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MOS Cap region of operation (Read 3393 times)

AnalogDE Senior Member Offline Posts: 137	MOS Cap region of operation Jul 14^th, 2008, 10:50pm MOS Caps can either be operated in accumulation or inversion... What are the pros/cons of each?
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neoflash Community Fellow Offline Mixed-Signal Designer Posts: 397	Re: MOS Cap region of operation Reply #1 - Aug 16^th, 2008, 9:48pm MOSCAP in inversion region is more stable with frequency and is lower in loss. Accumulation region capacitance will reduce with higher frequency. Also the loss is higher.
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vivkr

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Re: MOS Cap region of operation
Reply #2 - Aug 17^th, 2008, 10:58pm

neoflash wrote on Aug 16^th, 2008, 9:48pm:

MOSCAP in inversion region is more stable with frequency and is lower in loss.

Accumulation region capacitance will reduce with higher frequency. Also the loss is higher.

Hi neoflash,

I would have imagined the reverse to be true. Atleast the textbook model shows you 2 curves for the inversion region, the high-f and low-f ones, whereas for accumulation, this is not the case. Are you considering the losses due to the parasitic resistance etc. that come into play with the accumulation cap (which the textbook does not consider)?

Regards,
Vivek

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nano_RF

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madison

Re: MOS Cap region of operation
Reply #3 - Aug 20^th, 2008, 8:18am

Hi,

I am also of the opinion that in accumulation MOS cap is more stable then inversion mode.

About the loss not sure but I guess the bottom layer is a p-type (hole) conduction in accumulation as compared to an electron conducive (NMOS Cap assumed) with electron reservoir (n+ regions) in inversion mode. So it could be lossy but still not positive though.

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