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MOSCAP (Read 1630 times)

raja.cedt Senior Fellow Offline Posts: 1516 Germany	MOSCAP Jul 08^th, 2009, 4:12am hi, can any body please tell me why moscap is made in N substrate (i knew that we can connect nmos drain and source and it works well, in that case it will be P substrate) Thanks, rajasekhar.N
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solidstate Junior Member Offline Posts: 16 Munich, Germany	Re: MOSCAP Reply #1 - Jul 8^th, 2009, 2:19pm As far as I know, this allows for the moscap to have a dedicated ground terminal; without the nwell, the bottom plate of the moscap would be the substrate, so substrate noise (e.g. from digital logic) could then be coupled in..
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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: MOSCAP Reply #2 - Jul 8^th, 2009, 9:46pm hi, thats fine but they could have put pwell right because then it works like nmos then we can connect Drain and Source.. Thanks, rajasekhar.
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shashi.kiran New Member Offline Posts: 5 india	Re: MOSCAP Reply #3 - Jul 9^th, 2009, 4:39am if ur using NMOS -CAP it has to be p-sub and PMOS CAP it has to be n-well ..!!..i dont think we use Nmos and n-type substrate ..!!
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Dipankar Community Member Offline Posts: 59	Re: MOSCAP Reply #4 - Jul 9^th, 2009, 7:01am Dear All, N-Moscap in nwell means you need very low gate voltage to send the device into strong inversion. So the C-V does not have accumulation region . With this kind of C-V (monotonic) a VARACTOR is realized. They call it NMOSCAP-VARACTOR.
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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: MOSCAP Reply #5 - Jul 9^th, 2009, 9:24am hi, i donno weather i am complicating this question or not, but what i thought is it is like having n diffusion's in nwell,so how inversion will come..i think it will be in accumulation only and works for +ve voltage Thanks, Rajasekhar.
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shashi.kiran New Member Offline Posts: 5 india	Re: MOSCAP Reply #6 - Jul 9^th, 2009, 9:40pm @ raja if you apply +ve gate voltage ...how can u say its in accumulation ??...infact it will be inverted ....i guess dipankar got it right ...it should be in inversion with less gate voltage.
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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: MOSCAP Reply #7 - Jul 9^th, 2009, 10:18pm if you apply +ve voltage it will attract all electrons from nwell..so this is accumulation..how inversion will come?
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Dipankar Community Member Offline Posts: 59	Re: MOSCAP Reply #8 - Jul 10^th, 2009, 7:00pm Dear Raja, The crux is nmoscap in nwell gives a monotonic CV curve. That's the motivation behind the structure - creating a mos-varactor.
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