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Field effect is in charge of
From;  Author:Stand originally
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Field effect is in charge of
More and more electron circuit are using an effect to be in charge of now, be in especially acoustics domain is more such, field effect canal and transistor are different, it is parts of an apparatus of control of a kind of voltage (transistor is) of voltaic control parts of an apparatus, its are characteristic more elephantine valve, it has very tall input impedance, bigger power gain, because be voltage control parts of an apparatus noise is so little, its structure diagram is like graph C-a.
Field effect canal is a kind of sheet pole transistor, it has tie of a P-N only, below the condition of 0 bias voltage, it is to guide connect, if be in its grid (G) and source extremely (a retrorse bias voltage is added between S) (call grid bias voltage) P-N thickening falls in action of retrorse electric field (weigh extinct area) raceway groove narrow, its leak extremely voltaic general decrescent, (Be like graph C1-b) , when it is certain that retrorse bias voltage is achieved, extinct area places " of complete raceway groove " , right now, field effect canal enters off-state to be like graph C-c, we weigh right now retrorse bias voltage break tension for clip, express with Vpo, vpo=Vps can is with expressing nearly between it and grid voltage Vgs and Vds of leakage source voltage | Vgs | , here | Vgs | It is the absolute value of Vgs.
When production field effect is in charge of, before if be in,grid material is joined, impose the sentence of a very thin insulation layer first on raceway groove, will reduce grid electric current greatly, big also earth increases his to input impedance, as a result of the existence of layer of predestined relationship of this a special skill, field effect canal can work in slant buy condition, we call canal of effect of this kind of field canal of effect of insulation bar field, call MOS field effect the canal again, so field effect canal has two kinds of kinds, one kind is canal of effect of insulation bar field, it can work in slant reversely buy, 0 slant buy and to slant buy condition, one kind is canal of knot bar effect, it can work only in slant reversely buy condition.
Canal of effect of insulation bar field is divided again to increase model and extinct model two kinds, we weigh those who connect to guide below normal circumstance for extinct model field effect canal, say to increase in what disconnect below normal circumstance model effect canal. Increase model field effect is in charge of a characteristic: The Id(when 盫 Gs=0 leaks extremely electric current) =0, just begin to guide when Vgs increases certain to be worth only, leakage pole electric current arises. Say to begin to appear the Vgs of bar source voltage when leakage pole electric current is open voltage.
Extinct model the characteristic that field effect is in charge of, it can be in or negative bar source voltage (or negative bias) next jobs, and on grid flow basically without bar (very tall input resistor) .
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