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[問題求助] 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?

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發表於 2012-2-3 14:59:08 | 顯示全部樓層 |閱讀模式
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?
發表於 2012-2-3 22:59:40 | 顯示全部樓層
小弟的看法是- W; o6 R1 @! l/ N) P# v) z0 y! ^
會不會是標準CMOS的製程裡
. ^, n& y8 e) y3 T5 {, U) X* R% B9 g" R無法做出二極體, 只能用寄生的# R6 X$ L/ t7 @% d) @. g$ ]3 M+ \
vertical PNP呢???
發表於 2012-2-8 16:02:57 | 顯示全部樓層
其實也是有的。7 |- H" d7 o6 Z0 }3 Y. e' H
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有一些Paper就是用Diode,或是NPN。8 t3 |! _+ Y* |' l. P2 I4 {9 U0 B

. B' L* U+ m7 w0 ^而會用PNP 是因為早期CMOS製程中,只能寄生等效PNP電路。! z. l% ?; b4 x. u+ B. M6 `$ D
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其中的寄生等效Diode會有Latch-up的問題。
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- G7 H$ h, M* k( n9 |這是製程受限的關係,比較先進的製程就沒這種問題了。
發表於 2012-2-9 13:24:53 | 顯示全部樓層
在EDA Board 抓的資訊, 參考一下:
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I believe that what you are getting at is that there is a specific structure of P+/Nwell/Psub that is used for . v9 p; F$ U* E4 W
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the "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take 5 l) z$ D+ Z: w+ L9 J2 w1 V+ t

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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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that is probably not modeled for the "diode".
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2- There usually is a specific structure for the "bipolar" that has characterization data available. When 0 n) c7 q- W2 s+ E* I
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building a bandgap structure, the good characterization is needed in order to properly determine the tempco of . B, b/ d$ E0 [! @2 F9 W3 ?% _

  _8 l' z. f' C$ _the Base-emitter voltage.
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' |1 f0 @4 \0 o0 a/ O3- The additional structure of the bipolar should help prevent current injection into other substrate tied   L. E# ~* L! D; _
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devices.
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( t+ E2 H1 ]: [: {There is, of course, nothing preventing the use of a P+/Nwell diode in your application.
發表於 2012-4-13 20:06:38 | 顯示全部樓層
主要原因就是二极管不准确……
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