How can I remove electronic noise?

Question

I have an analog circuit. A small signal is amplified by about 400 times. The problem is that the noise is also being amplified. How can I remove this noise other than filters and decoupling capacitors?

Thanks

Answer 1

Search for the cause of the noise, gain of 400 is not that high, but what is the measured level of the noise, referenced to the input? If it's microvolts, it may be normal. What does the noise sound like, is it 60/120Hz line noise, or is it high frequency random noise?

If it is HF noise, it may be normal, but you can filter it out, depending on the use of the circuits.

Or try to determine the source of the noise. Check the input components in the very first stage. You may have a noisy resistor. You may have to substitute a low noise transistor for the first stage. Or the impedance of the input may be too high, and a redesign for the first stage is needed.

If it's LF noise, it could be pickup from other parts of the room, like flourescent lights, and you may have to shield the circuit. Or possibly the PS (power supply) may be noisy.

Did you decouple the PS at each stage? Add a 100 ohm resistor in series with the power to the first stage and add a 100uf bypass cap.

Make sure you tie all the grounds together with a piece of #20 wire.

.

Answer 2

ferrites? screened cable? is the noise coming from a power supply?

Answer 3

No too much, the other option you have is a selective amplifier, in this way you amplify your signal but no the noise.

Usualy is a amp with a filter or decoupling in the feedback branch.

Answer 4

Pls check whether the circuit is properly grounded. A bad soldering also will introduce noise which will be duly amplified!!