 30 days after receipt of Tenant's notice, terminate this Lease
with respect to the space described in Tenant's notice, as of the date specified
in Tenant's notice for the commencement of the proposed assignment or sublease.
If Landlord so terminates the Lease, Landlord may enter into a lease directly
with the proposed sublessee or assignee. Tenant may withdraw its notice to
sublease or assign by notifying Landlord within 10 days after Landlord has given
Tenant notice of such termination, in which case the Lease shall not terminate
but shall continue.

                                      -5-
<PAGE>

                  It shall be reasonable for the Landlord to withhold its
consent to any assignment or sublease in any of the following instances: (i) an
Event of Default has occurred and is continuing that would not be cured upon the
proposed sublease or assignment; (ii) the assignee or does not have a net worth
calculated according to generally accepted accounting principles at least equal
to the greater of the net worth of Tenant immediately prior to such assignment
or sublease or the net worth of the Tenant at the time it executed the Lease;
(iii) the intended use of the Premises by the assignee or sublessee is not
reasonably satisfactory to Landlord; (iv) the intended use of the Premises by
the assignee or sublessee would materially increase the pedestrian or vehicular
traffic to the Premises or the Project; (v) occupancy of the Premises by the
assignee or sublessee would, in Landlord's opinion, violate an agreement binding
upon Landlord or the Project with regard to the identity of tenants, usage in
the Project, or similar matters; (vi) the identity or business reputation of the
assignee or sublessee will, in the good faith judgment of Landlord, tend to
damage the goodwill or reputation of the Project; (vii) the assignment or sublet
is to another tenant in the Project and is at rates which are below those
charged by Landlord for vacant comparable space in the Project; (viii) in the
case of a sublease, the subtenant has not acknowledged that the Lease controls
over any inconsistent provision in the sublease; (ix) the proposed assignee or
sublessee is a governmental agency; or Tenant and Landlord acknowledge that
each of the foregoing criteria are reasonable as of the date of execution of
this Lease. The foregoing criteria shall not exclude any other reasonable basis
for Landlord to refuse its consent to such assignment or sublease. Any approved
assignment or sublease shall be expressly subject to the terms and conditions of
this Lease. Tenant shall provide to Landlord all information concerning the
assignee or sublessee as Landlord may request.

                  Notwithstanding any assignment or subletting, Tenant and any
guarantor or surety of Tenant's obligations under this Lease shall at all times
remain fully responsible and liable for the payment of the rent and for
compliance with all of Tenant's other obligations under this Lease (regardless
of whether Landlord's approval has been obtained for any such assignments or
sublettings). In the event that the rent due and payable by a sublessee or
assignee (or a combination of the rental payable under such sublease or
assignment plus any bonus or other consideration therefor or incident thereto)
exceeds the rental payable under this Lease, then Tenant shall be bound and
obligated to pay Landlord as additional rent hereunder 50% OF such excess rental
and other excess consideration within 10 days following receipt thereof by
Tenant.

                  If this Lease be assigned or if the Premises be subleased
(whether in whole or in part) or in the event of the mortgage, pledge, or
hypothecation of Tenant's leasehold interest or grant of any concession or
license within the Premises or if the Premises be occupied in whole or in part
by anyone other than Tenant, then upon a default by Tenant hereunder Landlord
may collect rent from the assignee, sublessee, mortgagee, pledgee, party to whom
the leasehold interest was hypothecated, concessionee or licensee or other
occupant and, except to the extent set forth in the preceding paragraph, apply
the amount collected to the next rent payable hereunder; and all such rentals
collected by Tenant shall be held in trust for Landlord and immediately
forwarded to Landlord. No such transaction or collection of rent or application
thereof by Landlord, however, shall be deemed a waiver of these provisions or a
release of Tenant from the further performance by Tenant of its covenants,
duties, or obligations hereunder.

         18.      INDEMNIFICATION. Except for the negligence of Landlord, its
agents, employees or contractors, and to the extent permitted by law, Tenant
agrees to indemnify, defend and hold harmless Landlord, and Landlord's agents,
employees and contractors, from and against any and all losses, liabilities,
damages, costs and expenses (including attorneys' fees) resulting from claims by
third parties for injuries to any person and damage to or theft or
misappropriation or loss of property occurring in or about the Project and
arising from the use and occupancy of the Premises or from any activity, work,
or thing done, permitted or suffered by Tenant in or about the Premises or due
to any other act or omission of Tenant, its subtenants, assignees, invitees,
employees, contractors and agents. The furnishing of insurance required
hereunder shall not be deemed to limit Tenant's obligations under this Paragraph
18.

         19.      INSPECTION AND ACCESS. Landlord and its agents,
representatives, and contractors may enter the Premises at any reasonable time
to inspect the Premises and to make such repairs as may be required or permitted
pursuant to this Lease and for any other business purpose. Landlord and
Landlord's representatives may enter the Premises during business hours for the
purpose of showing the Premises to prospective purchasers and, during the last
year of the Lease Term, to prospective tenants. Landlord may erect a suitable
sign on the Premises stating the Premises are available to let or that the
Project is available for sale. Landlord may grant easements, make public
dedications, designate common areas and create restrictions on or about the
Premises, provided that no such easement, dedication, designation or restriction
materially interferes with Tenant's use or occupancy of the Premises. At
Landlord's request, Tenant shall execute such instruments as may be necessary
for such easements, dedications or restrictions.

         20.      QUIET ENJOYMENT. If Tenant shall perform all of the covenants
and agreements herein required to be performed by Tenant, Tenant shall, subject
to the terms of this Lease, at all times during the Lease Term, have peaceful
and quiet enjoyment of the Premises against any person claiming by, through or
under Landlord.

         21.      SURRENDER. Upon termination of the Lease Term or earlier
termination of Tenant's right of possession, Tenant shall surrender the Premises
to Landlord in the same condition as received, broom clean, ordinary wear and
tear and casualty loss and condemnation covered by Paragraphs 15 and 16
excepted. Any Trade Fixtures, Tenant-Made Alterations and property not so
removed by Tenant as permitted or required herein shall be deemed abandoned and
may be stored, removed, and disposed of by Landlord at Tenant's expense, and
Tenant waives all claims against Landlord for any damages resulting from
Landlord's retention and disposition of such property. All obligations of Tenant
hereunder not fully performed as of the termination of the Lease Term shall

                                      -6-
<PAGE>

survive the termination of the Lease Term, including without limitation,
indemnity obligations, payment obligations with respect to Operating Expenses
and obligations concerning the condition and repair of the Premises.

         22.      HOLDING OVER. If Tenant retains possession of the Premises
after the termination of the Lease Term, unless otherwise agreed in writing,
such possession shall be subject to immediate termination by Landlord at any
time, and all of the other terms and provisions of this Lease (excluding any
expansion or renewal option or other similar right or option) shall be
applicable during such holdover period, except that Tenant shall pay Landlord
from time to time, upon demand, as Base Rent for the holdover period, an amount
equal to double the Base Rent in effect on the termination date, computed on a
monthly basis for each month or part thereof during such holding over. All other
payments shall continue under the terms of this Lease. In addition, Tenant shall
be liable for all damages incurred by Landlord as a result of such holding over.
No holding over by Tenant, whether with or without consent of Landlord, shall
operate to extend this Lease except as otherwise expressly provided, and this
Paragraph 22 shall not be construed as consent for Tenant to retain possession
of the Premises.

         23.      EVENTS OF DEFAULT. Each of the following events shall be an
event of default ("Event of Default") by Tenant under this Lease:

                  (i)      Tenant shall fail to pay any installment of Base Rent
         or any other payment required herein when due, and such failure shall
         continue for a period of 5 days from the date such payment was due.

                  (ii)     Tenant or any guarantor or surety of Tenant's
         obligations hereunder shall (A) make a general assignment for the
         benefit of creditors; (B) commence any case, proceeding or other action
         seeking to have an order for relief entered on its behalf as a debtor
         or to adjudicate it a bankrupt or insolvent, or seeking reorganization,
         arrangement, adjustment, liquidation, dissolution or composition of it
         or its debts or seeking appointment of a receiver, trustee, custodian
         or other similar official for it or for all or of any substantial part
         of its property (collectively a "proceeding for relief"); (C) become
         the subject of any proceeding for relief which is not dismissed within
         60 days of its filing or entry; or (D) die or suffer a legal disability
         (if Tenant, guarantor, or surety is an individual) or be dissolved or
         otherwise fail to maintain its legal existence (if Tenant, guarantor or
         surety is a corporation, partnership or other entity).

                  (iii)    Any insurance required to be maintained by Tenant
         pursuant to this Lease shall be cancelled or terminated or shall expire
         or shall be reduced or materially changed, except, in each case, as
         permitted in this Lease.

                  (iv)     Tenant shall not occupy or shall vacate the Premises
         or shall fail to continuously operate its business at the Premises for
         the permitted use set forth herein, whether or not Tenant is in
         monetary or other default under this Lease.

