Hi,
can someone please explain what is the exact role of the filters below.
The circuit is designed to amplify a low voltage signal( 0-10mV) 100 times.
But I dont see why are the filters exactly used?
Here is the circuit:
View attachment 279231
Thanks

 

hi niss,
The C1 blocks the DC component of the Vout signal, together with R5 as an intermediate load.

R8 and C2 are a low pass filter.
Where is the Vinp of the INA connected, is it a 'noisy' voltage.?
E

BTW: Is this Homework.?

 

C3 reduces power supply noise.
C1 blocks DC but passes frequencies above 3.2Hz (-3dB).
C2 and R8 might be a lowpass filter that passes low frequencies and cuts high frequencies.

 

hi niss,
The C1 blocks the DC component of the Vout signal, together with R5 as an intermediate load.

R8 and C2 are a low pass filter.
Where is the Vinp of the INA connected, is it a 'noisy' voltage.?
E

Hi, thank you for your answer.
So are C1 and R6 high pass filters?
So do we consider both together as a bandpass?
Inputs are connected to electrodes placed on the skin to measure the voltage of the muscles.
(No it is part of a project Im working on)

 

C1 and R6 is a single pole high pass filter. R8 and C2 are a single pole loww pass filter. They may work well in combination, but I can't tell by looking at them. That would take additional time to do an analysis.

 

C1 and R6 is a single pole high pass filter. R8 and C2 are a single pole loww pass filter. They may work well in combination, but I can't tell by looking at them. That would take additional time to do an analysis.

thank you

 

hi niss,
We discussed this INA a week or so ago.
This is the response I see, assuming a skin/muscle resistance of say 10k.
E

 

hi niss,
We discussed this INA a week or so ago.
This is the response I see, assuming a skin/muscle resistance of say 10k.
E
View attachment 279236

Yes, thank you
I was asking about the use of the filters and also if I need to change them with active filters or not in this case.
Btw I changed R5 to 10k and R6 to 1k

 

C3 reduces power supply noise.
C1 blocks DC but passes frequencies above 3.2Hz (-3dB).
C2 and R8 might be a lowpass filter that passes low frequencies and cuts high frequencies.

thanks

 

hi niss,
R5/6 changed.
E

Update: @nissafha
To choose a suitable filter, you must have an idea what are the range of frequencies of interest that you expect from the Vin source, and then filter out any unwanted low or high frequencies.
Do you have an image showing the expected signal input?

 

hi niss,
R5/6 changed.
E
View attachment 279237

the desired frequency range is between 15 and 150kz

 

hi nis,
This shows the Vo1 and Vo2 of the project.
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