) a- p: e% M/ v0 L; g R# v$ s有一些Paper就是用Diode，或是NPN。 ! m$ A/ a2 P0 A" ]+ j/ ]- w9 R" y- N7 U8 ~
而會用PNP 是因為早期CMOS製程中，只能寄生等效PNP電路。 1 C+ _; v) X1 W: S8 w" y* Y9 P1 `4 N) }$ c$ b& ?3 ^, M0 f
其中的寄生等效Diode會有Latch-up的問題。 6 \- D. c* ?4 n- V9 M0 E! a6 o6 w2 X1 K5 Y% n( v
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 ~$ q( j9 R: B, t' o! u/ T. v) t* Q' a( a( }- C
I believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for 2 Y3 R" e% t/ k, w* B! E4 ]
) M. S" F% Q$ v0 Z- E
the "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take 7 p) l6 b2 v' f" H `3 A0 ~% {! M9 [0 I) |# ~( Q2 s
on this:" D1 G) l& _" M5 F% i' C. Q
' T9 g7 ]. [3 s; h* f* _- Q6 U7 Q1- The "bipolar" will simulate more accurately than the "diode", since it will include the substrate current 7 J; W" P& o- j( x8 W6 z. j* a& r5 ?8 u, z* O" }6 K
that is probably not modeled for the "diode".8 c2 X+ k9 F( g6 P
* P- e* n( B, F6 \& {
2- There usually is a specific structure for the "bipolar" that has characterization data available. When 5 b" X7 o$ y4 J3 O j' ]' ~ 1 @& Y4 d" f8 Jbuilding a bandgap structure, the good characterization is needed in order to properly determine the tempco of * T9 z" B$ w9 j; z% d7 t4 T1 u
% c/ [& y4 S0 Z8 V. U, D( y
the Base-emitter voltage. 8 a# D& p. a# P8 K) y( V0 s1 p$ e% d2 t5 D) V! n8 w- ]. R8 r
3- The additional structure of the bipolar should help prevent current injection into other substrate tied 0 h& y( [0 [- `( Y$ @3 [6 b ' R# ]" C4 U0 G& j4 M$ F% Wdevices.; A* P3 f, A7 |* p, `
- s& G2 v0 h' ~# C3 C4 r! u0 ^
- L& `! v8 G. e, b0 t: Q 9 a/ Z9 z8 d& dThere 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……