                  (v)      Tenant shall attempt or there shall occur any
         assignment, subleasing or other transfer of Tenant's interest in or
         with respect to this Lease except as otherwise permitted in this Lease.

                  (vi)     Tenant shall fail to discharge any lien placed upon
         the Premises in violation of this Lease within 30 days after any such
         lien or encumbrance is filed against the Premises.

                  (vii)    Tenant shall fail to comply with any provision of
         this Lease other than those specifically referred to in this Paragraph
         23, and except as otherwise expressly provided herein, such default
         shall continue for more than 30 days after Landlord shall have given
         Tenant written notice of such default.

         24.      LANDLORD'S REMEDIES. Upon each occurrence of an Event of
Default and so long as such Event of Default shall be continuing, Landlord may
at any time thereafter at its election: terminate this Lease or Tenant's right
of possession (but Tenant shall remain liable as hereinafter provided), and/or
pursue any other remedies at law or in equity. Upon the termination of this
Lease or termination of Tenant's right of possession, it shall be lawful for
Landlord, without formal demand or notice of any kind, to re-enter the Premises
by summary dispossession proceedings or any other action or proceeding
authorized by law and to remove Tenant and all persons and property therefrom.
If Landlord re-enters the Premises, Landlord shall have the right to keep in
place and use, or remove and store, all of the furniture, fixtures and equipment
at the Premises.

                  Except as otherwise provided in the next paragraph, if Tenant
breaches this Lease and abandons the Premises prior to the end of the term
hereof, or if Tenant's right to possession is terminated by Landlord because of
an Event of Default by Tenant under this Lease, this Lease shall terminate. Upon
such termination, Landlord may recover from Tenant the following, as provided in
Section 1951.2 of the Civil Code of California: (i) the worth at the time of
award of the unpaid Base Rent and other charges under this Lease that had been
earned at the time of termination; (ii) the worth at the time of award of the
amount by which the reasonable value of the unpaid Base Rent and other charges
under this Lease which would have been earned after termination until the time
of award exceeds the amount of such rental loss that Tenant proves could have
been reasonably avoided; (iii) the worth at the time of award by which the
reasonable value of the unpaid Base Rent and other charges under this Lease for
the balance of the term of this Lease after the time of award exceeds the amount
of such rental loss that Tenant proves could have been reasonably avoided; and
(iv) any other amount necessary to compensate Landlord for all the detriment
proximately caused by Tenant's failure to perform its obligations under this
Lease or that in the ordinary course of things would be likely to result
therefrom. As used herein, the following terms are defined: (a) The "worth at
the

                                      -7-
<PAGE>

time of award" of the amounts referred to in Sections (i) and (ii) is computed
by allowing interest at the lesser of 18 percent per annum or the maximum lawful
rate. The "worth at the time of award" of the amount referred to in Section
(iii) is computed by discounting such amount at the discount rate of the Federal
Reserve Bank of San Francisco at the time of award plus one percent; (b) The
"time of award" as used in clauses (i), (ii), and (iii) above is the date on
which judgment is entered by a court of competent jurisdiction; (c) The
"reasonable value" of the amount referred to in clause (ii) above is computed by
determining the mathematical product of (1) the "reasonable annual rental value"
(as defined herein) and (2) the number of years, including fractional parts
thereof, between the date of termination and the time of award. The "reasonable
value" of the amount referred to in clause (iii) is computed by determining the
mathematical product of (1) the annual Base Rent and other charges under this
Lease and (2) the number of years including fractional parts thereof remaining
in the balance of the term of this Lease after the time of award.

                  Even though Tenant has breached this Lease and abandoned the
Premises, this Lease shall continue in effect for so long as Landlord does not
terminate Tenant's right to possession, and Landlord may enforce all its rights
and remedies under this Lease, including the right to recover rent as it becomes
due. This remedy is intended to be the remedy described in California Civil Code
Section 1951.4, and the following provision from such Civil Code Section is
hereby repeated: "The Lessor has the remedy described in California Civil Code
Section 1951.4 (lessor may continue lease in effect after lessee's breach and
abandonment and recover rent as it becomes due, if lessee has right to sublet or
assign, subject only to reasonable limitations)." Any such payments due Landlord
shall be made upon demand therefor from time to time and Tenant agrees that
Landlord may file suit to recover any sums falling due from time to time.
Notwithstanding any such reletting without termination, Landlord may at any time
thereafter elect in writing to terminate this Lease for such previous breach.

                  Exercise by Landlord of any one or more remedies hereunder
granted or otherwise available shall not be deemed to be an acceptance of
surrender of the Premises and/or a termination of this Lease by Landlord,
whether by agreement or by operation of law, it being understood that such
surrender and/or termination can be effected only by the written agreement of
Landlord and Tenant. Any law, usage, or custom to the contrary notwithstanding,
Landlord shall have the right at all times to enforce the provisions of this
Lease in strict accordance with the terms hereof; and the failure of Landlord at
any time to enforce its rights under this Lease strictly in accordance with same
shall not be construed as having created a custom in any way or manner contrary
to the specific terms, provisions, and covenants of this Lease or as having
modified the same. Tenant and Landlord further agree that forbearance or waiver
by Landlord to enforce its rights pursuant to this Lease or at law or in equity,
shall not be a waiver of Landlord's right to enforce one or more of its rights
in connection with any subsequent default. A receipt by Landlord of rent or
other payment with knowledge of the breach of any covenant hereof shall not be
deemed a waiver of such breach, and no waiver by Landlord of any provision of
this Lease shall be deemed to have been made unless expressed in writing and
signed by Landlord. To the greatest extent permitted by law, Tenant waives the
service of notice of Landlord's intention to re-enter as provided for in any
statute, or to institute legal proceedings to that end, and also waives all
right of redemption in case Tenant shall be dispossessed by a judgment or by
warrant of any court or judge. The terms "enter," "re-enter," "entry" or
"re-entry," as used in this Lease, are not restricted to their technical legal
meanings. Any reletting of the Premises shall be on such terms and conditions as
Landlord in its sole discretion may determine (including without limitation a
term different than the remaining Lease Term, rental concessions, alterations
and repair of the Premises, lease of less than the entire Premises to any tenant
and leasing any or all other portions of the Project before reletting the
Premises). Landlord shall not be liable, nor shall Tenant's obligations
hereunder be diminished, because of Landlord's failure to relet the Premises or
collect rent due in respect of such reletting.

         25       TENANT'S REMEDIES/LIMITATION OF LIABILITY. Landlord shall not
be in default hereunder unless Landlord fails to perform any of its obligations
hereunder within 30 days after written notice from Tenant specifying such
failure (unless such performance will, due to the nature of the obligation,
require a period of time in excess of 30 days, then after such period of time as
is reasonably necessary). All obligations of Landlord hereunder shall be
construed as covenants, not conditions; and, except as may be otherwise
expressly provided in this Lease, Tenant may not terminate this Lease for breach
of Landlord's obligations hereunder. All obligations of Landlord under this
Lease will be binding upon Landlord only during the period of its ownership of
the Premises and not thereafter. The term "Landlord" in this Lease shall mean
only the owner, for the time being of the Premises, and in the event of the
transfer by such owner of its interest in the Premises, such owner shall
thereupon be released and discharged from all obligations of Landlord thereafter
accruing, but such obligations shall be binding during the Lease Term upon each
new owner for the duration of such owner's ownership. Any liability of Landlord
under this Lease shall be limited solely to its interest in the Project, and in
no event shall any personal liability be asserted against Landlord in connection
with this Lease nor shall any recourse be had to any other property or assets of
Landlord.

         26       WAIVER OF JURY TRIAL. TENANT AND LANDLORD WAIVE ANY RIGHT TO
TRIAL BY JURY OR TO HAVE A JURY PARTICIPATE IN RESOLVING ANY DISPUTE, WHETHER
SOUNDING IN CONTRACT, TORT, OR OTHERWISE, BETWEEN LANDLORD AND TENANT ARISING
OUT OF THIS LEASE OR ANY OTHER INSTRUMENT, DOCUMENT, OR AGREEMENT EXECUTED OR
DELIVERED IN CONNECTION HEREWITH OR THE TRANSACTIONS RELATED HERETO.

         27       SUBORDINATION. This Lease and Tenant's interest and rights
hereunder are and shall be subject and subordinate at all times to the lien of
any first mortgage, now existing or hereafter created on or against the Project
or the Premises, and all amendments, restatements, renewals, modifications,
consolidations, refinancing, assignments and extensions thereof, without the
necessity of any further instrument or act on the part of Tenant. Tenant agrees,
at

                                      -8-
<PAGE>

the election of the holder of any such mortgage, to attorn to any such holder.
Tenant agrees upon demand to execute, acknowledge and deliver such instruments,
confirming such subordination and such instruments of attornment as shall be
requested by any such holder. Notwithstanding the foregoing, any such holder may
at any time subordinate its mortgage to this Lease, without Tenant's consent, by
notice in writing to Tenant, and thereupon this Lease shall be deemed prior to
such mortgage without regard to their respective dates of execution, delivery or
recording and in that event such holder shall have the same rights with respect
to this Lease as though this Lease had been executed prior to the execution,
delivery and recording of such mortgage and had been assigned to such holder.
The term "mortgage" whenever used in this Lease shall be deemed to include deeds
of trust, security assignments and any other encumbrances, and any reference to
the "holder" of a mortgage shall be deemed to include the beneficiary under a
deed of trust.

