<PAGE>
                                                                   EXHIBIT 10.22

                        FOURTH AMENDMENT TO OFFICE LEASE
                       (Amending the Seventh Floor Lease)

                                       and

                            SECOND AMENDMENT TO LEASE
                        (Amending the Fifth Floor Lease)

      This Fourth Amendment to Office Lease and Second Amendment to Lease
(collectively, the "Amendment") is entered into, and dated for reference
purposes, as of March 19, 2003 (the "Execution Date") by and between
METROPOLITAN LIFE INSURANCE COMPANY, a New York corporation ("Metropolitan"), as
Landlord ("Landlord"), and PDF Solutions, Inc., a Delaware corporation ("PDF"),
as Tenant ("Tenant"), with reference to the following facts ("Recitals"):

      A. Landlord and Tenant are the parties to that certain lease of the entire
seventh floor (the "Seventh Floor Premises") of the building whose current
street address is 333 West San Carlos Street, San Jose, California 95110 (the
"Building"), all as described in the lease, which lease is comprised of the
following: written lease (including, without limitation, the Addendum thereto)
dated for reference purposes as of April 1, 1996 between Landlord and Tenant's
predecessor-in-interest (PDF Solutions, Inc., a California corporation) (the
"Original Lease"), as amended by that written amendment dated for reference
purposes as of February 10, 1997 (the "First Amendment"), written amendment
dated for reference purposes as of July 11, 1997 (the "Second Amendment") and
written amendment dated for reference purposes as of August 17, 1999 (the "Third
Amendment"), which collectively, as amended, is referred to herein as the
"Existing Lease" or the "Seventh Floor Lease").

      B Landlord and Tenant are also the parties to that certain lease of the
entire fifth floor (the "Fifth Floor Premises") of the Building, all as
described in the lease, which lease is comprised of the following: Letter dated
February 20, 2002 from Metropolitan to PDF exercising Metropolitan's option that
PDF attorn to Metropolitan as set forth therein; Metropolitan's consent to
sublease by letter dated April 6, 2001 (which letter was addressed to Calico
Commerce, Inc. ("Calico") as Prime Tenant, signed and agreed to by all of PDF,
Calico and Metropolitan); Sublease dated March 14, 2001 between Calico and PDF
(the "Sublease"); the Office Lease between Metropolitan and Calico, dated August
18, 1999, as amended as of September 7, 2000 (as amended, the "Master Lease");
and the Amendment to Lease dated as of August 9, 2002 between Landlord and
Tenant's predecessor-in-interest (PDF Solutions, Inc., a California corporation)
(which reference to Tenant's predecessor was due to clerical error).
Collectively, the lease of the Fifth Floor Premises, as amended, is referred to
herein as the "Fifth Floor Lease".

      C. Landlord and Tenant desire to amend both the Fifth Floor Lease and the
Seventh Floor Lease to consolidate both the Fifth Floor Premises and the Seventh
Floor Premises into one lease under the Seventh Floor Lease (also referred to as
the Existing Lease) for a modified and extended Term, and to provide for other
amendments, as more particularly set forth below.

      Section 1. Scope of Amendment; Defined Terms; Retroactive Effect; Tenant's
Interest under the Leases.

            (a) Except as expressly provided in this Amendment, the Existing
Lease shall remain in full force and effect. Except as expressly provided in
this Amendment, the Fifth Floor Lease shall remain in full force and effect as
to the period through the Fifth Floor Lease Early Termination Date (defined
below). Should any inconsistency arise between this Amendment and the Existing
Lease as to the specific matters which are the subject of this Amendment, the
terms and conditions of this Amendment shall control. The term "Existing Lease"
defined above shall refer to the Existing Lease as it existed before giving
effect to the modifications set forth in this Amendment and the term "Lease" as
used herein and in the Existing Lease shall refer to the Existing Lease as
modified by this Amendment. All capitalized terms used in this Amendment and not
defined herein shall have the meanings set forth in the Existing Lease unless
the context clearly requires otherwise. Tenant and Landlord acknowledge that
they have executed this Amendment as of the Execution Date set forth above, but
intend and agree that this Amendment shall be effective as of January 31, 2003
with the same force and effect as if executed on that date. Landlord
acknowledges that prior to the Execution Date Tenant has paid rent for February
at the rates applicable under the Existing Lease and Fifth Floor Lease and that
before the Execution Date Tenant may have paid rent for March. Tenant shall be
entitled to credit against the rents due and becoming due under the Lease the
amount (if any) by which the rents actually paid by Tenant for February and
March, 2003 exceeded the rents payable under the Lease for such period, and
Tenant shall pay Landlord within ten days after notice from Landlord the amount
(if any) by which the rents actually paid by Tenant for February and March, 2003
underpaid the rents payable under the Lease for such period.

