! ~6 E; O4 N9 ^& [/ ?1 K有一些Paper就是用Diode，或是NPN。 t0 F& i; b: |2 I5 x+ {1 r s% c0 S9 b' v0 p, E
而會用PNP 是因為早期CMOS製程中，只能寄生等效PNP電路。' u% z) Y+ R! |' O# P. ^
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其中的寄生等效Diode會有Latch-up的問題。. T2 R5 X& l$ R: N4 c0 v
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這是製程受限的關係，比較先進的製程就沒這種問題了。作者: patrick02046 時間: 2012-2-9 01:24 PM
在EDA Board 抓的資訊， 參考一下:3 z9 V% ]2 s/ P. v$ a
. T- R! h/ W# [- b2 b% F& aI believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for . M0 }2 O/ A$ y) {/ j ) x) k8 V# z0 r$ ^the "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take 2 T" Y9 V+ k4 d' N, Y7 t3 ^8 d" K- f- r
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0 v# A; x2 C- A; m1- The "bipolar" will simulate more accurately than the "diode", since it will include the substrate current - Q' E7 U/ l6 k* j5 U" f: M- Z g
4 ^9 A: d% e# xthat is probably not modeled for the "diode".! C. w+ O' F; f6 X% F+ @
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2- There usually is a specific structure for the "bipolar" that has characterization data available. When . v; J1 w9 q, a4 \* z: z8 J
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building a bandgap structure, the good characterization is needed in order to properly determine the tempco of 9 G. {- y( k( {1 x3 [
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the Base-emitter voltage., I- a9 v0 Z8 V U8 ]
3 X# c; O# D. u8 e$ A e8 V9 G3 n7 A3- The additional structure of the bipolar should help prevent current injection into other substrate tied ) J% G( c( p6 H4 l0 I : [6 l! |% K Z; h8 i: }devices. 0 p v/ v+ i8 V7 p3 n3 i9 v9 t+ r, w2 k _# o
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There is, of course, nothing preventing the use of a P+/Nwell diode in your application.作者: luckyhuihui666 時間: 2012-4-13 08:06 PM
主要原因就是二极管不准确……