5 t8 m$ j* Y2 L2 u1 b+ U5 o& SI believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for 4 M1 h6 @$ s1 l0 z( F: O1 [: ^
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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 8 B' r& p- F. ~2 D" T3 }2 `* M1 W s9 P* H' C
on this:7 Y. V6 P2 h |. J7 g Q4 C! v
! P8 h8 l# f# o% M! s H3 y/ Y" _1- The "bipolar" will simulate more accurately than the "diode", since it will include the substrate current 0 V2 W* G- v. p) H r0 c2 b! j2 w
6 O+ B* D. i5 i7 q7 wthat is probably not modeled for the "diode".( X2 `9 o6 A' g$ W+ }
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2- There usually is a specific structure for the "bipolar" that has characterization data available. When ' i* C0 K5 c! @- r" R/ {
6 F4 T' @: u m; m0 a: Tbuilding a bandgap structure, the good characterization is needed in order to properly determine the tempco of * e& |8 s4 a/ [$ X: Y" e0 J$ m1 {: B( C
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the Base-emitter voltage.9 L- j5 f1 e; b5 I
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3- The additional structure of the bipolar should help prevent current injection into other substrate tied 7 `& T' Q" M( v; Y. G
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: X8 W+ v. f# B2 R7 [) p0 f$ i9 P6 FThere 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……