            (b) PDF Solutions, Inc., a Delaware corporation ("PDF") represents
and warrants and agrees that: (i) PDF occupies the Seventh Floor Premises and
the Fifth Floor Premises and is the Tenant under the Existing Lease and the
Fifth Floor Lease; (ii) PDF is the successor by merger to PDF Solutions, Inc, a
California corporation ("PDF California") and as such is the surviving
corporation after such merger, and assignee of or successor to the interest of
PDF California under the Existing Lease and the Fifth Floor Lease, and has
assumed, or hereby assumes, the obligations of PDF California under the Existing
Lease and the Fifth Floor Lease, and holds all right, title and interest of PDF
California and of the Tenant (as such term is defined and used in each of the
Existing Lease and the Fifth Floor Lease) under the Existing Lease and the Fifth
Floor Lease; (v) has not entered into any assignment of the Existing Lease or
the Fifth Floor Lease, and no sublease or other agreement for use or occupancy
of the Seventh Floor Premises or Fifth Floor Premises or any part of either is
in effect. Tenant's obligations with respect to the representations, warranties
and agreements under this Section survive the expiration or sooner termination
of the Term of this Lease.

            Section 2. Modification and Early Termination of Term of the Fifth
Floor Lease. Landlord and Tenant acknowledge and agree that, before giving
effect to this Amendment, pursuant to the Fifth Floor Lease, the Expiration Date
of the Term of the Fifth Floor Lease is May 7, 2003. Notwithstanding any
provision of the Fifth Floor Lease to the contrary, the Fifth Floor Lease is
hereby amended to provide that the Expiration Date of the Term of the Fifth
Floor Lease shall be January 31, 2003 (Fifth Floor Lease Early Termination Date)
instead of any later date pursuant to its original terms, and the Fifth Floor
Lease shall expire and terminate at midnight, January 31, 2003, including
termination of any options or rights to extend or renew and all other options or
rights, if any, provided in the Fifth Floor Lease, and


                                       1
<PAGE>
all rights and obligations with respect to rent thereunder shall be prorated on
the basis of such early expiration and termination, except as otherwise provided
herein with respect to the security deposit.

            Section 3. Modification and Extension of Term of the Seventh Floor
Lease. Landlord and Tenant acknowledge and agree that, before giving effect to
this Amendment, pursuant to the Existing Lease, the Expiration Date of the Term
of the Existing Lease is October 31, 2004. Notwithstanding any provision of the
Existing Lease to the contrary, the Existing Lease is hereby amended to provide
that the Expiration Date of the Term of the Existing Lease shall be January 31,
2003 instead of October 31, 2004, and then this Lease shall be for a term of
five (5) years (the "Extended Term") beginning at midnight local time at the
Building on February 1, 2003 (the "Extended Term Commencement Date") and
expiring at midnight local time on January 31, 2008 (hereafter, the "Expiration
Date" with respect to the Extended Term), unless sooner terminated pursuant to
the terms of the Lease, and the Demised Premises for the Extended Term shall be
both the Seventh Floor Premises and Fifth Floor Premises, as described in
Section 5 below. Landlord and Tenant acknowledge and agree that this Amendment
provides all rights and obligations of the parties with respect to extension of
the Term, whether or not in accordance with any other provisions, if any, of the
Existing Lease regarding renewal or extension, and any such provisions, options
or rights for renewal or extension provided in the Existing Lease are hereby
deleted as of the Execution Date.

            Section 4. Deletion of Prior Amendments. For purposes of this
Amendment, the "Prior Amendments" shall mean the First Amendment, Second
Amendment and Third Amendment of the Existing Lease. Effective on the Extended
Term Commencement Date (defined above), the "Prior Amendments" are deleted and
shall not be part of the "Lease" , and shall have no further effect except with
respect to any remaining determinations of the rights, claims and obligations of
the parties for the period prior to February 1, 2003 with respect to the Seventh
Floor Premises.

