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
2 Z0 Y/ b- I& N. c! C( M0 b會不會是標準CMOS的製程裡
3 }: u: k4 B: d7 f無法做出二極體, 只能用寄生的
vertical PNP呢???

leo911759

其實也是有的。

1 l$ L8 h: i+ W* 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。

* t0 q; K. d# g) O其中的寄生等效Diode會有Latch-up的問題。

" G& h# V+ g5 b8 a0 b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:

I believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for

6 D3 e7 B! N, }$ G+ R" ^, W0 [the "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take

- d. K8 G; O7 V+ Aon this:

1- The "bipolar" will simulate more accurately than the "diode", since it will include the substrate current

4 d- V7 S; C/ {' m  S3 jthat is probably not modeled for the "diode".
$ H9 S/ g  `& O1 [. x
/ L8 e  }5 N: z; x! p) [2- There usually is a specific structure for the "bipolar" that has characterization data available. When
2 C' e, i: {* p1 P
building a bandgap structure, the good characterization is needed in order to properly determine the tempco of
8 R; C. q$ \5 e/ x8 P( a
( B" {/ }1 J/ ?# pthe Base-emitter voltage.
; Y$ c+ C4 b1 y; q
3- The additional structure of the bipolar should help prevent current injection into other substrate tied

# J* M6 `! s: b7 `devices.
6 o( ~: L% Z1 v1 H3 v7 S$ s+ d& f


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……