How to reduce noise??

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How to reduce noise??

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guamak_menanak

Joined: 13 Apr 2004
Posts: 139
Location: malaysia

01 Jul 2004 8:36 How to reduce noise??

Can any body suggest how to minimize the noise generated by the diff amp?

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santhoshv78

Joined: 22 Jun 2004
Posts: 72
Helped: 1

01 Jul 2004 8:57 Re: How to reduce noise??

Having high gm for input transistors and low gm for load transistors reduce the noise factor.

brmadhukar

Joined: 21 Jun 2002
Posts: 844
Helped: 29

01 Jul 2004 9:12 Re: How to reduce noise??

R u getting noise in simulation itself or on circuit. If it is on cicuit use proper power supply bypass and higain amplifier. If it is in simulation do as sggested in first reply.
Hope this helps

Regnum

Joined: 17 Jun 2004
Posts: 264
Helped: 12
Location: Hurlingham

01 Jul 2004 10:03 Re: How to reduce noise??

Put it to run into the refrigerator Smile

Smile

sorry, just kidding

barrybear

Joined: 22 Nov 2001
Posts: 257
Helped: 5

01 Jul 2004 10:36 Re: How to reduce noise??

Ensure that all the active components have the same gain factor ( by measuring each component and matching).

Barrybear

sunking

Joined: 25 May 2004
Posts: 914
Helped: 46

02 Jul 2004 2:11 Re: How to reduce noise??

Another way is change input stage to PMOS

hanjiemy

Joined: 11 Jun 2004
Posts: 54

02 Jul 2004 8:13 How to reduce noise??

The noise contribution of PMOS and NMOS current sources increases in proportion to their transconductance. This trend results in a trade-off between output voltage swings and input-referred noise:for a given current, as implied by gm=2Id/(Vgs-Vth), if the overgrive voltage of the current sources is minimized to allow large swings, then their transconductance is maximized.

guamak_menanak

Joined: 13 Apr 2004
Posts: 139
Location: malaysia

02 Jul 2004 8:39 Re: How to reduce noise??

Thanx for your replies!

Feedback can be used to decrease the noise! Can anybody show me how tge feedback can be implemented on that circuit?

Instead of increasing gm and using PMOS as the input stages, what is other suggestion form others?

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hanjiemy

Joined: 11 Jun 2004
Posts: 54

02 Jul 2004 8:50 How to reduce noise??

i think u can add a few picos Cap connect VDD to the Gate of PMOS bias.

guamak_menanak

Joined: 13 Apr 2004
Posts: 139
Location: malaysia

02 Jul 2004 9:06 Re: How to reduce noise??

hanjiemy Posted: 02 Jul 2004 15:50 Post subject: How to reduce noise??

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i think u can add a few picos Cap connect VDD to the Gate of PMOS bias.

What is the reason to add the caps?

sunking

Joined: 25 May 2004
Posts: 914
Helped: 46

05 Jul 2004 2:15 Re: How to reduce noise??

Add RC filter can reduce the noise too

hanjiemy

Joined: 11 Jun 2004
Posts: 54

05 Jul 2004 3:10 How to reduce noise??

Capacitor C in the bias line is needed to stabilize the circuit. C also reduces the bandwidth of the opamp resulting in lower noise.

(if wrong, pls put it right)

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