            Section 5. Demised Premises; Tenant's Share of Taxes & Operating
Costs. Article L of Section I of the Original Lease is hereby deleted and
amended as follows, and Articles F and K are hereby amended as follows, and
notwithstanding any provision of the Existing Lease to the contrary, for the
Extended Term:

            (a) Demised Premises. The Demised Premises leased to and by Tenant
shall mean the Seventh Floor Premises together with the Fifth Floor Premises,
which shall be conclusively presumed to be the Rentable Area set forth below:

<TABLE>
<S>                                         <C>
               Fifth Floor Premises:        19,548 square feet of Rent
               Seventh Floor Premises:      19,548 square feet
               Demised Premises Total:      39,096 square feet
</TABLE>

            (b) Base Year; Tenant's Share of Taxes and Operating Costs. Tenant
shall pay Tenant's Share of Taxes and Operating Costs in excess of the Base
Taxes and Operating Costs Amount, and for such calculation, it is conclusively
agreed that: (i) Tenant's Share is 13.274%; (ii) the Rentable Area of the
Building is 294,532 square feet; and (iii) the Base Taxes and Operating Costs
Amount is the amount of Taxes and Operating Costs for calendar year 2002.

      Section 6. Base Annual Rent. Article H of Section I of the Original Lease
is hereby amended as follows, and notwithstanding any provision of the Existing
Lease to the contrary, for the Extended Term, Base Annual Rent and Monthly
Installments thereof due and payable (in the manner required under the Lease for
Monthly Installments of Base Annual Rent) by Tenant for the Extended Term shall
be as follows:

<TABLE>
<CAPTION>
      Period from/through      Monthly Installment   Annual Rate/sq. ft. of Rentable Area
      -------------------      -------------------   ------------------------------------
<S>                            <C>                   <C>
      Month 01 - Month 12      $109,143.00                         $33.50
      Month 13 - Month 24      $114,030.00                         $35.00
      Month 25 - Month 36      $118,917.00                         $36.50
      Month 37 - Month 48      $123,804.00                         $38.00
      Month 49 - Month 60      $128,691.00                         $39.50
</TABLE>

      Section 7. Parking. Notwithstanding any provision of the Existing Lease to
the contrary, during the Extended Term, Tenant shall have the right to use on an
unassigned basis ninety-four (94) parking spaces and for such right shall pay
Landlord, as additional Rent in the same manner as for payment of Monthly
Installments of Base Annual Rent, a total per month (prorated for any partial
month(s) during such period) calculated at Landlord's prevailing rate for
unassigned spaces; provided that Landlord's prevailing rate charged to Tenant
shall not be increased at a rate greater than 3.25% per year following the
Extended Term Commencement Date.

      Section 8. Security Deposit. Article M of Section I of the Original Lease
is hereby amended as follows, and notwithstanding any provision of the Existing
Lease to the contrary, for the Extended Term the amount of the Security Deposit
required under the Lease shall be One Hundred Forty-five Thousand Six Hundred
and Thirty-two and 60/100 Dollars ($145,632.60). Landlord and Tenant acknowledge
and agree that such amount is the combined total of the Security Deposit
required under the Seventh Floor Lease ($57,666.60) plus that required under the
Fifth Floor Lease ($87,966.00), and that Landlord shall transfer and credit
toward that combined amount, such balance of the Security Deposit held under the
Fifth Floor Lease which is not applied to any default of Tenant under the Fifth
Floor Lease.

      Section 9. Computer Room; Supplemental Cooling System; Supplemental
Cooling Equipment.

            (a) Landlord and Tenant acknowledge and agree that Tenant desires to
locate certain computer servers and equipment (and/or other heat generating
equipment) in a room ("Computer Room") within the Demised Premises. Landlord
will allow such Computer Room provided that Tenant installs and operates a
"Supplemental Cooling System" (defined below) to cool the Computer Room. Tenant
shall have the right, at Tenant's sole cost and expense, and subject to
Landlord's reasonable approval of the plans and specifications for, and
installation of, a Supplemental Cooling System, to install, operate and maintain
a Supplemental Cooling System. Such right is further subject to all the
additional terms and conditions set forth below. The term "Supplemental Cooling
System" shall mean a supplemental cooling system for the Computer Room which
meets all of the following requirements: (1) has sufficient capacity to cool the


                                       2
<PAGE>
Computer Room; (2) is separate from the Building's HVAC systems and shall not
adversely affect the operation, maintenance or replacement of any Building HVAC
system; (3) is capable of independent 24 hour operation daily; (4) does not,
together with all other electrical loads of Tenant, exceed the capacity of the
electrical circuits and equipment providing electrical power to the Demised
Premises; and (5) is wholly contained within the Demised Premises, except as
otherwise provided in Subsection (b) below.

