Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Intrinsic noise of a MOSFET

Status
Not open for further replies.

bharath_k

Junior Member level 3
Junior Member level 3
Joined
Jun 8, 2018
Messages
31
Helped
0
Reputation
0
Reaction score
0
Trophy points
6
Activity points
244
Hello everyone,

I want a random noise generator. I will feed the random noise to a comparator and then use this signal to trigger a oscillator.

So can I use the intrinsic noise a MOSFET as my noise source? if so how do I simulate this?

Thanks,
Bharath
 

SPICE has some noise analyses but they may or may not be
useful to you.

The qualities of the noise product matter to some folks
more than others. Zener diodes are liked because they
make a pretty good "white" noise. Devices which have
other dominant noise mechanisms may give you some
"clicks, pops" (popcorn noise, shot noise, RTS) that
offend the ear. At the other end you have the kooks and
spooks at the NSA, who insisted their "randomizer" ICs
produce (at test) a very even distribution of the random
number output over time (which is more difficult than
you might imagine - the pursuit of perfect imperfection).

If you want to observe time-domain randomness then
you's probably need two things. One is a simulator with
'tnoise' (transient noise) analysis and the other is a set
of models with the pertinent noise model params in
place w/ sane values. You'd probably have to do some
reading to find out what noise behaviors are and are not
considered "well covered".

Frequency / phase noise domain, is more for getting a
rollup noise quantity than for "looking at" although you
can get some useful design insight from seeing how the
noise voltage increases along the lineup (weak link etc.).

For maximum noise you'd use the smallest gate area MOSFET
(and maybe extend this into any amplifier chain, more
noise there).

A "digital" technology may have poor or no noise model,
a RD or mixed signal CMOS is likelier to have accurate(-ish)
noise params and maybe even some simulation-vs-model
reportage in the PDK docs.
 

    bharath_k

    Points: 2
    Helpful Answer Positive Rating
SPICE has some noise analyses but they may or may not be
useful to you.

The qualities of the noise product matter to some folks
more than others. Zener diodes are liked because they
make a pretty good "white" noise. Devices which have
other dominant noise mechanisms may give you some
"clicks, pops" (popcorn noise, shot noise, RTS) that
offend the ear. At the other end you have the kooks and
spooks at the NSA, who insisted their "randomizer" ICs
produce (at test) a very even distribution of the random
number output over time (which is more difficult than
you might imagine - the pursuit of perfect imperfection).

If you want to observe time-domain randomness then
you's probably need two things. One is a simulator with
'tnoise' (transient noise) analysis and the other is a set
of models with the pertinent noise model params in
place w/ sane values. You'd probably have to do some
reading to find out what noise behaviors are and are not
considered "well covered".

Frequency / phase noise domain, is more for getting a
rollup noise quantity than for "looking at" although you
can get some useful design insight from seeing how the
noise voltage increases along the lineup (weak link etc.).

For maximum noise you'd use the smallest gate area MOSFET
(and maybe extend this into any amplifier chain, more
noise there).

A "digital" technology may have poor or no noise model,
a RD or mixed signal CMOS is likelier to have accurate(-ish)
noise params and maybe even some simulation-vs-model
reportage in the PDK docs.
Thanks a lot for your detailed analysis. After a lot of search I found in latest version of Cadence we can do transient noise analysis. So I would probably try this.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top