164.1 p channel deviceTwo reasons forreaders to bfamiliar with p channel devic> Existence in discrete-circuit>Moreimportant is theutilization of complementaryMOS or CMOS circuits.2025/11/27
2025/11/27 16 ⚫ Two reasons for readers to be familiar with p channel device 4.1 p channel device ➢ Existence in discrete-circuit. ➢ More important is the utilization of complementary MOS or CMOS circuits
174.1 p channel deviceStructureofpchanneldeviceThesubstrateisntypeandtheinversionlayerisptype.CarrierisholeThresholdvoltageisnegative.AllthevoltagesandcurrentsareoppositetotheonesofnchanneldevicePhysical operationis similartothatof nchanneldevice.2025/11/27
2025/11/27 17 ⚫ Structure of p channel device ➢ The substrate is n type and the inversion layer is p type. ➢ Carrier is hole. ➢ Threshold voltage is negative. ➢ All the voltages and currents are opposite to the ones of n channel device. ➢ Physical operation is similar to that of n channel device. 4.1 p channel device
184.1Complementary MOS or CMOSNMOSPMOSSGDDGsO.GateOCPolysiliconoxideSioSioThickSiO,(isolation)ptn4nnwellp-typebody> ThePMOS transistorisformed inn well> Anotherarrangement is also possible in which an n-type body is used andthe n device is formed in a p well.> CMOs is the most widely used of all the analog and digital IC circuits2025/11/27
2025/11/27 18 ➢ The PMOS transistor is formed in n well. ➢ Another arrangement is also possible in which an n-type body is used and the n device is formed in a p well. ➢ CMOS is the most widely used of all the analog and digital IC circuits. 4.1 Complementary MOS or CMOS
194.2Current-voltage characteristicsCircuitsymbolOutputcharacteristiccurvesChannel lengthmodulationCharacteristics ofpchanneldeviceBodyeffectTemperature effectsandBreakdownRegion2025/11/27
2025/11/27 19 ⚫ Circuit symbol ⚫ Output characteristic curves ⚫ Channel length modulation ⚫ Characteristics of p channel device ⚫ Body effect ⚫ Temperature effects and Breakdown Region 4.2 Current-voltage characteristics
204.2CircuitsymbolDDDQOOGOOBOBGOGO00SSs(a)(b)(c)(a)Circuit symbol for the n-channel enhancement-type MOSFET.(b)Modifiedcircuit symbol withan arrowheadonthe sourceterminal todistinguish it from the drain and to indicate device polarity (i.e., n channel)(c)Simplified circuit symbol to be used when the source is connected to thebody or when the effect of the body on device operation is unimportant.2025/11/27
2025/11/27 20 (a) Circuit symbol for the n-channel enhancement-type MOSFET. (b) Modified circuit symbol with an arrowhead on the source terminal to distinguish it from the drain and to indicate device polarity (i.e., n channel). (c) Simplified circuit symbol to be used when the source is connected to the body or when the effect of the body on device operation is unimportant. 4.2 Circuit symbol