         28       MECHANIC'S LIENS. Tenant has no express or implied authority
to create or place any lien or encumbrance of any kind upon, or in any manner to
bind the interest of Landlord or Tenant in, the Premises or to charge the
rentals payable hereunder for any claim in favor of any person dealing with
Tenant, including those who may furnish materials or perform labor for any
construction or repairs. Tenant covenants and agrees that it will pay or cause
to be paid all sums legally due and payable by it on account of any labor
performed or materials furnished in connection with any work performed on the
Premises and that it will save and hold Landlord harmless from all loss, cost or
expense based on or arising out of asserted claims or liens against the
leasehold estate or against the interest of Landlord in the Premises or under
this Lease. Tenant shall give Landlord immediate written notice of the placing
of any lien or encumbrance against the Premises and cause such lien or
encumbrance to be discharged within 30 days of the filing or recording thereof;
provided, however, Tenant may contest such liens or encumbrances as long as such
contest prevents foreclosure of the lien or encumbrance and Tenant causes such
lien or encumbrance to be bonded or insured over in a manner satisfactory to
Landlord within such 30 day period.

         29       ESTOPPEL CERTIFICATES. Tenant agrees, from time to time,
within 10 days after request of Landlord, to execute and deliver to Landlord, or
Landlord's designee, any estoppel certificate requested by Landlord, stating
that this Lease is in full force and effect, the date to which rent has been
paid, that Landlord is not in default hereunder (or specifying in detail the
nature of Landlord's default), the termination date of this Lease and such other
matters pertaining to this Lease as may be requested by Landlord. Tenant's
obligation to furnish each estoppel certificate in a timely fashion is a
material inducement for Landlord's execution of this Lease. No cure or grace
period provided in this Lease shall apply to Tenant's obligations to timely
deliver an estoppel certificate.

         30       ENVIRONMENTAL REQUIREMENTS. Except for Hazardous Material
contained in products used by Tenant in de minimis quantities for ordinary
cleaning and office purposes and those provided for in Addendum V, Tenant shall
not permit or cause any party to bring any Hazardous Material upon the Premises
or transport, store, use, generate, manufacture or release any Hazardous
Material in or about the Premises without Landlord's prior written consent.
Tenant, at its sole cost and expense, shall operate its business in the Premises
in strict compliance with all Environmental Requirements and shall remediate in
manner satisfactory to Landlord any Hazardous Materials released on or from the
Project by Tenant, its agents, employees, contractors, subtenants or invitees.
Tenant shall complete and certify to disclosure statements as requested by
Landlord from time to time relating to Tenant's transportation, storage, use,
generation, manufacture, or release of Hazardous Materials on the Premises. The
term "Environmental Requirements" means all applicable present and future
statutes, regulations, ordinances, rules, codes, judgments, orders or other
similar enactments of any governmental authority or agency regulating or
relating to health, safety, or environmental conditions on, under, or about the
Premises or the environment, including without limitation, the following: the
Comprehensive Environmental Response, Compensation and Liability Act; the
Resource Conservation and Recovery Act; and all state and local counterparts
thereto, and any regulations or policies promulgated or issued thereunder. The
term "Hazardous Materials" means and includes any substance, material, waste,
pollutant, or contaminant listed or defined as hazardous or toxic, under any
Environmental Requirements, asbestos and petroleum, including crude oil or any
fraction thereof, natural gas, or synthetic gas usable for fuel (or mixtures of
natural gas and such synthetic gas). As defined in Environmental Requirements,
Tenant is and shall be deemed to be the "operator" of Tenant's "facility" and
the "owner" of all Hazardous Materials brought on the Premises by Tenant, its
agents, employees, contractors or invitees, and the wastes, by-products, or
residues generated, resulting, or produced therefrom.

                  Tenant shall indemnify, defend, and hold Landlord harmless
from and against any and all losses (including, without limitation, diminution
in value of the Premises or the Project and loss of rental income from the
Project), claims, demands, actions, suits, damages (including, without
limitation, punitive damages), expenses (including, without limitation,
remediation, removal, repair, corrective action, or cleanup expenses), and costs
(including, without limitation, actual attorneys' fees, consultant fees or
expert fees and including, without limitation, removal or management of any
asbestos brought into the Premises or disturbed in breach of the requirements of
this Paragraph 30, regardless of whether such removal or management is required
by law) which are brought or recoverable against, or suffered or incurred by
Landlord as a result of any release of Hazardous Materials for which Tenant is
obligated to remediate as provided above or any other breach of the requirements
under this Paragraph 30 by Tenant, its agents, employees, contractors,
subtenants, assignees or invitees, regardless of whether Tenant had

                                      -9-
<PAGE>

knowledge of such noncompliance. The obligations of Tenant under this Paragraph
30 shall survive any termination of this Lease.

                  Landlord shall have access to, and a right to perform
inspections and tests of, the Premises to determine Tenant's compliance with
Environmental Requirements, its obligations under this Paragraph 30, or the
environmental condition of the Premises. Access shall be granted to Landlord
upon Landlord's prior notice to Tenant and at such times so as to minimize, so
far as may be reasonable under the circumstances, any disturbance to Tenant's
operations. Such inspections and tests shall be conducted at Landlord's expense,
unless such inspections or tests reveal that Tenant has not complied with any
Environmental Requirement, in which case Tenant shall reimburse Landlord for the
reasonable cost of such inspection and tests. Landlord's receipt of or
satisfaction with any environmental assessment in no way waives any rights that
Landlord holds against Tenant.

         31       RULES AND REGULATIONS. Tenant shall, at all times during the
Lease Term and any extension thereof, comply with all reasonable rules and
regulations at any time or from time to time established by Landlord covering
use of the Premises and the Project. The current rules and regulations are
attached hereto. In the event of any conflict between said rules and regulations
and other provisions of this Lease, the other terms and provisions of this Lease
shall control. Landlord shall not have any liability or obligation for the
breach of any rules or regulations by other tenants in the Project.

         32       SECURITY SERVICE. Tenant acknowledges and agrees that, while
Landlord may patrol the Project, Landlord is not providing any security services
with respect to the Premises and that Landlord shall not be liable to Tenant
for, and Tenant waives any claim against Landlord with respect to, any loss by
theft or any other damage suffered or incurred by Tenant in connection with any
unauthorized entry into the Premises or any other breach of security with
respect to the Premises.

         33       FORCE MAJEURE. Landlord shall not be held responsible for
delays in the performance of its obligations hereunder when caused by strikes,
lockouts, labor disputes, acts of God, inability to obtain labor or materials or
reasonable substitutes therefor, governmental restrictions, governmental
regulations, governmental controls, delay in issuance of permits, enemy or
hostile governmental action, civil commotion, fire or other casualty, and other
causes beyond the reasonable control of Landlord ("Force Majeure").

         34       ENTIRE AGREEMENT. This Lease constitutes the complete
agreement of Landlord and Tenant with respect to the subject matter hereof. No
representations, inducements, promises or agreements, oral or written, have been
made by Landlord or Tenant, or anyone acting on behalf of Landlord or Tenant,
which are not contained herein, and any prior agreements, promises,
negotiations, or representations are superseded by this Lease. This Lease may
not be amended except by an instrument in writing signed by both parties hereto.

         35       SEVERABILITY. If any clause or provision of this Lease is
illegal, invalid or unenforceable under present or future laws, then and in that
event, it is the intention of the parties hereto that the remainder of this
Lease shall not be affected thereby. It is also the intention of the parties to
this Lease that in lieu of each clause or provision of this Lease that is
illegal, invalid or unenforceable, there be added, as a part of this Lease, a
clause or provision as similar in terms to such illegal, invalid or
unenforceable clause or provision as may be possible and be legal, valid and
enforceable.

         36       BROKERS. Tenant represents and warrants that it has dealt with
no broker, agent or other person in connection with this transaction and that no
broker, agent or other person brought about this transaction, other than the
broker, if any, set forth on the first page of this Lease, and Tenant agrees to
indemnify and hold Landlord harmless from and against any claims by any other
broker, agent or other person claiming a commission or other form of
compensation by virtue of having dealt with Tenant with regard to this leasing
transaction.

         37       MISCELLANEOUS. (a) Any payments or charges due from Tenant to
Landlord hereunder shall be considered rent for all purposes of this Lease.

         (b)      If and when included within the term "Tenant," as used in this
instrument, there is more than one person, firm or corporation, each shall be
jointly and severally liable for the obligations of Tenant.