            (b) In meeting Tenant's obligation to provide a Supplemental Cooling
System, Tenant shall have the right to use the "Supplemental Cooling Equipment"
(defined below) and the additional area, to the extent available in the
Building's existing pathways for utilities, necessary to connect the
Supplemental Cooling Equipment to the Demised Premises from its existing
terminal point (on the 8th floor of the Building), subject to Landlord's prior
written approval of such additional area to be used and such connections, and
further subject to the terms and conditions set forth below.

            (c) For purposes of this Amendment, the term "Supplemental Cooling
Equipment" shall mean the following:

                  (i) The existing equipment mounted on the Building's roof
            adjacent to the penthouse at column 7 between columns D and E, and
            which is described as follows:

                       one (1) Liebert Model DSC Dyrcooler and one
                       (1) associated pump

                       one (1) Liebert Model DDC Dyrcooler and two
                       (2) associated pumps

                  (ii) The existing associated devices, wiring and piping which
            extends from such roof equipment down to the 8th floor mechanical
            room, and the existing electrical connections and controls for such
            equipment; provided however, Tenant shall relocate any of such
            associated devices, wiring, piping and equipment, which are now
            located in the 8th floor mechanical room or elsewhere on the 8th
            floor, to a location within the Demised Premises.

            (d) Tenant acknowledges and agrees that the Supplemental Cooling
Equipment was installed and used by a former occupant, and that Tenant has
requested to use it and is accepting it in its "As Is" condition, as more
particularly provided in Section 10 below.

            (e) Tenant shall pay all costs and expenses of all of the following
(but items (1) and (2) are reimbursable out of funds in the "Landlord's Maximum
Contribution" pursuant to Section 10 below): (1) providing and installing
equipment, wiring and piping to connect to the Supplemental Cooling Equipment,
the Building's electrical supply, the Building's water supply (if applicable)
and the Building's condenser water supply and return lines (if applicable); (2)
providing and installing separate meter(s) for Tenant's usage of electricity,
water and condenser water for operation of the Supplemental Cooling System; (3)
operation, maintenance, repair and replacement of the foregoing; (4) all costs
of electricity, water and condenser water used in operation of the Supplemental
Cooling System. Landlord may, in its discretion, require that such usage be
separately metered or Landlord may reasonably estimate the amount and cost of
such usage. In the event of failure or malfunction of any such meter(s), Tenant
shall promptly repair or replace such failed or malfunctioning meter(s), and for
any period of failure or malfunction, Landlord may estimate Tenant's usage and
bill Tenant therefor. All installations contemplated by this Section, and the
plans and specifications therefor, shall be part of the Work described in
Section 10 if done prior to July 31, 2003 and, if done thereafter, shall be
Tenant Alterations subject to Article 4 of the Original Lease. Tenant shall not
have any right to remove the Supplemental Cooling System upon expiration or
earlier termination of the Extended Term, and the Supplemental Cooling System
shall be (and the Supplemental Cooling Equipment shall remain) the property of
Landlord.

      Section 10. As Is Condition; Alterations by Tenant; Landlord's Maximum
Contribution.

            (a) Notwithstanding any provision of the Existing Lease to the
contrary, Tenant acknowledges and agrees that: (1) Tenant has been in occupancy
of the Demised Premises; (2) Tenant has been afforded ample opportunity to
inspect the Supplemental Cooling Equipment and the Demised Premises, and has
investigated their condition to the extent Tenant desires to do so; (3) Tenant
is leasing the Demised Premises in its "As Is" condition and using the
Supplemental Cooling Equipment in its "As Is" condition; (4) no representation
regarding the condition of the Demised Premises or the Supplemental Cooling
Equipment has been made by or on behalf of Landlord; and (5) Landlord has no
obligation to remodel or to make any repairs, alterations or improvements in
connection with Tenant's occupancy, use or this Amendment, and Landlord has no
obligation to provide Tenant any allowance for any work in connection with the
Demised Premises or the Supplemental Cooling Equipment, except to the extent
provided in Subsection (e) below.

