PMOS refers to an n-type substrate, p-channel MOS transistor that carries current by the flow of holes.Full name: positive channel Metal Oxide Semiconductor;Alias: positive MOS.
Chinese name
MOS tube
Foreign name
pmos
Alias
positive MOS
Chemicals
Mesoporous silica based organic-inorganicHybridizationMaterial Science
PMOS refers to an n-type substrate, p-channel, MOS transistor that carries current by the flow of holes
Full name: positive channel Metal Oxide Semiconductor
Alias: positive MOS
metallic oxideSemiconductor field effect (MOS) transistors can be divided into N-channel and P-channel. P-channel silicon MOS field effect transistors have two P+regions on N-type silicon substrate, called source andDrain electrodeWhen there is no conduction between the two electrodes and sufficient positive voltage is applied to the source electrode (the grid is grounded), the N-type silicon surface under the grid is P-typeInversion layerAnd become the channel connecting the source and drain.Changing the grid voltage can change theHole densityTo change the resistance of the channel.This MOS field-effect transistor is called P-channelEnhanced field effect transistor。If there is no gate voltage on the surface of N-type silicon substrate, P-type inversion layer channel already exists. With proper bias voltage, the resistance of the channel can be increased or decreased.Such MOS FETs are called P-channel depletion FETs.They are collectively referred to as PMOS transistors.
The hole mobility of P-channel MOS transistor is low, so the hole mobilityworking voltage When the absolute values are equal, the transconductance of PMOS transistor is less than that of N-channel MOS transistor.In addition, P-channel MOSTransistor threshold voltageThe absolute value of is generally high, requiring a higher working voltage.The voltage and polarity of its power supplyBipolar transistor——The transistor logic circuit is not compatible.PMOS operates at a lower speed due to its large logic swing, long charging and discharging process, and small transconductanceNMOS circuit(See N-channel metal oxide semiconductor integrated circuits), most of which have been replaced by NMOS circuits.Just becausePMOS circuitThe process is simple and the price is cheap. Some medium - and small-scale digital control circuits still use PMOS circuit technology.
MOSFET has three legs, generally G, D and S, and the conduction and cut-off between D and S can be changed by adding control signals between G and S.PMOS and NMOS are completely similar in structure, but the difference is the doping type of the substrate and source drain.In brief, NMOS is the N-type doped region formed by selective doping on the P-type silicon substrate as the source and drain region of NMOS;PMOS is a P-type doped region formed by selective doping on the N-type silicon substrate as the source and drain region of PMOS.The distance between the two source drain doped regions is called the channel length L, and the effective source drain region size perpendicular to the channel length is called the channel width W.For this simple structure, the source and drain of the device are completely symmetrical, and the specific source and drain can be finally confirmed only according to the flow direction of the source and drain current in the application.
The working principle of PMOS is similar to that of NMOS.Because PMOS is N-type silicon substrate, most of themcarrierIt is an electron, a few carriers are holes, and the source and drain regions are P-type doped. Therefore, the operating condition of PMOS is to apply on the gate relative to the sourceNegative voltageThat is, negative charged electrons are applied to the gate of PMOS, while movable positive charged holes and depletion layers with fixed positive charges are induced on the substrate. Regardless of the influence of the charges in silicon dioxide, the number of positive charges induced in the substrate is equal to the number of negative charges on the PMOS gate.When the strong inversion is reached, the positive charge holes at the source end reach the drain end through the conduction P-type channel under the effect of the drain source voltage that is negative relative to the source end, forming a source from source to drainLeakage current。Similarly, the more negative VGS (the greater the absolute value), theOn resistanceThe smaller the current, the greater the value.
Like NMOS, the working area of the conducting PMOS is also divided into unsaturated area, critical areaSaturation pointAnd saturation zone.Of course, both NMOS and PMOS are in the cut-off region when no inverted channel is formed, and the voltage conditions are:
VGS
|VGS|>|VTP (PMOS)|，
It is worth noting that the VGS and VTP of PMOS are both negative.
PMOS integrated circuit is a device suitable for low speed and low frequency applications.PMOS integrated circuit is powered by - 24V voltage.
MOS field-effect transistor has high input impedance, which is convenient for direct coupling in the circuit and easy to make large-scale integrated circuits[1]。
Comparison of characteristics of various field effect transistors
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At the International Electronic Devices Conference (IEDM) in December 2004, it was stated that the double stress pad (DSL) method led to an increase of 15% and 32% of the effective driving current in NMOS and PMOS, and an increase of 11% and 20% of the saturated driving current, respectively.The hole mobility of PMOS can be increased by 60% without using SiGe, which has become the focus of other strained silicon research.
Chemicals
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PMOs are periodic mesoporous organicsHybridizationMaterial Science.It is a kind of organic and inorganic components at the molecular levelHole wallMedium hybrid materials, which have many unique properties: organic functional groups are evenly distributed in the pore walls and do not block the pores, which is conducive to the introduction and diffusion of guest molecules;The organic functional groups in the skeleton can adjust the physical and chemical properties of the material to a certain extent, such as mechanical properties, hydrophilic/hydrophobic properties;It can realize the adjustment of the channel and hole wall functionality at the same time. Because of this, PMOs have become a research hotspot in the field of materials science.
The order represented by M41S (Mobile composite of material) and FSM (folded sheets mesoporous material al) in the early 1990sMesoporeThe report of silicon oxide materials set off an upsurge of research on the synthesis and application of mesoporous materials.one side,Ordered mesoporous materialsThe emergence ofapertureLimitations can be applied to organic macromoleculesBiomacromoleculeIt has been applied in the fields of solid support, catalytic conversion, etc;On the other hand, pores with different orientations, sizes and connectivity in mesoporous materials can be used as ideal nanoreactors for assembly and confinementMetal complexAnd biological macromolecules, directional synthesisNanoparticlesEtc. of original mesoporous materialsHole wallThe composition is silicon oxide. In order to expand its application in different fields, researchers are committed to expanding their research on pore wall composition, including heteroatom doped mesoporous silicon oxide, mesoporous metal oxides, metals, sulfides, carbon, polymers, etc,Organic modification of mesoporous silica is one of the most convenient and flexible ways to expand its application.Organic functionalized mesoporous silica materials are mainly divided into surface bonded andBridge keyType organic inorganicMesoporeThere are two kinds of materials.Surface bound organic-inorganic mesoporous materials can be grafted or polycondensated organicallyGroupIntroduced into the pores of mesoporous materials.The introduced organic groups can also derive newactive center。The active sites of surface bound organic-inorganic mesoporous materials are relatively easy to approach, and there are relatively many kinds of organic groups available.However, the materials synthesized by this method have uneven distribution of organic groups, and the occupied pore space is reducedPore volumeAnd so on.Bridged organic-inorganic mesoporous materials, PMOs (Periodic Mesoporous Organosilicas) for short, refer to theHole wallOrganic inorganic mesoporous materials in structure[2]。
Secure Operating System
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PMOS dedicated mobile operating system based on YunOS deep customization.
Application of PLC in reverse protection circuit
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PMOS is used in the reverse protection circuit. Without the use of diodes, the voltage drop is smaller and the dissipation of reactive power is less.Although there is a parasitic forward diode, it is completely useless.When the circuit is powered on normally, the GATE is connected to the 0 potential far below the D terminal, and the PMOS is fully on.When the power supply is reversed, the potential of GATE is much higher than that of S terminal, and PMOS is completely cut off[3]。