         (c)      All notices required or permitted to be given under this Lease
shall be in writing and shall be sent by registered or certified mail, return
receipt requested, or by a reputable national overnight courier service, postage
prepaid, or by hand delivery addressed to the parties at their addresses below,
and with a copy sent to Landlord at 14100 East 35th Place, Aurora, Colorado
80011. Either party may by notice given aforesaid change its address for all
subsequent notices. Except where otherwise expressly provided to the contrary,
notice shall be deemed given upon delivery.

         (d)      Except as otherwise expressly provided in this Lease or as
otherwise required by law, Landlord retains the absolute right to withhold any
consent or approval.

         (e)      At Landlord's request from time to time Tenant shall furnish
Landlord with true and complete copies of its most recent annual and quarterly
financial statements prepared by Tenant or Tenant's accountants and any other
financial information or summaries that Tenant typically provides to its lenders
or shareholders.

                                      -10-
<PAGE>

         (f)      Neither this Lease nor a memorandum of lease shall be filed by
or on behalf of Tenant in any public record. Landlord may prepare and file, and
upon request by Landlord Tenant will execute, a memorandum of lease.

         (g)      The normal rule of construction to the effect that any
ambiguities are to be resolved against the drafting party shall not be employed
in the interpretation of this Lease or any exhibits or amendments hereto.

         (h)      The submission by Landlord to Tenant of this Lease shall have
no binding force or effect, shall not constitute an option for the leasing of
the Premises, nor confer any right or impose any obligations upon either party
until execution of this Lease by both parties.

         (i)      Words of any gender used in this Lease shall be held and
construed to include any other gender, and words in the singular number shall be
held to include the plural, unless the context otherwise requires. The captions
inserted in this Lease are for convenience only and in no way define, limit or
otherwise describe the scope or intent of this Lease, or any provision hereof,
or in any way affect the interpretation of this Lease.

         (j)      Any amount not paid by Tenant within 5 days after its due date
in accordance with the terms of this Lease shall bear interest from such due
date until paid in full at the lesser of the highest rate permitted by
applicable law or 15 percent per year. It is expressly the intent of Landlord
and Tenant at all times to comply with applicable law governing the maximum rate
or amount of any interest payable on or in connection with this Lease. If
applicable law is ever judicially interpreted so as to render usurious any
interest called for under this Lease, or contracted for, charged, taken ,
reserved, or received with respect to this Lease, then it is Landlord's and
Tenant's express intent that all excess amounts theretofore collected by
Landlord be credited on the applicable obligation (or, if the obligation has
been or would thereby be paid in full, refunded to Tenant), and the provisions
of this Lease immediately shall be deemed reformed and the amounts thereafter
collectible hereunder reduced, without the necessity of the execution of any new
document, so as to comply with the applicable law, but so as to permit the
recovery of the fullest amount otherwise called for hereunder.

         (k)      Construction and interpretation of this Lease shall be
governed by the laws of the state in which the Project is located, excluding any
principles of conflicts of laws.

         (l)      Time is of the essence as to the performance of Tenant's
obligations under this Lease.

         (m)      All exhibits and addenda attached hereto are hereby
incorporated into this Lease and made a part hereof. In the event of any
conflict between such exhibits or addenda and the terms of this Lease, such
exhibits or addenda shall control.

         38       LIMITATION OF LIABILITY OF TRUSTEES, SHAREHOLDERS, AND
OFFICERS OF PROLOGIS TRUST. Any obligation or liability whatsoever of ProLogis
Trust, a Maryland real estate investment trust, which may arise at any time
under this Lease or any obligation or liability which may be incurred by it
pursuant to any other instrument, transaction, or undertaking contemplated
hereby shall not be personally binding upon, nor shall resort for the
enforcement thereof be had to the property of, its trustees, directors,
shareholders, officers, employees or agents, regardless of whether such
obligation or liability is in the nature of contract, tort, or otherwise.

         IN WITNESS WHEREOF, Landlord and Tenant have executed this Lease as of
the day and year first above written.

TENANT:                                           LANDLORD:

Volterra Semiconductor Corporation,     ProLogis Limited  Partnership-I,
a Delaware Corporation                  a Delaware limited partnership

                                        By: ProLogis Trust, a Maryland real
                                        estate investment trust, General Partner

By:   /s/ Greg Hildebrand
       ----------------------
Name:     Greg Hildebrand
Title:    Director of Finance           By: /s/ Ned K. Anderson
                                            -------------------
                                                Ned K. Anderson

                                      -11-
<PAGE>

                                        Title:  Managing Director

Address:                                Address:

42840 Christy Street, Suite 202         47775 Fremont Boulevard
Fremont, CA  94538                      Fremont, CA 94538

                                      -12-
<PAGE>


                              Rules and Regulations

1.       The sidewalk, entries, and driveways of the Project shall not be
         obstructed by Tenant, or its agents, or used by them for any purpose
         other than ingress and egress to and from the Premises.

2.       Tenant shall not place any objects, including antennas, outdoor
         furniture, etc., in the parking areas, landscaped areas or other areas
         outside of its Premises, or on the roof of the Project.

3.       Except for seeing-eye dogs, no animals shall be allowed in the offices,
         halls, or corridors in the Project.

4.       Tenant shall not disturb the occupants of the Project or adjoining
         buildings by the use of any radio or musical instrument or by the
         making of loud or improper noises.

5.       If Tenant desires telegraphic, telephonic or other electric connections
         in the Premises, Landlord or its agent will direct the electrician as
         to where and how the wires may be introduced; and, without such
         direction, no boring or cutting of wires will be permitted. Any such
         installation or connection shall be made at Tenant's expense.

6.       Tenant shall not install or operate any steam or gas engine or boiler,
         or other mechanical apparatus in the Premises, except as specifically
         approved in the Lease. The use of oil, gas or inflammable liquids for
         heating, lighting or any other purpose is expressly prohibited.
         Explosives or other articles deemed extra hazardous shall not be
         brought into the Project.

7.       Parking any type of recreational vehicles is specifically prohibited on
         or about the Project. Except for the overnight parking of operative
         vehicles, no vehicle of any type shall be stored in the parking areas
         at any time. In the event that a vehicle is disabled, it shall be
         removed within 48 hours. There shall be no "For Sale" or other
         advertising signs on or about any parked vehicle. All vehicles shall be
         parked in the designated parking areas in conformity with all signs and
         other markings. All parking will be open parking, and no reserved
         parking, numbering or lettering of individual spaces will be permitted
         except as specified by Landlord.

8.       Tenant shall maintain the Premises free from rodents, insects and other
         pests.

9.       Landlord reserves the right to exclude or expel from the Project any
         person who, in the judgment of Landlord, is intoxicated or under the
         influence of liquor or drugs or who shall in any manner do any act in
         violation of the Rules and Regulations of the Project.

10.      Tenant shall not cause any unnecessary labor by reason of Tenant's
         carelessness or indifference in the preservation of good order and
         cleanliness. Landlord shall not be responsible to Tenant for any loss
         of property on the Premises, however occurring, or for any damage done
         to the effects of Tenant by the janitors or any other employee or
         person.

11.      Tenant shall give Landlord prompt notice of any defects in the water,
         lawn sprinkler, sewage, gas pipes, electrical lights and fixtures,
         heating apparatus, or any other service equipment affecting the
         Premises.

12.      Tenant shall not permit storage outside the Premises, including without
         limitation, outside storage of trucks and other vehicles, or dumping of
         waste or refuse or permit any harmful materials to be placed in any
         drainage system or sanitary system in or about the Premises.

13.      All moveable trash receptacles provided by the trash disposal firm for
         the Premises must be kept in the trash enclosure areas, if any,
         provided for that purpose.

14.      No auction, public or private, will be permitted on the Premises or the
         Project.

15.      No awnings shall be placed over the windows in the Premises except with
         the prior written consent of Landlord.

16.      The Premises shall not be used for lodging, sleeping or cooking or for
         any immoral or illegal purposes or for any purpose other than that
         specified in the Lease. No gaming devices shall be operated in the
         Premises.

17.      Tenant shall ascertain from Landlord the maximum amount of electrical
         current which can safely be used in the Premises, taking into account
         the capacity of the electrical wiring in the Project and the Premises
         and the needs of other tenants, and shall not use more than such safe
         capacity. Landlord's consent to the installation of electric equipment
         shall not relieve Tenant from the obligation not to use more
         electricity than such safe capacity.

18.      Tenant assumes full responsibility for protecting the Premises from
         theft, robbery and pilferage.

19.      Tenant shall not install or operate on the Premises any machinery or
         mechanical devices of a nature not directly related to Tenant's
         ordinary use of the Premises and shall keep all such machinery free of
         vibration, noise and air waves which may be transmitted beyond the
         Premises.

