钽电容和陶瓷电容的比较.pdf

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1、TANTALUMTantalumvs.Ceramiccapacitor1DESIGNOPPORTUNITIESTANTALUMWhyNotCeramics?CeramicCapacitorsIssues:•CapacitancedropsduetoincreasingDCBIAS•Capacitancedegradationovertemperaturerange•CapacitancegoesdownduetosmallACsignal(20-30%)•Loosingcapacitancedur

2、inglifetime•Piezoeffectmechanism•MechanicalweaknessDegradationofcapacitancecanleadtowrongperformanceandinstabilityofanamplifier2DESIGNOPPORTUNITIESTANTALUMSTABLEPARAMETERSWhyNotCeramics?CapacitancedependenttoBIASandtemperaturemaydegradesmoothingcapabi

3、lityTantalumTAJA10uF/6.3VCERAMICA10uF/6.3VX7R,X5RGraphofcapacitancestabilityGraphofcapacitancestability121211111010)9F9u8)87Fce(u76ce(65acitan54acitan4Cap332Cap21100102003040110200506032304017080450602Temperature(°C)905DCbiasvoltage70803410011076905DC

4、biasvoltage120(V)Temperature(°C)10011076120(V)3DESIGNOPPORTUNITIESTANTALUMTemperatureCharacteristicTypicalCapacitancevs.Temperature20%StableCapacitance+/-5%in15%10%temperaturerange–55/+85°C5%0%=StableFilteringevenwith-5%-10%OxiCapTMOperatingTemperatur

5、eCapacitance[%]-15%TantalumVariation-20%-50-250255075100125Temperature[°C]TypicalESRVersusTemperatureCap100%ESRdropwithTemperature80%OxiCap60%Tantalum-MnO2conductivitydriven40%20%astantalum0%-50-250255075100125-20%=BetterFilteringatHigherESRchange[%]-

6、40%-60%OperatingTemperaturesTemperature[°C]ESRcomparetoESR@25Cspecification42.Stablecapacitanceoverapplied2.StablecapacitanceoverappliedTANTALUMACsignalACsignalWhyNotCeramics?Degradationofcapacitancecanleadtowrongperformanceandinstabilityoftheamplifie

7、rTantalumTAJCERAMICA10uF/6.3VA10uF/6.3VX7R,X5RACsignalversuscapacitanceACsignalversuscapacitance10.64IN10.553.95)10.5)F3.9Fuu(10.45(e3.85enca10.4nca3.8ititc10.35c3.75papaa10.3aC3.7C10.253.6510.23.600.20.40.60.8100.20.40.60.81ACsignallevel(V)ACsignalle

8、vel(V)Measuredat5VapplicationvoltageThecapacitanceofceramiccapacitordropsdownwithappliedsmallACsignalvoltagethereforetheamplifiercannotsecurestableperformance5DESIGNOPPORTUNITIESTANTALUMWhyNotCeramics?CLEARFILTERINGBariumtitanateusedinceramicC