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2nd order low pass filter in matlab (Read 4633 times)
singh
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2nd order low pass filter in matlab
Nov 2nd, 2011, 9:02am
 
how to omplement 2nd order low pass filter??

i want to check noise due to amplifier and have got rms value of the noise transfer function vs frequency as 2 |sin(x)| . i want to multiply this rms value with the low pass filter to check the noise of amplifier (which is from 0 to some frequency as flicker noise,then white noise )...this can be done using 1st order or 2nd ordr low pass,..how to implement 2nd order low pass filter in matlab?

please help regarding this
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« Last Edit: Nov 03rd, 2011, 8:43am by singh »  
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rfcooltools.com
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Re: 2nd order low pass filter in matlab
Reply #1 - Nov 3rd, 2011, 11:48am
 
singh,

I am not sure why the noise vs frequency you stated is 2*|sin(x)| the noise transfer function vs frequency would probably be something similar to N(s)=Const*(1+s/f1f)/(s)
For the filter you know the order so you pick the type by using butter, cheb, ellip etc obtain coefficients of numerator and denominator of the filter polynomial.  Then generate the filter by calling freqs to check the response of just the filter.   freqs returns a vector H at omega, multiply 20*log(H*N(omega)).  

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