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在EDA Board 抓的資訊, 參考一下:3 m J# D' q$ R+ w/ Q
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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
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; f6 s# ^, q7 O0 C9 [+ fthe "bipolar", so you are asking why use that structure rather than simply a P+/Nwell "diode". Here is my take
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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
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building a bandgap structure, the good characterization is needed in order to properly determine the tempco of ! L) j% N! x8 I" \2 Q+ I5 a2 I! F
* R$ `( d( D5 p+ r- p* O, tthe Base-emitter voltage.
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3- The additional structure of the bipolar should help prevent current injection into other substrate tied 6 Q7 u9 L; B) `
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There is, of course, nothing preventing the use of a P+/Nwell diode in your application. |
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