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poly resistor vs nwell for 1/f noise (Read 1081 times)

rfcooltools.com Senior Member Offline Posts: 159	poly resistor vs nwell for 1/f noise Jun 28^th, 2010, 2:23pm poly sheet rho 310 Ohms/sqr nwell 890 Ohms/sqr same total area 1/f noise for poly is 20x greater than nwell! Can anyone shed some light on this? is it right? http://rfcooltools.com
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vivkr

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Re: poly resistor vs nwell for 1/f noise
Reply #1 - Jun 29^th, 2010, 5:23am

If I had to take a guess, I would say that the higher 1/f noise in poly resistors is expected due to 2 reasons:

1. Poly is semi-crystalline (polycrystalline if you will) and hence the likelihood of greater number of places for electrons to get trapped, although.

2. An Nwell resistor likely has much more current flowing away from the silicon surface and hence fewer traps.

That being said, I would imagine that the trends ought to be very strongly process dependent. Any process guys out there?

Vivek

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rfcooltools.com

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Re: poly resistor vs nwell for 1/f noise
Reply #2 - Jun 29^th, 2010, 1:13pm

vivkr,

Thanks for your reply, I did some checking around and your assessment is consistent with the info I have picked up.
here is what I found
charge trapping and de-trapping events at the poly-silicon boundaries is the cause of 1/f noise in poly resistors. While I have not been able to find any literature on nwell 1/f your explanation of current not traveling at the surface seems reasonable since crystalline Si has minimal traps.
Thanks,
http://rfcooltools.com

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hande.vinayak Junior Member Offline Posts: 22 BOM	Re: poly resistor vs nwell for 1/f noise Reply #3 - Aug 18^th, 2010, 5:04am Please, can you tell me the flicker noise in MOSFET or Poly resistor or NWELL resistor is more dominant? Thanks.
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