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
無法做出二極體, 只能用寄生的
vertical PNP呢???

leo911759

其實也是有的。

有一些Paper就是用Diode，或是NPN。

" v" n1 l9 v, a) U8 F而會用PNP 是因為早期CMOS製程中，只能寄生等效PNP電路。

' }; ?7 L2 F/ i; B: O/ x其中的寄生等效Diode會有Latch-up的問題。

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:

1 G; t9 ]3 t! L( n8 J. g; g6 n- II believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for
( Z6 l7 B  ]2 u, D( |
/ P  S6 c9 r$ Xthe "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take
5 X  `* g" C4 N' p$ s7 \& ?4 C
- x9 D9 y% V# |$ o- {6 |0 R% D: Aon this:
5 n1 i. f7 a5 [7 T; D5 @% p4 `
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".

2- There usually is a specific structure for the "bipolar" that has characterization data available. When

0 m0 `% U9 S1 D$ i/ Jbuilding a bandgap structure, the good characterization is needed in order to properly determine the tempco of

: {0 r% v0 R+ H. p4 G% d! pthe Base-emitter voltage.
" }, |9 k1 a' d% ?
3- The additional structure of the bipolar should help prevent current injection into other substrate tied
/ s5 q, ?; u& f+ ^' q
devices.
: [  r. M/ f2 t1 l5 p


There 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……