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jc2
Joined: 05 Mar 2005
Posts: 70
Helped: 2
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 30 Mar 2007 4:44 Geometry effect |
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What is the Geometry effect?, and
How does the Geometry effect affect the treshold voltage?
thanks
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nikhilele
Joined: 11 Jan 2006
Posts: 535
Helped: 20
Location: Bangalore India
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| 30 Mar 2007 6:08 Geometry effect |
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| Can you tell in detail, which device you are talking about
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jc2
Joined: 05 Mar 2005
Posts: 70
Helped: 2
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| 01 Apr 2007 0:13 Re: Geometry effect |
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I found it in this sentence:
...the W and L of MS1 are the same as those of M1–M3 to eliminate
the variation on the threshold voltage due to the geometry effect.
thanks
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elbadry
Joined: 06 May 2005
Posts: 358
Helped: 62
Location: Egypt
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| 01 Apr 2007 15:02 Re: Geometry effect |
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Generally, the Vth of the transistor depends on its dimension ( the dimensions will determine the charge distribution and hence the Vth ).
A number of effects can cause Vth variations due to dimensions such as ( short channel effect, reverse shor channel effect, narrow width effect, reverse narrow width effect, LOD effect...etc )
As a rule of thumb, for better matching, you have to use fingued transistors with constant finger W and L. In more modern technologies you may even need to use transitor multipliers and avoid fingers altogether
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leohart
Joined: 10 Nov 2006
Posts: 229
Helped: 12
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| 02 Apr 2007 15:30 Re: Geometry effect |
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| elbadry wrote: |
Generally, the Vth of the transistor depends on its dimension ( the dimensions will determine the charge distribution and hence the Vth ).
A number of effects can cause Vth variations due to dimensions such as ( short channel effect, reverse shor channel effect, narrow width effect, reverse narrow width effect, LOD effect...etc )
As a rule of thumb, for better matching, you have to use fingued transistors with constant finger W and L. In more modern technologies you may even need to use transitor multipliers and avoid fingers altogether |
hi,elbadry,what is a transistor multiplier?Can it provide better matching than multifingers transistor?
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elbadry
Joined: 06 May 2005
Posts: 358
Helped: 62
Location: Egypt
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| 04 Apr 2007 0:06 Re: Geometry effect |
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| A multiplier is simply another complete transistor ( separate gate , source and drain ). In modern technologies it's better to use multipliers due to whatis known as LOD effect
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Brittoo
Joined: 24 Jan 2007
Posts: 70
Helped: 11
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| 12 Apr 2007 12:27 Re: Geometry effect |
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Hi all
What is LOD effect?? could you plz elaborate on this??
Regards
Brittoo
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