                                      -13-
<PAGE>

                 HVAC Maintenance/Service Contract Requirements

A service contract with a Landlord approved HVAC contractor must become
effective within thirty (30) days of occupancy and service visits should be
performed on a quarterly basis. The following are the approved HVAC contractors:

                  Thermoscape                                 (510) 445-0700
                  Phoenix Heating and Air Conditioning        (408) 487-0390
                  Cal-Air Conditioning                        (408) 947-0155

We suggest that you send the following list to one of the above HVAC contractors
to be assured that these items are included in the maintenance contract:

1.       Adjust belt tension;

2.       Lubricate all moving parts, as necessary;

3.       Inspect and adjust all temperature and safety controls;

4.       Check refrigeration system for leaks and operation;

5.       Check refrigeration system for moisture;

6.       Inspect compressor oil level and crank case heaters;

7.       Check head pressure, suction pressure and oil pressure;

8.       Inspect air filters and replace when necessary;

9.       Check space conditions;

10.      Check condensate drains and drain pans and clean, if necessary;

11.      Inspect and adjust all valves;

12.      Check and adjust dampers;

13.      Run machine through complete cycle.

Note:    A certificate must be provided for our files not later than thirty (30)
         days after mutual execution hereof. Failure to provide such certificate
         or perform said services, when required, shall constitute material
         default of this lease.

                                      -14-
<PAGE>

                                   ADDENDUM II

                                  CONSTRUCTION
                                   (ALLOWANCE)

                  ATTACHED TO AND A PART OF THE LEASE AGREEMENT
               DATED _____________________________, 2000, BETWEEN

                         ProLogis Limited Partnership I
                                       and
                       Volterra Semiconductor Corporation

                  (a)      Landlord agrees to furnish or perform at Landlord's
sole cost and expense those items of construction and those improvements (the
"Tenant Improvements") as shown on Exhibit B and detailed in Exhibit B-1
specified below:

                  The Tenant Improvements shall be formally documented by a
signed floor plan, which shall be subject to Landlord's approval. The scope of
work shall include improving the Premises to 100% drop ceiling environment,
expanding the restroom core and other associated changes. The Tenant Improvement
costs shall include but not be limited to actual construction costs,
architectural and engineering fees, permit fees and city impact fees.

                  Landlord shall pay for the Tenant Improvement up to a maximum
amount of $60,000, and Tenant shall pay for the cost of the Tenant Improvements
in excess of such amount. If the cost of the Tenant Improvement is estimated to
exceed such amount, such estimated overage shall be paid by the Tenant to the
general contractor in accordance with an agreed upon payment schedule between
Tenant, Landlord and general contractor. Tenant at Landlord's sole discretion
may be required to contract directly for Tenant Improvements with Landlord's
selected contractors. Should this be the case Landlord shall be responsible for
$60,000 of the Tenant Improvement costs and Tenant shall be responsible for any
costs in excess of such amount. Landlord shall pay Tenant its portion of such
costs upon completion of the Tenant Improvements issuance of a final permit by
the City of Fremont and Landlord's receipt of final lien releases from
contractor and documentation of final payments of all outstanding bills.

                  (b)      If Tenant shall desire any changes, Tenant shall so
advise Landlord in writing and Landlord shall determine whether such changes can
be made in a reasonable and feasible manner. Any and all costs of reviewing any
requested changes, and any and all costs of making any changes to the Tenant
Improvements which Tenant may request and which Landlord may agree to shall be
at Tenant's sole cost and expense and shall be paid to Landlord upon demand and
before execution of the change order.

                  (c)      Landlord shall proceed with and complete the
construction of the Tenant Improvements. As soon as such improvements have been
Substantially Completed, Landlord shall notify Tenant in writing of the date
that the Tenant Improvements were Substantially Completed. Such date, unless an
earlier date is specified as the Commencement Date in this Lease or otherwise
agreed to in writing between Landlord and Tenant, shall be the "Commencement
Date," unless the completion of such improvements was delayed due to any act or
omission of, or delay caused by, Tenant including, without limitation, Tenant's
failure to approve plans, complete submittals or obtain permits within the time
periods agreed to by the parties or as reasonably required by Landlord, in which
case the Commencement Date shall be the date such improvements would have been
completed but for the delays caused by Tenant. The Tenant Improvements shall be
deemed substantially completed ("Substantially Completed") when, in the opinion
of the construction manager (whether an employee or agent of Landlord or a third
party construction manager), the Premises are substantially completed except for
punch list items which do not prevent in any material way the use of the
Premises for the purposes for which they were intended. After the Commencement
Date Tenant shall, upon demand, execute and deliver to Landlord a letter of
acceptance of delivery of the Premises.

                  (d)      The failure of Tenant to take possession of or to
occupy the Premises shall not serve to relieve Tenant of obligations arising on
the Commencement Date or delay the payment of rent by Tenant. Subject to
applicable ordinances and building codes governing Tenant's right to occupy or
perform in the Premises, Tenant shall be allowed to install its tenant
improvements, machinery, equipment, fixtures, or other property on the Premises
during the final stages of completion of construction provided that Tenant does
not thereby interfere with the completion of construction or cause any labor
dispute as a result of such installations, and provided further that Tenant does
hereby agree to indemnify, defend, and hold Landlord harmless from any loss or
damage to such property, and all liability, loss, or damage arising from any
injury to the Project or the property of Landlord, its contractors,
subcontractors, or materialmen, and any death or personal injury to any person
or persons arising out of such installations, whether or not any such loss,
damage, liability, death, or personal injury was caused by Landlord's
negligence. Any such occupancy or performance in the Premises shall be in
accordance with the provisions governing Tenant-Made Alterations and Trade
Fixtures in the Lease, and shall be subject to Tenant providing to Landlord
satisfactory evidence of insurance for personal injury and property damage
related to such installations and satisfactory payment arrangements with respect
to installations permitted hereunder. Delay in putting Tenant in possession of
the Premises shall not serve to extend the term of this Lease or to make
Landlord liable for any damages arising therefrom.

                  (e)      Except for incomplete punch list items, Tenant upon
the Commencement Date shall have and hold the Premises as the same shall then be
without any liability or obligation on the part of Landlord for making any
further alterations or improvements of any kind in or about the Premises.

                                      -16-
<PAGE>

                                  ADDENDUM III
                                LETTER OF CREDIT

                  ATTACHED TO AND A PART OF THE LEASE AGREEMENT
                    DATED ____________________, 2000, BETWEEN

                         ProLogis Limited Partnership-I
                                       and
                       Volterra Semiconductor Corporation

         Upon execution of the Lease, Tenant shall provide Landlord a Letter of
Credit in the amount of $366,000 which may be in the form of an unconditional,
irrevocable letter of credit from a bank reasonably acceptable to Landlord. The
primary purpose of the Letter of Credit is to reimburse Landlord for Leasing
costs including but not limited to brokerage commissions, Tenant Improvements,
and additional security in the event of default. The letter of credit shall
either provide that it does not expire until 60 days after the end of the Lease
term or, if it is for less than the full term of the Lease, shall be renewed by
Tenant at least 30 days prior to its expiration during the term of the Lease.
The letter of credit shall provide that it may be drawn down upon by Landlord at
any time Landlord delivers its site draft to the bank. If Landlord sells or
conveys the Premises, Tenant shall, at Landlord's request, cooperate in having
the letter of credit transferred to the purchaser. If the letter of credit is
ever drawn upon by Landlord pursuant to the terms of the Lease and this
Addendum, tenant shall within ten (10) days thereafter cause the letter of
credit to be restored to its original amount.

         Provided Tenant is currently not and has not been in default of the
Lease in the prior twelve month period (in excess of one (1) time which has not
been cured within five (5) business days after notice) the Letter of Credit
shall be reduced per the following schedule:

<TABLE>
<CAPTION>
          PERIOD                                       LETTER OF CREDIT AMOUNT
          -----                                        -----------------------
<S>                                                    <C>
September 1, 2000 - August 31, 2001                           $366,000.00
September 1, 2001 - August 31, 2002                           $266,000.00
September 1, 2002 - August 31, 2003                           $216,000.00
September 1, 2003 - August 31, 2004                           $191,000.00
September 1, 2004 - August 31, 2005                           $166,000.00
</TABLE>

                                      -17-
<PAGE>

                            FORM OF LETTER OF CREDIT

                      [LETTERHEAD OF LETTER OF CREDIT BANK]

                                                      [DATE]

ProLogis Trust

Attention:  _______________

         Re:      Irrevocable Transferrable Letter of Credit
                  No._______________________________________

Beneficiary:

         By order of our client, (the "Applicant"), we hereby establish this
Irrevocable Transferrable Letter of Credit No. in your favor for an amount up to
but not exceeding the aggregate sum of ___________________ and No/100 Dollars
($_________) (as reduced from time to time in accordance with the terms hereof,
the "Letter of Credit Amount"), effective immediately, and expiring on the close
of business at our office at the address set forth above one year from the date
hereof unless renewed as hereinafter provided.

