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  <xsd:element id="pdfs_PurchasesOfTreasuryStockSharesInConnectionWithTaxWithholdingsOnRestrictedStockGrants" name="PurchasesOfTreasuryStockSharesInConnectionWithTaxWithholdingsOnRestrictedStockGrants" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration"/>
  <xsd:element id="pdfs_ReceivablesByMajorCustomersTableTextBlock" name="ReceivablesByMajorCustomersTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_RestOfTheWorldMember" name="RestOfTheWorldMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_RestrictedStockUnitsRsuNonvestedMember" name="RestrictedStockUnitsRsuNonvestedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="pdfs_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesReservedDecreaseRate" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesReservedDecreaseRate" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_SharesPreviouslyIssuedUnderThe2001PlanMember" name="SharesPreviouslyIssuedUnderThe2001PlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_StockPlansMember" name="StockPlansMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_SyntricityMember" name="SyntricityMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="pdfs_TaxBenefitRelatedToStockbasedCompensationexpense" name="TaxBenefitRelatedToStockbasedCompensationexpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_TestEquipmentMember" name="TestEquipmentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_TwentyElevenStockIncentivePlanMember" name="TwentyElevenStockIncentivePlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_TwoCustomersMember" name="TwoCustomersMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_TwoThousandOneStockIncentivePlanMember" name="TwoThousandOneStockIncentivePlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_USAbstract" name="USAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element id="pdfs_UnrecognizedTaxBenefitsInDeferredTaxAssetSubjectToFullValuationAllowance" name="UnrecognizedTaxBenefitsInDeferredTaxAssetSubjectToFullValuationAllowance" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="pdfs_UnrecognizedTaxBenefitsInDeferredTaxAssets" name="UnrecognizedTaxBenefitsInDeferredTaxAssets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="pdfs_UnrecognizedTaxBenefitsInLongTermLiabilities" name="UnrecognizedTaxBenefitsInLongTermLiabilities" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="pdfs_UnrecordedWindfallDeductions" name="UnrecordedWindfallDeductions" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-1-business-and-significant-accounting-policies-allowance-for-doubtful-accounts-details" name="statement-statement-note-1-business-and-significant-accounting-policies-allowance-for-doubtful-accounts-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-1-business-and-significant-accounting-policies-estimated-useful-lives-of-property-and-equipment-details" name="statement-statement-note-1-business-and-significant-accounting-policies-estimated-useful-lives-of-property-and-equipment-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-1-business-and-significant-accounting-policies-reconciliation-of-adjustments-to-consolidated-balance-sheet-data-details" name="statement-statement-note-1-business-and-significant-accounting-policies-reconciliation-of-adjustments-to-consolidated-balance-sheet-data-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-1-business-and-significant-accounting-policies-reconciliation-of-adjustments-to-consolidated-statements-of-cash-flows-data-details" name="statement-statement-note-1-business-and-significant-accounting-policies-reconciliation-of-adjustments-to-consolidated-statements-of-cash-flows-data-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-1-business-and-significant-accounting-policies-reconciliation-of-adjustments-to-consolidated-statements-of-income-data-details" name="statement-statement-note-1-business-and-significant-accounting-policies-reconciliation-of-adjustments-to-consolidated-statements-of-income-data-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-1-business-and-significant-accounting-policies-tables" name="statement-statement-note-1-business-and-significant-accounting-policies-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-11-selected-quarterly-financial-data-unaudited-selected-quarterly-financial-data-unaudited-details" name="statement-statement-note-11-selected-quarterly-financial-data-unaudited-selected-quarterly-financial-data-unaudited-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-11-selected-quarterly-financial-data-unaudited-tables" name="statement-statement-note-11-selected-quarterly-financial-data-unaudited-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-2-property-and-equipment-property-and-equipment-details" name="statement-statement-note-2-property-and-equipment-property-and-equipment-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-2-property-and-equipment-tables" name="statement-statement-note-2-property-and-equipment-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-3-balance-sheet-components-annual-amortization-of-identifiable-intangible-assets-details" name="statement-statement-note-3-balance-sheet-components-annual-amortization-of-identifiable-intangible-assets-