hello, How to reduce 1/f output noise of amplifier?

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hello, How to reduce 1/f output noise of amplifier?
 

One choice is to use a first transistor with lower 1/f noise.

Another is to use a step up transformer to raise the source voltage which allows you to reduce the gain of the active part of the amplifier. This usually works if the amplifier input impedance is much higher than the source impedance. This option is overlooked in modern days because transformers cost much more than small signal transistors.

If there will be no wanted signal components at these low frequencies, you can move the low end 3 dB frequency higher.
 

I think using PMOS instead of NMOS can reduce 1/f noise. Is that true?
 

To reduce the 1/f noise:
1) use a PMOS input transistor instead of a NMOS. The Flicker noise is lower, but has the mobility is also lower, you'll need bigger transistor (which mean higher input load) or higher current for the same gain
2) use a big input transistor. Flicker noise has a 1/W rule. But again increasing the size of the transistor increases the input cap.
3) use chopping. you can almost completly cancel the noise. but it means you need to add the switches, the clock. if you use switched cap circuit, it's not a problem, but for continous time it might add some difficulties
To my knowledge those are the main techniques...
 

you can use latel npn as input transistor to reduce 1/f noise
 

princerock said:
I think using PMOS instead of NMOS can reduce 1/f noise. Is that true?
Click to expand...

This is true. But it's said that this will be not true anymore in more advanced technology.
 

whats the frequency u r designing at??? Depending on that solutions may vary as far as i know.
 

1.try to use pmos instead of nmos;
2.increase the device area WL,at the same time,make sure other parameters were not influenced
 

use pmos and increase device area
 

hi there, what is PMOS n NMOS? is it mean P and N type of MOSFET transistor?
 

I agree to the comment that the frequency of operation is important to sort out this problem. Even if the accuracy requirement is too high the the given solution of using pmos may not be capable of doing so. That time you may have to intoduce some calibration technique etc. to sort it out.
 

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