         Funds under this Letter of Credit are available to you on or prior to
the expiry date against presentation by you of your (i) sight drafts drawn on us
in the form of Annex 1 hereto, indicating this Letter of Credit number and (ii)
request in the form of Annex 2 hereto (such sight draft and request, together
referred to as a "Drawing Request"), sight draft(s), completed and signed by one
of your officers. Presentation of your Drawing Requests may be made by you to us
at the address set forth above or may be made by facsimile transmission, to the
following facsimile number __________. You may present to us one or more Drawing
Requests from time to time prior to the expiry date in an aggregate amount not
to exceed the Letter of Credit Amount then in effect (it being understood that
the honoring by us of each Drawing Request shall reduce the Letter of Credit
Amount then in effect).

         This Letter of Credit will be automatically renewed for a one-year
period upon the expiration date set forth above and upon each anniversary of
such date, unless at least sixty (60) days prior to such expiration date, or
prior to any anniversary of such date, we notify both you and the Applicant in
writing by certified mail that we elect not to so renew the Letter of Credit.

         This Letter of Credit sets forth in full the terms of our undertaking
and such undertaking shall not in any way be modified, amended or amplified by
reference to any document or instrument referred to herein or in which this
Letter of Credit is referred to or to which this Letter of Credit relates, and
no such reference shall be deemed to incorporate herein by reference any
document or instrument.

         All bank charges and commissions incurred in this transaction are for
the Applicant's account.

         This Letter of Credit is transferrable by you and your successors and
assigns any number of times in its entirety and not in part, but only by
delivery to us of a Notice of Assignment in the form of Annex 3 hereto.

         We hereby agree with the drawers, endorsers, and bona fide holders of
drafts drawn under and in compliance with the terms of this Letter of Credit
that such drafts will be duly honored upon presentation to the drawee from our
own funds and not the funds of the Applicant and shall be available to such
drawers, endorsers, and bona fide holders, as the case may be, on or before
noon, New York time, on the Business Day (defined below) next following the date
on which such drafts are received by us. "Business Day" shall mean any day which
is not a Saturday, Sunday or day on which we are required or authorized by law
to be closed in New York, New York.

         To the extent not inconsistent with the express terms hereof, this
Letter of Credit shall be governed by, and construed in accordance with, the
terms of the Uniform Customs and Practice for Commercial Documentary Credits
(1993 Revision), I.C.C. Publication No. 500 (the "UCP 500") and as to matters
not governed by the UCP 500, this Letter of Credit shall be governed by and
construed in accordance with the laws of the State of New York.

                              Very truly yours,

                              [NAME OF LETTER OF CREDIT BANK]

                              By:________________________________
                                 Name:
                                 Title:

                                      -18-
<PAGE>

                                                                         ANNEX 1

                                   SIGHT DRAFT

                                                                __________, 2000

         For value received, at sight pay to the order of PROLOGIS TRUST, the
sum of [Amount in words] [Amount in Figures] United States Dollars drawn under
[Name of Letter of Credit Bank] Irrevocable Transferrable Letter of Credit No.
________ dated _________________, 2000.

                              PROLOGIS TRUST

                              By:________________________________
                                     Ned K. Anderson
                              Title: Managing Director

                                      -19-
<PAGE>

                                                                         ANNEX 2

                                 DRAWING REQUEST

                                                                __________, 2000

[NAME AND ADDRESS OF LETTER
OF CREDIT BANK]

         Re: Irrevocable Transferrable Letter of Credit No._____ (the "Letter of
Credit")

         The undersigned (the "Beneficiary"), hereby certifies to [Name of
Letter of Credit Bank] (the "Issuer") that:

         (a)      The Beneficiary is making a request for payment in lawful
currency of the United States of America under Irrevocable Transferrable Letter
of Credit No. _________ (the "Letter of Credit") in the amount of $ _________.

         (b)      The Letter of Credit Amount (as defined in the Letter of
Credit) as of the date hereof and prior to payment of the amount demanded in
this Drawing Request is $ ________. The amount requested by this Drawing
Request does not exceed the Letter of Credit Amount.

         [(c)     Demand is made for payment under the Letter of Credit as a
result of the occurrence and continuation of an Event of Default (as defined in
the Lease Agreement).]

         Please wire transfer the proceeds of the drawing to the following
account of the Beneficiary at the financial institution indicated below:

         Unless otherwise defined, all capitalized terms used herein have the
meanings provided in, or by reference in, the Letter of Credit.

         IN WITNESS WHEREOF, the undersigned has duly executed and delivered
this Drawing Request as of the ___ day of _______________, 2000.

                              PROLOGIS TRUST

                              By:____________________________
                                 Name:  Ned K. Anderson
                                 Title: Managing Director

                                      -20-
<PAGE>

                                                                         ANNEX 3

                              NOTICE OF ASSIGNMENT

                                                              ____________, 2000

[NAME AND ADDRESS OF
LETTER OF CREDIT BANK]

                  Re:  Irrevocable Transferable Letter of Credit No.

         The undersigned (the "Beneficiary"), hereby notifies [Name of Letter of
Credit Bank] (the "Issuer") that it has irrevocably assigned the
above-referenced Letter of Credit to _________ (the "Assignee") with an address
at ________________ effective as of the date the Issuer receives this Notice of
Assignment. The Assignee acknowledges and agrees that the Letter of Credit
Amount may have been reduced pursuant to the terms thereof, and that the
Assignee is bound by any such reduction.

         IN WITNESS WHEREOF, the undersigned has duly executed and delivered
this Notice of Assignment as of this _____ day of _______, 2000.

                              PROLOGIS TRUST

                              By:
                                 Ned K. Anderson
                                 Title: Managing Director

Agreed:

[Assignee]

                                      -21-
<PAGE>

                                   ADDENDUM IV

                                 RENEWAL OPTION

                  ATTACHED TO AND A PART OF THE LEASE AGREEMENT
              DATED _______________________________, 2000, BETWEEN

                         ProLogis Limited Partnership I
                                       and
                       Volterra Semiconductor Corporation

         (a)      Provided that as of the time of the giving of the Extension
Notice and the Commencement Date of the Extension Term, (x) Tenant is the Tenant
originally named herein, (y) Tenant actually occupies all of the Premises
initially demised under this Lease and any space added to the Premises, and (z)
no Event of Default exists, or would exist but for the passage of time or the
giving of notice, or both; then Tenant shall have the right to extend the Lease
Term for an additional term of five (5) years (such additional term is
hereinafter called the "Extension Term") commencing on the day following the
expiration of the Lease Term (hereinafter referred to as the "Commencement Date
of the Extension Term"). Tenant must give Landlord notice (hereinafter called
the "Extension Notice") of its election to extend the term of the Lease Term at
least five (5) months, but not more than nine (9) months, prior to the scheduled
expiration date of the Lease Term.

         (b)      The Base Rent payable by Tenant to Landlord during the
Extension Term shall be the greater of (i) the Base Rent applicable to the last
year of the initial term and (ii) the then prevailing market rate for comparable
space in the Project and comparable buildings in the vicinity of the Project,
taking into account the size of the Lease, the length of the renewal term,
market escalations and the credit of Tenant. The Base Rent shall not be reduced
by reason of any costs or expenses saved by Landlord by reason of Landlord's not
having to find a new tenant for such premises (including, without limitation,
brokerage commissions, costs of improvements, rent concessions or lost rental
income during any vacancy period). Provided Tenant and Landlord negotiate in
good faith and in the event Landlord and Tenant fail to reach an agreement on
such rental rate and execute the Amendment (defined below) at least four (4) (3)
months prior to the expiration of the Lease, then Tenant's exercise of the
renewal option shall be deemed withdrawn and the Lease shall terminate on its
original expiration date.

         (c)      The determination of the Base Rent does not reduce the
Tenant's obligation to pay or reimburse Landlord for Operating Expenses and
other reimbursable items as set forth in the Lease, and Tenant shall reimburse
and pay Landlord as set forth in the Lease with respect to such Operating
Expenses and other items with respect to the Premises during the Extension Term
without regard to any cap on such expenses set forth in the Lease.

         (d)      Except for the Base Rent as determined above, Tenant's
occupancy of the Premises during the Extension Term shall be on the same terms
and conditions as are in effect immediately prior to the expiration of the
initial Lease Term; provided, however, Tenant shall have no further right to any
allowances, credits or abatements or options to expand, contract, renew or
extend the Lease.

         (e)      If Tenant does not give the Extension Notice within the period
set forth in Paragraph (a), Tenant's right to extend the Lease Term shall
automatically terminate. Time is of the essence as to the giving of the
Extension Notice.

         (f)      Landlord shall have no obligation to refurbish or otherwise
improve the Premises for the Extension Term. The Premises shall be tendered on
the Commencement Date of the Extension Term in "as-is" condition.

         (g)      If the Lease is extended for the Extension Term, then Landlord
shall prepare and Tenant shall execute an amendment to the Lease confirming the
extension of the Lease Term and the other provisions applicable thereto (the
"Amendment").

         (h)      If Tenant exercises its right to extend the term of the Lease
for the Extension Term pursuant to this Addendum, the term "Lease Term" as used
in the Lease, shall be construed to include, when practicable, the Extension
Term except as provided in (d) above.

