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？

hoodlum

小弟的看法是
會不會是標準CMOS的製程裡
  r+ U" M, B. E% Z; n. f+ L- _無法做出二極體, 只能用寄生的
) l2 q! m$ V/ ]5 bvertical PNP呢???

leo911759

其實也是有的。
" P* A  c2 ?: }9 o
有一些Paper就是用Diode，或是NPN。

而會用PNP 是因為早期CMOS製程中，只能寄生等效PNP電路。
9 u3 f2 `+ Y- x
% z  h8 A7 h; X其中的寄生等效Diode會有Latch-up的問題。
- [5 J# ~1 W! Z+ w7 ]+ P
這是製程受限的關係，比較先進的製程就沒這種問題了。

patrick02046

在EDA Board 抓的資訊， 參考一下:
% S7 w; }( F) ]" b4 v; H
/ A" ]9 ~5 t6 N1 x/ zI believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for
' T* d0 V$ v# R
! O! j- W- Q: M9 F% p- cthe "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take
8 h- u  X; A# X3 J  ?; r
on this:

8 Q/ S" X' x8 {+ ]1- 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 d. Y: a4 U: d! O1 W
2- There usually is a specific structure for the "bipolar" that has characterization data available. When
, p0 f) L6 u) T
building a bandgap structure, the good characterization is needed in order to properly determine the tempco of

- T; O6 V* N6 r- h; ~: Xthe Base-emitter voltage.
* Y! \. N/ p8 [. k$ Q
0 a& b7 p1 U% G- Q5 S! l3- The additional structure of the bipolar should help prevent current injection into other substrate tied

devices.
+ f! M* S) @+ U' w3 T
5 \' n4 Z$ |' y# j  J. K

6 Z. G) e% ]* \2 mThere is, of course, nothing preventing the use of a P+/Nwell diode in your application.

luckyhuihui666

主要原因就是二极管不准确……