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:

4 e7 l# n) [8 W; P6 c; `7 B5 yI believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for
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  l. O" ]* X% z9 {: w2 lthe "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take
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4 a; x1 C4 ?, ]  k. b6 ^on this:
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1- The "bipolar" will simulate more accurately than the "diode", since it will include the substrate current
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$ I1 L7 o* `4 M; M% p, w3 w4 x5 Ithat is probably not modeled for the "diode".

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

) n3 T  \, c/ w4 Nbuilding a bandgap structure, the good characterization is needed in order to properly determine the tempco of
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the Base-emitter voltage.

3- The additional structure of the bipolar should help prevent current injection into other substrate tied

devices.

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( F" i/ F- }3 S) d: qThere 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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3 y6 M& t$ Z6 a8 @有一些Paper就是用Diode，或是NPN。
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而會用PNP 是因為早期CMOS製程中，只能寄生等效PNP電路。

其中的寄生等效Diode會有Latch-up的問題。

4 M8 }+ Q- w* b/ Q/ z" q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
1 i" _+ y4 L" i% b" M無法做出二極體, 只能用寄生的
7 S* k: D( ^: t$ |/ bvertical PNP呢???