                                      -22-
<PAGE>

                                   ADDENDUM V

                STORAGE AND USE OF PERMITTED HAZARDOUS MATERIALS

                  ATTACHED TO AND A PART OF THE LEASE AGREEMENT
                   DATED ______________________, 2000, BETWEEN

                         ProLogis Limited Partnership I
                                       and
                       Volterra Semiconductor Corporation

1.       Permitted Hazardous Materials and Use.

         (a)      Tenant has requested Landlord's consent to use the Hazardous
Materials listed below in its business at the Premises (the "Permitted Hazardous
Materials"). Subject to the conditions set forth herein, Landlord hereby
consents to the Use (hereinafter defined) of the Permitted Hazardous Materials.
Any Permitted Hazardous Materials on the Premises will be generated, used,
received, maintained, treated, stored, or disposed in a manner consistent with
good engineering practice and in compliance with all Environmental Requirements.

                  Permitted Hazardous Materials (including maximum quantities):

                  The storage, uses or processes involving the Permitted
Hazardous Materials (the "Use") are described below.

                  Use [If limited to receiving and storage, so specify]:

2.       No Current Investigation.

         Tenant represents and warrants that it is not currently subject to an
inquiry, regulatory investigation, enforcement order, or any other proceeding
regarding the generation, use, treatment, storage, or disposal of a Hazardous
Material.

3.       Notice and Reporting.

         Tenant immediately shall notify Landlord in writing of any spill,
release, discharge, or disposal of any Hazardous Material in, on or under the
Premises or the Project. All reporting obligations imposed by Environmental
Requirements are strictly the responsibility of Tenant.

         Tenant shall supply to Landlord within 5 business days after Tenant
first receives or sends the same, copies of all claims, reports, complaints,
notices, warnings or asserted violations relating in any way to Tenant's use of
the Premises.

4.       Indemnification.

         Tenant's indemnity obligation under the Lease with respect to Hazardous
Materials shall include indemnification for the liabilities, expenses and other
losses described therein as a result of the Use of the Hazardous Materials or
the breach of Tenant's obligations or representations set forth above. It is the
intent of this provision that Tenant be strictly liable to Landlord as a result
of the Use of Hazardous Materials without regard to the fault or negligence of
Tenant, Landlord or any third party.

5.       Disposal Upon Lease Termination.

          At the expiration or earlier termination of the Lease, Tenant, at its
sole cost and expense, shall: (i) remove and dispose off-site any drums,
containers, receptacles, structures, or tanks storing or containing Hazardous
Materials (or which have stored or contained Hazardous Materials) and the
contents thereof; (ii) remove, empty, and purge all underground and above ground
storage tank systems, including connected piping, of all vapors, liquids,
sludges and residues; and (iii) restore the Premises to its original condition.
Such activities shall be performed in compliance with all Environmental
Requirements and to the satisfaction of Landlord. Landlord's satisfaction with
such activities or the condition of the Premises does not waive, or release
Tenant from, any obligations hereunder.

                                      -23-
<PAGE>

                                   ADDENDUM VI

                              VACATION OF PREMISES

                  ATTACHED TO AND A PART OF THE LEASE AGREEMENT
                 DATED __________________________, 2000, BETWEEN

                         ProLogis Limited Partnership I
                                       and
                       Volterra Semiconductor Corporation

         Tenant's vacating of the Premises shall not constitute an Event of
Default if, prior to vacating the Premises, Tenant has made arrangements
reasonably acceptable to Landlord to (a) insure that Tenant's insurance for the
Premises will not be voided or cancelled with respect to the Premises as a
result of such vacancy, (b) insure that the Premises are secured and not subject
to vandalism, and (c) insure that the Premises will be properly maintained after
such vacation. Tenant shall inspect the Premises at least once each month and
report monthly in writing to Landlord on the condition of the Premises.

                                      -24-
<PAGE>

                                    EXHIBIT A

                                 Spinnaker One
                       3839 Spinnaker Court - Fremont, CA
                                 20,000 Sq Ft.

                                    SITE MAP


<PAGE>
                                   EXHIBIT B

                                 Spinnaker One
                       3839 Spinnaker Court - Fremont, CA
                                 20,000 Sq Ft.


                                (To Be Attached)


<PAGE>

                                   EXHIBIT B-1

                              WORK LETTER AGREEMENT

Construction of Initial Tenant Improvements

         I.       Definitions.

                  (a)      The term "Initial Tenant Improvements" shall mean
those improvements that Landlord is obligated to construct at its sole cost and
expense except as specified in paragraph IV below in the Premises pursuant to
plans and specifications developed therefore in accordance with Paragraph II
below.

                  (b)      The term "Tenant Improvement Costs" shall mean all
sums (i) paid to contractors, subcontractors, suppliers, and materialmen for
labor and materials furnished in connection with construction of the Initial
Tenant Improvements; (ii) paid to governmental authorities or agencies for all
necessary governmental permits, licenses, inspections and approvals related to
the Initial Tenant Improvements; (iii) engineering and architectural fees for
services required in connection with the design and construction of the Initial
Tenant Improvements. In no event shall the Tenant Improvement Costs include any
costs of procuring, constructing or installing Tenant's personal property in the
Premises.

         II.      Plans and Specifications. Landlord and Tenant shall prepare
plans and specifications including fully detailed working drawings (the "Plans
and Specifications") for the Initial Tenant Improvements that Tenant desires
Landlord to construct for Tenant's use in the Building. The Plans and
Specifications must be acceptable to both Landlord and Tenant. The Plans and
Specifications shall be consistent with and include those items shown on the
space plan attached hereto as Exhibit I and the tenant improvement standards as
outlined herein. Tenant shall cooperate diligently with the Landlord's architect
(the "Architect") and shall furnish all information required by the Architect
for completion of the Plans and Specifications. Landlord and Tenant shall
indicate their approval of the Plans and Specifications (the "Approved Plans")
by initialling them and attaching them hereto as Exhibit B.

         III.     Initial Tenant Improvement Standards.

                  (a)      Office Area

1.       CABINETS: Coffee bar and/or lunch room base cabinet(s) shall be 6'0"
         long plastic laminate with chrome wire pulls.

2.       COUNTERTOPS: The coffee bar top shall have a square front edge with a
         4" splash in plastic laminate.

3.       LAVATORY COUNTERTOPS: In multiple accommodation toilet rooms with
         multiple lavatories, the lavatories shall be installed in a plastic
         laminated countertop with a bullnosed front edge and a 4" backsplash.
         Smaller tenant spaces shall receive wall mounted lavatories.

4.       ROOF INSULATION: The insulation above conditioned office area ceilings
         shall be minimum R-11 fiberglass batts

5.       THERMAL WALL INSULATION: Walls between conditioned and unconditioned
         spaces shall receive minimum R-11 unfaced fiberglass batt insulation.

6.       ACOUSTIC INSULATION: All toilet room walls and ceilings shall receive 3
         1/2" unfaced fiberglass batt acoustic insulation.

7.       DOORS AND FRAMES: 3'-0" x 7-0' x 1-3/4", solid core, birch, B-3 stain
         prefinished with anodized aluminum frames or prefinished black (Timely)
         steel frames.

8.       INTERIOR DOOR HARDWARE: Schlage "AL" series Saturn in a brushed chrome
         626 finish.

9.       INTERIOR WINDOWS: None

10.      MIRRORS: toilet rooms shall have mirrors the length of the lavatory top
         or 24 x 36 if the lavatory is wall hung.

11.      DRYWALL PARTITIONS: office walls shall be undergrid 3-5/8" x 25 Ga.
         metal studs at 24" o.c. with 5/8" gypsum board.

12.      DRYWALL FINISH: All drywall and exposed concrete walls within the
         office and toilet rooms shall receive a skip trowel textured or smooth
         finish.

13.      WAINSCOT: Toilet room wet walls shall have 4'-6" high white Pionite
         wainscot.

14.      ACOUSTIC CEILING TILE: Office areas shall have an exposed grid acoustic
         ceiling with 24" x 48" non-directional fissured tile, installed at
         9'-0"

15.      OFFICE CARPET: Designweave or Shaw direct glue-down, 26 oz. face weight
         level loop or 30 oz cut-pile carpet without pad.

16.      LUNCH ROOM: shall have vinyl composition tile (VCT) flooring 1/8"
         gauge, standard grade, as manufactured by Tarkett or Armstrong.

17.      RUBBER BASE: The office areas shall have a 4" high topset rubber base
         as manufactured by Burke, Roppe, or Tarkett, installed in all areas
         receiving floor covering except the toilet rooms.

18.      TOILET ROOM: The flooring shall be sheet vinyl by Armstrong "Suffield",
         "Best of Both Worlds" or "Seagate" with a 6" coved base.

19.      PAINT: One (1) coat of paint in a standard light color interior flat
         latex, except in the toilet rooms and at the coffee bar which shall
         receive one (1) coat of latex semi-gloss enamel over one (1) coat of
         PVA sealer. If the walls are smooth finished, they shall receive two
         (2) coats of paint.


