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penchal_gv
Joined: 04 Feb 2006
Posts: 20
Helped: 1
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 13 Apr 2007 6:54 making resistor |
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Hi All,
why we make always resistor with poly,nwell.......but not with active even though active(P+/N+) having more resistance than poly and well. plz clarify me
Thanks
Penchal
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leohart
Joined: 10 Nov 2006
Posts: 229
Helped: 12
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| 13 Apr 2007 12:06 making resistor |
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| active should always been made as low sheet resistor as possible,because they will affect the parasitic s,d resistance.You can use it as a resistor if u like,but this kind of resistor and nwell resistor is not so precise as poly.
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siskam
Joined: 13 Apr 2007
Posts: 2
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| 13 Apr 2007 12:16 Re: making resistor |
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| penchal_gv wrote: |
Hi All,
why we make always resistor with poly,nwell.......but not with active even though active(P+/N+) having more resistance than poly and well. plz clarify me
Thanks
Penchal |
In integrated circuit (e.g. such as procesor) there are active resistors for pull-down (or pull-down).
Inside out, in "active load" (for testing el. equipment) are used FET as a electronic resistor.
Martin
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n1cm0c
Joined: 05 Sep 2006
Posts: 183
Helped: 25
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| 13 Apr 2007 14:44 Re: making resistor |
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active is always covered with silicide, to reduce the resistance of the source/drain.
You can ask for a silicide block mask that will allow you to have "native" active, this is very common in esd protection devices.
The resistance value can be relatively well controlled, but the parasitic capacitance is a problem. It's also non-linear, so you'll have distortion. The resistance itself is actually rather like a JFET.
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