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
" `, {7 O4 f, L. a' c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。

0 X" A/ \: \0 A& C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 G9 S: i% y: O( W2 A
其中的寄生等效Diode會有Latch-up的問題。
& G! m4 z% L& ~8 q' A) M2 W
6 U3 C5 q7 ?. |0 U6 ]6 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:
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# J" V; S6 W, X& e. w4 J7 SI believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for

, \* C2 N3 H, jthe "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take

  G% I% X2 C5 F! R) |/ pon this:
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1- The "bipolar" will simulate more accurately than the "diode", since it will include the substrate current
, L2 A1 d/ R3 _$ w
! R+ n) z  ]( N  G  k8 j2 I! b# p" Zthat is probably not modeled for the "diode".

3 |9 A: X9 G4 R2 ?2- There usually is a specific structure for the "bipolar" that has characterization data available. When

: P9 d5 h  _! d" q3 Pbuilding a bandgap structure, the good characterization is needed in order to properly determine the tempco of
, ]1 ?: k. z  \" e
' j& v' u& N% P9 R8 Gthe Base-emitter voltage.

' u7 I3 J/ F/ k  q3- The additional structure of the bipolar should help prevent current injection into other substrate tied

devices.

2 @, ^5 J8 X+ g0 W/ X

  Z( W; L- _% Z. Z. LThere 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……