CMOS工艺下bandgap 负温度系数器件，为什么使用PNP管而不是用二极管？

scy8080

CMOS工艺下bandgap 负温度系数器件，为什么使用PNP管而不是用二极管？

luckyhuihui666

主要原因就是二极管不准确……

patrick02046

在EDA Board 抓的資訊， 參考一下:
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: W, T9 V$ e) S7 II believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for

the "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take

6 Q+ _; M! z6 F; zon this:
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5 a$ S. G- |0 ^7 v, L) p1- The "bipolar" will simulate more accurately than the "diode", since it will include the substrate current

that is probably not modeled for the "diode".
5 }& o  c2 _: e  u0 m2 \
" w8 R  ?5 M: e! N2- There usually is a specific structure for the "bipolar" that has characterization data available. When
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3 |7 w* X( m" g5 h( D4 fbuilding a bandgap structure, the good characterization is needed in order to properly determine the tempco of

  R/ e, `$ h& D3 ^( y( ?5 h* tthe Base-emitter voltage.

  @& c# f1 f' q$ ]9 ^' R: D$ `3- The additional structure of the bipolar should help prevent current injection into other substrate tied

devices.
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* Y$ ]3 ^3 {2 B% VThere is, of course, nothing preventing the use of a P+/Nwell diode in your application.

leo911759

其實也是有的。
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有一些Paper就是用Diode，或是NPN。
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6 X6 B1 F7 q7 }  p; b; D0 u而會用PNP 是因為早期CMOS製程中，只能寄生等效PNP電路。

9 c9 x0 w, i0 S其中的寄生等效Diode會有Latch-up的問題。

! _, s+ S" v0 Y- {$ P  u7 P+ o這是製程受限的關係，比較先進的製程就沒這種問題了。

hoodlum

小弟的看法是
會不會是標準CMOS的製程裡
* Z# J5 e* U+ ]7 p6 ~5 r: r無法做出二極體, 只能用寄生的
vertical PNP呢???