            (b) Notwithstanding any provision of the Lease to the contrary,
Landlord and Tenant acknowledge and agree that: (1) Tenant desires to make
certain improvements and alterations to build a Computer Room in the Demised
Premises on the Building's fifth floor and to adapt and connect the Supplemental
Cooling Equipment for Tenant's use in connection therewith (collectively, the
"Work"); (2) that such Work shall be done by Tenant as Tenant alterations within
the meaning of Article 4 of the Original Lease (referred to in this Amendment as
"Tenant Alterations") and pursuant to provisions of the Original Lease
applicable to Tenant Alterations except as otherwise provided in this Amendment;
(3) such Work, including all design, plan review, obtaining all approvals and
permits, construction, a construction administration fee to Landlord equal to
one percent (1%) of the total cost of the work ("Administration Fee"), and
delivery to Landlord of plans and specifications (including final as-built plans
and specifications of the Work, and if requested by Landlord, an as-built mylar
and one digitized set of the plans and specifications), shall be at Tenant's
sole cost and expense, except to the extent provided in Subsection (e) below;
(4) if the aggregate cost of the Work does not exceed Landlord's Maximum
Contribution, Tenant shall not be obligated to provide a completion and lien
indemnity bond for such work; and (5) Tenant shall pay all costs and expenses of
the Work subject to reimbursement to the extent the Landlord's Maximum
Contribution is available pursuant to Subsection (e) below. Notwithstanding any
provision of the Lease to the contrary, and notwithstanding any approval by
Landlord of the Work to be done, Tenant, at Tenant's sole cost and expense,
shall remove all of the Work no later than expiration or earlier termination of
the Lease unless and except to the extent that Landlord specifically agrees in
writing to allow some or all of the Work to remain. Tenant shall restore any
area damaged by any permitted or required removal or shall pay Landlord an
amount equal to Landlord's reasonable estimate of restoration costs.


                                       3
<PAGE>
            (c) Tenant may select the general contractor to construct the Work
in the Demised Premises from an approved list of contractors provided by
Landlord.

            (d) Tenant shall be responsible for the suitability for the Tenant's
needs and business of the design and function of all such Work and for their
construction in compliance with all laws, rules, orders, ordinances, directions,
regulations and requirements pertaining to the Demised Premises, the
Supplemental Cooling Equipment and Tenant's use thereof, as applicable and as
interpreted at the time of construction of the Work, including all building
codes and the Americans With Disabilities Act of 1990, as amended (the "ADA").
Tenant, through its architects, space planners, engineers and design-build
contractors ("Tenant's Architect"), shall prepare all architectural plans and
specifications, and engineering plans and specifications, for the real property
improvements to be constructed by Tenant in the Demised Premises and with
respect to the Supplemental Cooling Equipment in sufficient detail to be
submitted for approval by Landlord pursuant to Article 4 of the Lease and to be
submitted by Tenant for governmental approvals and building permits and to serve
as the detailed construction drawings and specifications for the contractor, and
shall include, among other things, all partitions, doors, HVAC (heating,
ventilating and air conditioning systems) distribution, ceiling systems, light
fixtures, plumbing installations, electrical installations and outlets,
telephone installations and outlets, any other installations required by Tenant,
fire and life-safety systems, wall finishes and floor coverings, whether to be
newly installed or requiring changes from the As-Is condition of the Demised
Premises or of the Supplemental Cooling Equipment as of the date of execution of
this Amendment. Tenant shall be responsible for the oversight, supervision and
construction of all Work in compliance with this Lease, including compliance
with all Law as applicable and as interpreted at the time of construction.

            (e) Landlord's Maximum Contribution means an amount up to a maximum
of Two Hundred Fifty Thousand Dollars ($250,000.00). Landlord's Maximum
Contribution shall be payable as provided below and shall be used solely as
follows: (1) to pay the Administration Fee to Landlord, the amount of which
Landlord may deduct from the Landlord's Maximum Contribution and retain in
payment of the Administration Fee; and (2) to reimburse Tenant for the actual
costs of design, space planning and working drawings, services for electrical,
mechanical, plumbing and structural engineering services, plan review, obtaining
all approvals and permits, licenses, fees, construction management and
construction of Work. In no event shall the Landlord's Maximum Contribution be
used to reimburse any costs of designing, procuring or installing in the Demised
Premises any trade fixtures, movable equipment, furniture, furnishings,
telephone equipment, or other personal property (collectively "Personal
Property" for purposes of this Amendment) to be used in the Demised Premises by
Tenant, and the cost of such Personal Property shall be paid by Tenant.
Landlord's Maximum Contribution shall be paid to Tenant within thirty (30) days
after the later of final completion of the Tenant Work and Landlord's receipt of
(i) a certificate of occupancy (if applicable), (ii) final as-built plans and
specifications of the Work (if requested by Landlord, including an as-built
mylar and one digitized set of the plans and specifications), (iii) full, final,
unconditional lien releases from all contractors and subcontractors, and (iv)
reasonable substantiation of costs incurred by Tenant with respect to the Work.
Tenant must prior to July 31, 2003 submit written application with the items
required above for disbursement or reimbursement for any reimbursable costs out
of the Landlord's Maximum Contribution, and to the extent of any funds for which
application has not been made prior to that date or if and to the extent that
the reimbursable costs of the Tenant Work are less than the amount of Landlord's
Maximum Contribution, then Landlord shall retain the unapplied or unused balance
of the Landlord's Maximum Contribution and shall have no obligation or liability
to Tenant with respect to such excess.