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-3-goodwill-and-intangible-assets-goodwill-activity-details" name="statement-statement-note-3-goodwill-and-intangible-assets-goodwill-activity-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-3-goodwill-and-intangible-assets-intangible-assets-details" name="statement-statement-note-3-goodwill-and-intangible-assets-intangible-assets-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-3-goodwill-and-intangible-assets-tables" name="statement-statement-note-3-goodwill-and-intangible-assets-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-4-commitments-and-contingencies-future-minimum-lease-payments-under-noncancelable-operating-leases-details" name="statement-statement-note-4-commitments-and-contingencies-future-minimum-lease-payments-under-noncancelable-operating-leases-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-4-commitments-and-contingencies-tables" name="statement-statement-note-4-commitments-and-contingencies-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-5-stockholders-equity-allocation-of-recognized-period-costs-details" name="statement-statement-note-5-stockholders-equity-allocation-of-recognized-period-costs-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-5-stockholders-equity-nonvested-restricted-stock-units-activity-details" name="statement-statement-note-5-stockholders-equity-nonvested-restricted-stock-units-activity-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-5-stockholders-equity-stock-options-activity-details" name="statement-statement-note-5-stockholders-equity-stock-options-activity-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-5-stockholders-equity-stock-options-valuation-assumptions-details" name="statement-statement-note-5-stockholders-equity-stock-options-valuation-assumptions-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-5-stockholders-equity-tables" name="statement-statement-note-5-stockholders-equity-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-6-income-taxes-deferred-tax-assets-details" name="statement-statement-note-6-income-taxes-deferred-tax-assets-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-6-income-taxes-income-tax-expense-benefit-details" name="statement-statement-note-6-income-taxes-income-tax-expense-benefit-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-6-income-taxes-income-tax-reconciliation-details" name="statement-statement-note-6-income-taxes-income-tax-reconciliation-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-6-income-taxes-tables" name="statement-statement-note-6-income-taxes-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-6-income-taxes-unrecognized-tax-benefits-details" name="statement-statement-note-6-income-taxes-unrecognized-tax-benefits-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-6-income-taxes-valuation-allowance-of-deferred-tax-assets-details" name="statement-statement-note-6-income-taxes-valuation-allowance-of-deferred-tax-assets-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-7-net-income-per-share-antidilutive-securities-details" name="statement-statement-note-7-net-income-per-share-antidilutive-securities-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-7-net-income-per-share-calculation-of-earnings-per-share-details" name="statement-statement-note-7-net-income-per-share-calculation-of-earnings-per-share-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-7-net-income-per-share-tables" name="statement-statement-note-7-net-income-per-share-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-8-customer-and-geographic-information-longlived-assets-by-geographic-area-details" name="statement-statement-note-8-customer-and-geographic-information-longlived-assets-by-geographic-area-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-8-customer-and-geographic-information-receivables-percentage-by-major-customers-details" name="statement-statement-note-8-customer-and-geographic-information-receivables-percentage-by-major-customers-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-8-customer-and-geographic-information-revenue-percentage-by-major-customers-details" name="statement-statement-note-8-customer-and-geographic-information-revenue-percentage-by-major-customers-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-8-customer-and-geographic-information-revenues-by-geographic-area-details" name="statement-statement-note-8-customer-and-geographic-information-revenues-by-geographic-area-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-8-customer-and-geographic-information-tables" name="statement-statement-note-8-customer-and-geographic-information-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-9-financial-instruments-fair-value-assets-measured-on-a-recurring-basis-details" name="statement-statement-note-9-financial-instruments-fair-value-assets-measured-on-a-recurring-basis-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-note-9-financial-instruments-tables" name="statement-statement-note-9-financial-instruments-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="pdfs_statement-statement-significant-accounting-policies-policies" name="statement-statement-significant-accounting-policies-policies" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
</xsd:schema>