1 J5 d3 n+ a# o6 a, V- ^I believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for " \( Z; P& t4 H# l0 F8 t* {8 n3 p
; p! ]; ^" R2 f- {+ xthe "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take n1 j; @. [' Z8 y0 l
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: V, p, G0 W f! ^# X/ v1- The "bipolar" will simulate more accurately than the "diode", since it will include the substrate current - h4 B7 j2 ?% `' j1 a
: L% o4 O, Q* [that is probably not modeled for the "diode". " {. V1 r; L. {* U4 [ % c( u3 x2 W7 f/ Y2- There usually is a specific structure for the "bipolar" that has characterization data available. When 8 @% \* O7 R! J% W/ w 3 ]! c. f0 i7 b7 g, w! R6 ~6 P! Wbuilding a bandgap structure, the good characterization is needed in order to properly determine the tempco of 4 s' m1 n# U1 d& i 0 @7 i: S/ ^6 E$ n$ S( F8 c6 Lthe Base-emitter voltage. # E( G3 F1 D* [6 t' j 6 [+ u) ]5 n ?8 c3- The additional structure of the bipolar should help prevent current injection into other substrate tied 0 g A2 F* y4 ~0 _) p. }; F$ A + @" M' t) N8 D3 t- V6 k9 Ndevices.% S! D7 c: ^- Q: N
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6 U7 I# c3 s+ g - c5 A* r2 O, R5 U3 X i; b5 L6 K; tThere 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……