      Section 11. Assignment, Mortgage, Subletting. Notwithstanding any
provision of the Existing Lease to the contrary, as previously provided in the
Third Amendment, for the Extended Term

            (a) Subsection 3.1(5) of Section 3.1 of the Original Lease is hereby
      deleted.

            (b) Subsection 3.2 of the Original Lease is deleted in its entirety,
      and the following substituted therefor:

            "3.2. Tenant shall pay Landlord on the first day of each month
      during the term of the sublease or assignment fifty percent (50%) of the
      amount by which the sum of all rent and other consideration (direct or
      indirect) due from the subtenant or assignee for such month exceeds: (i)
      that portion of the Monthly Installments of Base Annual Rent and rental
      adjustments due under this Lease for said month which is allocable to the
      space sublet or assigned; and (ii) the following costs and expenses for
      the subletting or assignment of such space: (1) brokerage commissions and
      attorneys' fees and expenses, and (2) the actual costs paid in making any
      improvements or substitutions in the Demised Premises required by any
      sublease or assignment. All such costs and expenses shall be amortized
      over the term of the sublease or assignment pursuant to sound accounting
      principles. Vacancy period costs and expenses, including rent paid by
      Tenant during any vacancy, do not qualify as costs or expenses under item
      (ii) above."

      Section 12. Option to Extend.

            (i) Landlord hereby grants Tenant a single option to extend the
Extended Term of the Lease for an additional period of five (5) years (such
period may be referred to as the "Option Term"), as to the entire Demised
Premises as it may then exist, upon and subject to the terms and conditions of
this Section (the "Option To Extend"), and provided that at the time of exercise
of such right: (i) Tenant must be in occupancy of the entire Demised Premises;
and (ii) Tenant has a net worth sufficient to allow it to timely honor all of
its financial obligations thereunder at the time of the exercise.

            (ii) Tenant's election (the "Election Notice") to exercise the
Option To Extend must be given to Landlord in writing no earlier than February
1, 2007 and no later than May 1, 2007. If Tenant either fails or elects not to
exercise its Option to Extend by not timely giving its Election Notice, then the
Option to Extend shall be null and void.

            (iii) The Option Term shall commence immediately after the
expiration of the Extended Term of the Lease specified in Section 3 of this
Amendment. Tenant's leasing of the Demised Premises during the Option Term shall
be upon and subject to the same terms and conditions contained in the Lease
except that (i) the Base Annual Rent and, if applicable, the Base Taxes and
Operating Costs Amount shall be amended to equal the "Option Term Rent", defined
and determined in the manner set forth in the immediately following Subsection;
(ii) Tenant shall accept the Demised Premises in its "as is" condition without
any obligation of Landlord to repaint, remodel, repair, improve or alter the
Demised Premises or to provide Tenant any allowance therefor;


                                       4
<PAGE>
and (iii) there shall be no further option or right to extend the term of the
Lease. If Tenant timely and properly exercises the Option To Extend, references
in the Lease to the Term shall be deemed to mean the initial Term as extended by
the Option Term unless the context clearly requires otherwise.