                                      -24-
<PAGE>

20.      TOILET ACCESSORIES: Napkin Disposals: Bobrick B-270 sanitary napkin
         disposals in each women'stoilet stall.

         Paper Towel Dispenser: Bobrick B-369 (for single accommodation toilet
         rooms) or a Bobrick B-3944 (for multiple accommodation toilet rooms)
         recessed paper towel dispenser with a waste receptacle.

         Seat Cover Dispenser: Bobrick B-221 seat cover dispenser in each toilet
         stall.

         Toilet Paper Holder: Bobrick B-686 double toilet paper holder.

         Grab Bars: Bobrick No. B6806-36 and B6806-42 stainless steel handicap
         grab bars per code.

21.      TOILET PARTITIONS: Metal, floor mounted, overhead braced toilet
         partitions with a backed enamel finish by Global Steel, Knickerbocker
         or equal in manufactures standard color.

22.      BLINDS: All exterior windows, except storefront doors, shall receive
         mini-blinds by Bali, "inside mount", in a light building standard color
         with a valance.

23.      PLUMBING FIXTURES AND TRIM: Lavatory for vanity: American Standard or
         equal, "Oval Horizon", model 3303.013, white, self-rimming with a Delta
         Model 523 WF HDF single lever type faucet assembly with a grid strainer
         and bright chrome finish. Wall-hung lavatory: American Standard or
         equal, "Lucerne", model 0355.012, white, wall mounted lavatory with a
         Delta Model 523 WF HDF single lever type faucet assembly with a grid
         strainer and bright chrome finish. Water closet: American Standard or
         equal, "Cadet Aquameter", elongated, 1.5 GPF, model 3042.12, white,
         with an Olsonite #95 seat and a Sloan #111 flush valve. Urinal:
         American Standard or equal, "Allbrook", model 6540.017, white, with a
         Sloan 180-1.5 flush valve. Coffee bar sink: Elkay or equal, "Peacemaker
         Starlite", model PSR-1918, stainless steel, with a Delta #100 faucet.

         Water heater: Sized to meet demand installed in a smitty pan draining
         into a hub drain with a trap primer.

24.      Fire sprinkler heads shall be chrome with white escutcheons,
         semirecessed, not centered, on the ceiling tiles.

25.      The HVAC system shall maintain 75 degrees indoors, on a 100 degree
         outdoor day

26.      The HVAC system shall be connected to a 7-day skip-a-day time clock and
         include a bypass timer at each thermostat.

27.      All thermostats shall have an automatic change-over feature and a
         locking cover.

28.      Toilet rooms shall have an exhaust fan.

29.      All conditioned areas shall have a supply register and a ducted return
         register. Supply and return air registers shall be white baked enamel
         2'x2' with a perforated face, flush mounted. Supply air registers shall
         have a 4-way blow.

30.      Office lighting: shall be 2'x4' three lamp lay-in fluorescent light
         fixtures with standard acrylic lens and T-12 low watt type lamps, 75
         foot candles at 3' A.F.F. or as permitted by code but no less than two
         (2) fixtures per office.

31.      Furnish and install two (2) 110V duplex receptacles in each office.

32.      Furnish and install a dedicated 110 volt fourplex outlet at the
         telephone board and two dedicated 110V outlets at the coffee bar.

33.      Furnish and install a 2" diameter P.V.C. or steel (where required by
         code)conduit for phone system from the building telephone service
         entrance to a telephone board within the tenant space.

                  (b)      Warehouse Area

1.       FULL HEIGHT DRYWALL PARTITIONS @ tenant demising walls: Metal studs
         with one layer of 5/8" type "X" gypsum board on each side from the
         floor to the roof deck.

2.       OFFICE/WAREHOUSE WALL: Metal studs with two layers of 5/8" type "X"
         gypsum board on each side to 6" A.F.F.

3.       WAREHOUSE WALL FINISH: All drywall shall be fire taped only. Spot nails
         in firetaped areas.

4.       CONCRETE FLOOR SEALER: Exposed concrete floors shall receive one coat
         of acrylic concrete sealer.

5.       WAREHOUSE LIGHTING: Provide 16' high output fluorescent strip light
         fixtures or metal halide fixtures to achieve 15 foot candles of light
         measured at 30" above the floor in the warehouse space.

(c)      Exclusions.

         The initial tenant improvement standards do not include the following
items:

1.       Electrical data gathering lines or security equipment.

2.       Telephonic or other communications equipment and cabling.

3.       Electrical connections and distribution for production equipment.

         IV.      Changes to Plans for Initial Tenant Improvements. Once the
Approved Plans have been finally approved by Tenant as provided above,
thereafter neither party shall have the right to order extra work or change
orders with respect to the construction of the Initial Tenant Improvements
without the prior written consent of the other, which consent shall not be
unreasonably withheld or delayed. All extra work or change order request by
Tenant shall be made in writing, shall specify the amount of delay or the time
saved resulting therefrom, shall specify any added or reduced cost resulting
therefrom and shall become effective and a part of the Approved Plans once
approved in writing by both parties.


                                      -25-
<PAGE>

           V.       Commencement and Completion of the Initial Tenant
Improvements. As soon as (a) the Approved Plans have been developed as provided
above, and (b) all necessary governmental approvals have been obtained, Landlord
shall thereafter commence construction of such improvements and shall complete
such construction in a good and workmanlike manner.

          VI.      Delay in Completion Caused by Tenant. The parties hereto
acknowledge that the date on which Tenant's obligations to pay all rent payable
under this Lease would otherwise commence, may be delayed because of, among
other things:

                  (a)      Tenant's request for special materials, finishes, or
installations which are not readily available unless contained in the approved
plans;

                  (b)      Change orders requested by Tenant and approved by
Landlord;

                  (c)      Tenant's failure to promptly review and approve the
Plans and Specifications, promptly provide information to the City regarding
Tenant's business and/or use of the premises, or to complete any of its own
improvement work to the extent Tenant delays completion by appropriate
governmental authorities of their final inspection and approval of Landlord's
improvements; or

                  (d)      Interference with Landlord's work caused by Tenant or
by Tenant's contractors or subcontractors.

         It is the intent of the parties hereto that Tenant's obligations to pay
all rent payable under this Lease may not be delayed by any of such causes or by
any other act of Tenant, and in the event it is so delayed, then Tenant's
obligation to pay such rent shall commence as of the date it would otherwise
have commenced absent said delay caused by Tenant.

         VII.     Tenant's Requirements: Tenant acknowledges that it shall
provide Landlord with certain information regarding its specific needs relating
to the Premises which shall be incorporated into the Plans and Specifications to
address those needs. Tenant also acknowledges that it may provide some of its
own equipment for installation in the Premises., Tenant understands and agrees
that Landlord will take no independent review of any such information, designs,
specifications or equipment to determine if same adequately addresses Tenant's
needs or are suitable for the Premises; and anything in this Lease to the
contrary notwithstanding, Landlord does not warrant, either expressly or
implied, the adequacy of any such designs, specifications or equipment, or the
Initial Tenant Improvements, for Tenant's intended purpose.

                                      -26-
<PAGE>

                                    EXHIBIT C

                                  SIGN CRITERIA

                                    SPINNAKER

WINDOW SIGNS IDENTIFICATION:

Each Tenant will be allowed one window sign placed either to the left or to the
right of the entrance door, whichever provides the best visibility.

Company names, logos or symbols will be allowed in this area - color and size to
be determined by the Tenant. All other copy in this area except for logos or
symbols will be matte white pressure sensitive letters.

Copy should start at 5' from grade working down to no more than 3 1/2 ' from
grade. Sign layout including copy, sizes and color must be approved by the
building management.

One security decal only may be applied to the front door glass in the lower
corner if the Tenant so desires. All exterior alarm bells are to be mounted to
the rear of the building only.

DIRECTORY SIGN IDENTIFICATION:

A monument directory sign has been provided for each building. If only one
tenant occupies an entire building, that Tenant shall be allowed to utilize the
entire directory sign area for its sensitive vinyl letters in the Handel Gothic
style in ink blue with a letter height suitable for the area allowed, and a logo
may be used.

If two or more Tenants occupy a building, signs shall consist of 4" Handel
Gothic dark blue pressure sensitive vinyl letters condensed to 60.4%. Directory
signs shall list the street number and the company names only, no slogans or
symbols allowed.

REAR LOADING SIGNS:

Each Tenant will be allowed to identify its rear door for shipping and receiving
purposes. The company name shall be placed on a 36" x 24" aluminum panel
adjacent to the rear doors.

Copy shall consist of vinyl letters only in the dark blue Handel Gothic style.
Company names and logos only are allowed. Address numbers and door designation
sign re: Shipping/Receiving, will call...will be installed centered above the
main door. Address is always on rear loading sign.

Management reserves the right to deny any copy it considers unsuitable, and must
approve all copy prior to installation. The cost of all lettering and logos is
the responsibility of the Tenant. No other signs are allowed in the windows or
doors.

                                      -27-