Its are main the characteristic is there is layer of insulation of silicon of a 2 oxidations between metallic grid and raceway groove, because this has very tall input resistance (highest can amount to 1015Ω) . It also divides canal of N raceway groove and canal of P raceway groove, the symbol is shown 1 times like the graph.

 

 

It is normally underlay (substrate) with source pole S is received together. According to electric means different, MOSFET is divided again increase model, extinct model.

 

Alleged increase model it is to point to: When VGS=0 pipe is to show off-state, after adding correct VGS, majority carries stream child be attracted grid, thereby “ enhances ” of this area carry stream child, form electric raceway groove.

 

Extinct model it is to point to, form raceway groove namely when VGS=0, when adding correct VGS, can make majority carries stream child pour out of raceway groove, “ is consequently extinct ” carry stream child, make pipe changes direction end.

 

 

It is with N raceway groove exemple, it is two tall impure pH indicator are made on P silicon underlay the source diffuses area N+ and leakage diffuse area N+ , part again derivative source extremely S is mixed leakage pole D. Source pole and underlay interiorly connect, both always keeps equipotential.

 

The thereinbefore direction in graph 1(a) symbol is from extroversion report, express to expect from P profile (underlay) N pointing to a body raceway groove. When anode of fumble power source, source pole receives power source negative pole and make when VGS=0, raceway groove electric current (namely leakage pole electric current) ID=0. Lift gradually as VGS, suffer what grid positive electricity presses to attract, diffuse in two the minority that carries negaive electricity goes out to carry with respect to the induction between the area stream child, form from leakage extremely arrive the N of source pole raceway groove, the open voltage VTN(that is more than pipe when VGS is about commonly + when 2V) , canal of N raceway groove begins to guide, form ID of leakage pole electric current.

 

 

The typical product of MOSFET of homebred N raceway groove has above of 3DO1, 3DO2, 3DO4(to all be odd bar to be in charge of) , 4DO1(double bar is in charge of) . Their pin is arranged (bottom view) see a picture 2. Canal of MOS field effect compares “ fragile ” . Because its input resistor is very tall,this is, and bar – the capacitance between source pole very small, get outside electromagnetism field or electrostatic response extremely easily and electrified, and a few charge can be in extremely quite tall voltage is formed on capacitance (U=Q/C) , pipe attaint.

 

Accordingly each pin is wrung when the factory close together, or install inside tinsel, make G pole and S extremely show equipotential, prevent to accumulate electrostatic carry on one’s shoulder. Pipe need not when, overall lead also answer short receive. Should take care all the more when measure, adopt corresponding antistatic feeling measure.

 

The introduction detects below method:

 

1. intends the work

 

Before measuring, be opposite human body first after ground short circuit, ability feels the pin that touchs MOSFET. A lead and earth had better be received to connect on the artifice, make human body and earth keep equipotential. Part pin again, pull down next lead.

 

2. decides electrode

 

Dial avometer at R×100 archives, decide grid above all. If the resistor of some foot and other foot is infinity, proving this foot is grid G. Exchange expresses a pen to be measured again, the resistance between S-D should come thousands of Europe for hundreds of Europe, among them block value is lesser that time, black list pen receives it is D pole, what red watch pen receives is S pole. Japanese made 3SK series product, s pole and envelope put through, decide S pole very easily accordingly.

 

 

Ability of 3. examination enlarge (cross guide)

 

G extremely impending, black list pen receives D pole, red watch pen receives S pole, feel G pole with finger next, watch needle is due bigger deflexion. Canal of effect of field of double bar MOS has two grid G1, G2. To distinguish, usable hand feels G1, G2 pole respectively, express range of deflexion of side of needle towards the left among them bigger it is G2 pole.

 

At present some MOSFET canals are between G-S pole increased to protect diode, do not need an each pin short circuit at ordinary times.