            (iv) The Option Term Rent shall mean the greater of (i) the Annual
Base Rent plus Tenant's then current Tenant's Share of Taxes and Operating Costs
in excess of the Base Taxes and Operating Costs Amounts for calendar year 2002
(collectively, "Preceding Rent") or (ii) the "Prevailing Market Rent". As used
herein Prevailing Market Rent shall mean the rent and all other monetary
payments paid by tenants in connection with the use and occupancy of their
premises that are then "market" (such as, for example, charges for after hours
HVAC) and escalations, including consumer price increases, that Landlord could
obtain from a third party desiring to lease the Demised Premises for a term
equal to the Option Term, as second generation space, and commencing when the
Option Term is to commence under market leasing conditions; provided however
Prevailing Market Rent shall take into account the following: the size, location
and floor levels of the Demised Premises; the type and quality of tenant
improvements; age and location of the Building; quality of construction of the
Building; services to be provided by Landlord or by tenant; and other factors
that would be relevant to such a third party in determining what such party
would be willing to pay therefor, all based upon comparable class A office
buildings in San Jose; provided, however, that Prevailing Market Rent shall be
determined without reduction or adjustment for "Tenant Concessions" (as defined
below), if any, being offered to prospective new tenants of comparable space.
For purposes of the preceding sentence, the term "Tenant Concessions" shall
include, without limitation, "free rent", tenant improvement allowances and
work, moving allowances, and lease takeovers. The determination of Prevailing
Market Rent based upon the foregoing criteria shall be made by Landlord, in the
good faith exercise of Landlord's business judgment. Within thirty (30) days
after Tenant's exercise of the Option To Extend, Landlord shall notify Tenant of
Landlord's determination of Option Term Rent for the Demised Premises. If,
within five (5) days after Landlord notifies Tenant of Landlord's determination
of Option Term Rent, Tenant does not accept Landlord's determination, Tenant
shall so notify Landlord of Tenant's non-acceptance. Tenant shall then have the
opportunity, within a period of twenty (20) days following the date Tenant
notifies Landlord of Tenant's non-acceptance, to discuss with and request from
Landlord a redetermination of Option Term Rent, with Tenant's acceptance, if
any, of a redetermined Option Term Rent to be confirmed in writing during such
twenty (20) day period. If Landlord does not offer a redetermined Option Term
Rent, or Landlord and Tenant cannot agree upon an Option Term Rent for any
reason or no reason whatsoever, then Tenant may notify Landlord no later than
the expiration of the twenty (20) day period, that Tenant is rescinding Tenant's
exercise of the Option to Extend. Upon such rescission, the Option to Extend
shall become null and void. If Tenant does not notify Landlord of its rescission
of the exercise of the Option to Extend within such twenty (20) day period, then
Tenant shall be deemed to have exercised the Option to Extend at the Option Term
Rent originally determined by Landlord, or the agreed-upon redetermined Option
Term Rent, as applicable.

            (v) This Option to Extend is personal to PDF Solutions, Inc. and may
not be used by, and shall not be transferable or assignable (voluntarily or
involuntarily) to any person or entity.

            (vi) Upon the occurrence of any of the following events, Landlord
shall have the option, exercisable at any time prior to commencement of the
Option Term, to terminate all of the provisions of this Section with respect to
the Option to Extend, with the effect of canceling and voiding any prior or
subsequent exercise so this Option to Extend is of no force or effect:

                  a. Tenant's failure to timely exercise the Option to Extend in
      accordance with the provisions of this Section.

                  b. The existence at the time Tenant exercises the Option to
      Extend or at the commencement of the Option Term of any default on the
      part of Tenant under the Lease or of any state of facts which with the
      passage of time or the giving of notice, or both, would constitute such a
      default.

                  c. Tenant's third monetary default under the Lease prior to
      the commencement of the Option Term, notwithstanding that all such
      monetary defaults may subsequently be cured.

In the event of Landlord's termination of the Option to Extend pursuant to
Section 12 (vi) b. or c., Tenant shall reimburse Landlord for all reasonable
costs and expenses Landlord incurs in connection with Tenant's exercise of the
Option to Extend including, without limitation, costs and expenses with respect
to any brokerage commissions and attorneys' fees, and with respect to the
design, construction or making of any tenant improvements, repairs or renovation
or with respect to any payment of all or part of any allowance for any of the
foregoing.

            (vii) Without limiting the generality of any provision of the Lease,
time shall be of the essence with respect to all of the provisions of this
Section.

      Section 13. Brokers. Notwithstanding any other provision of the Lease to
the contrary, Tenant represents and warrants to Landlord that CB Richard Ellis,
as Landlord's broker, is the sole broker who negotiated and brought about the
consummation of this Amendment and that no discussions or negotiations were had
with any other broker concerning this Amendment. Based on the foregoing
representation and warranty, Landlord has agreed to pay any commission or fee
owed to such broker in connection with this Amendment pursuant to Landlord's
agreement between Landlord and such broker. Tenant hereby indemnifies and agrees
to protect, defend and hold Landlord harmless from and against any claims of
brokerage commissions arising out of any discussions or negotiations allegedly
had by Tenant with any other broker in connection with the Building and the
Demised Premises. The foregoing obligations of Tenant shall survive the
expiration or sooner termination of the Lease.

