% P. Q) B6 ^) e! m/ E- o其中的寄生等效Diode會有Latch-up的問題。 % b; D% O, T7 _3 n, W/ c; F, T5 o/ F* A# d6 d4 B9 {- d
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:1 y% I- N6 f& j5 e
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I believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for ( M8 \5 q$ \ r
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the "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take " l2 D& Q6 J- D$ w; a9 N. |/ ~ ' `/ a0 t2 l9 q# o; |: I! gon this: # G; y5 A- F) A& L8 U# S! {# I7 d3 ^
1- The "bipolar" will simulate more accurately than the "diode", since it will include the substrate current % ?: D2 n( Z6 d- f- @8 O
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that is probably not modeled for the "diode". ( }# v/ e! K) x ! V: d; r) E5 p" h8 f8 n) V2- There usually is a specific structure for the "bipolar" that has characterization data available. When / I- h5 A% a& ?1 @* B: s 9 y6 s4 C. z5 z- _$ ?building a bandgap structure, the good characterization is needed in order to properly determine the tempco of 4 x4 G4 s9 ]5 [
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the Base-emitter voltage. 9 {7 O6 v% |! Z Y7 Q7 z. p1 P/ l% n8 a) \7 X0 E0 U
3- The additional structure of the bipolar should help prevent current injection into other substrate tied 9 P A( W- Q& o3 H) m% }1 s5 x! ]: X6 x
devices. 5 P0 T P9 h/ ?8 [3 f6 k: }/ X) P, Q9 a) v
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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……