      Section 14. Change of Address for Copies of Notices to Landlord. Section
27.1 of the Original Lease is hereby amended to provide that (a) an additional
method of sending notices which either party desires or is required to give the
other is via reputable overnight national delivery service maintaining records
of receipts, delivery and attempts at delivery, and (b) the current addresses
for notices to be sent to Landlord pursuant to the Lease are modified as
follows:


                                       5
<PAGE>
               Metropolitan Life Insurance Company
               c/o Office of the Building Manager
               333 West San Carlos Street
               Attention:  Building Manager

               with copies to the following:

                      Metropolitan Life Insurance Company
                      400 South El Camino Real, Suite 800
                      San Mateo, CA 94402
                      Attention: Director - Regional Manager, Real Estate
                                 Investments

                                    and

                      Metropolitan Life Insurance Company
                      400 South El Camino Real, Suite 800
                      San Mateo, CA  94402
                      Attention: Associate General Counsel

      Section 15. Time of Essence. Without limiting the generality of any other
provision of the Existing Lease, time is of the essence to each and every term
and condition of this Amendment.

      Section 16. Attorneys' Fees. Notwithstanding any provision of the Existing
Lease to the contrary: (a) each party to this Amendment shall bear its own
attorneys' fees and costs incurred in connection with the discussions preceding,
negotiations for and documentation of this Amendment; and (b) in the event any
party brings any suit or other proceeding with respect to the subject matter or
enforcement of this Amendment or the Lease, the prevailing party (as determined
by the court, agency or other authority before which such suit or proceeding is
commenced) shall, in addition to such other relief as may be awarded, be
entitled to recover attorneys' fees, expenses and costs of investigation as
actually incurred, including court costs, expert witness fees, costs and
expenses of investigation, and all attorneys' fees, costs and expenses in any
such suit or proceeding (including in any action or participation in or in
connection with any case or proceeding under the Bankruptcy Code, 11 United
States Code Sections 101 et seq., or any successor statutes, in establishing or
enforcing the right to indemnification, in appellate proceedings, or in
connection with the enforcement or collection of any judgment obtained in any
such suit or proceeding).

      Section 17. Effect of Headings. The titles or headings of the various
parts or sections hereof are intended solely for convenience and are not
intended and shall not be deemed to or in any way be used to modify, explain or
place any construction upon any of the provisions of this Amendment.

      Section 18. Entire Agreement; Amendment. This Amendment taken together
with the Existing Lease, together with all exhibits, schedules, riders and
addenda to each, constitutes the full and complete agreement and understanding
between the parties hereto and shall supersede all prior communications,
representations, understandings or agreements, if any, whether oral or written,
concerning the subject matter contained in this Amendment and the Existing
Lease, as so amended, and no provision of the Lease as so amended may be
modified, amended, waived or discharged, in whole or in part, except by a
written instrument executed by all of the parties hereto.

      Section 19. Authority. Each person executing this Amendment represents and
warrants that he or she is duly authorized and empowered to execute it, and does
so as the act of and on behalf of the party indicated below.

      Section 20. Counterparts. This Amendment may be executed in duplicates or
counterparts, or both, and such duplicates or counterparts together shall
constitute but one original of the Amendment. Each duplicate and counterpart
shall be equally admissible in evidence, and each original shall fully bind each
party who has executed it.


                                       6
<PAGE>
      Section 21. Facsimile Signatures. In order to expedite the transaction
contemplated herein, telecopied signatures may be used in place of original
signatures on this Amendment. Tenant and Landlord intend to be bound by the
signatures on the telecopied document, are aware that the other party will rely
on the telecopied signatures, and hereby waive any defenses to the enforcement
of the terms of this Amendment based on the form of signature.

      IN WITNESS WHEREOF, the parties hereto have executed this Amendment as of
the date first set forth above.

      TENANT:              PDF SOLUTIONS, INC.,
                           a Delaware corporation


                           By:    /s/ John K. Kibarian
                              --------------------------------------------------

                                  Print Name: John K. Kibarian

                                  Title: President and Chief Executive Officer
                                        ----------------------------------------
                                  (Chairman of Board, President or Vice
                                  President)


                           By: /s/ P. Steven Melman
                              --------------------------------------------------

                                  Print Name: P. Steven Melman

                                  Title: Chief Financial Officer
                                        ----------------------------------------
                                  (Secretary, Assistant Secretary, CFO or
                                   Assistant Treasurer)

      LANDLORD:            METROPOLITAN LIFE INSURANCE COMPANY,
                           a New York corporation


                           By: /s/ Bill J. Fitzgerald
                              --------------------------------------------------

                                  Print Name: Bill J. Fitzgerald

                                  Title: Assistant Vice President
                                        ----------------------------------------


                                       7