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Registered: ‎02-03-2020

design of FIR filter

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i designed FIR filter by using DDS compiler ..

1) input of FIR compiler =DDS compiler output 

my question is  after simulation of FIR compiler how can i identify that i got correct result.

specification given:

DDS:

1) Clock = 200MHZ

2) output clock =20MHZ

FIR COMPILER:

1) coefficent file =129 tap

2) Input sampling frequency = 200MHZ

3)clock frequency=200MHZ

 

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Teacher
Teacher
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Registered: ‎07-09-2009

Re: design of FIR filter

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from what I undersand

You have made a FIR filter,

   Im guessing you have some sort of design spec. 

           e.g. for a low pass filter, you want a pass band and a stop band responce.

Your then adding a DDS as a sin wave gennertato to the input ?

What you do then is send one frequency out of the DDS, and you will get one amplitude out of your FIR

     so select a pass band frequency, and a stop band frequency, and run the simulation

An enhancment, you could get the DDS to sweep up, and see the amplitude change.

  but this is goign to take a fair amount of simulation time,

 

Just a note. Now days its unusual to realy design a FIR filter, with the free tools available, you just put in the responce you want, and it spits out the coeficients you then plug into the FIR designer.  Indeed, most of the tools can make the FIR cde for you as world.

 

 

<== If this was helpful, please feel free to give Kudos, and close if it answers your question ==>

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Teacher
Teacher
258 Views
Registered: ‎07-09-2009

Re: design of FIR filter

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from what I undersand

You have made a FIR filter,

   Im guessing you have some sort of design spec. 

           e.g. for a low pass filter, you want a pass band and a stop band responce.

Your then adding a DDS as a sin wave gennertato to the input ?

What you do then is send one frequency out of the DDS, and you will get one amplitude out of your FIR

     so select a pass band frequency, and a stop band frequency, and run the simulation

An enhancment, you could get the DDS to sweep up, and see the amplitude change.

  but this is goign to take a fair amount of simulation time,

 

Just a note. Now days its unusual to realy design a FIR filter, with the free tools available, you just put in the responce you want, and it spits out the coeficients you then plug into the FIR designer.  Indeed, most of the tools can make the FIR cde for you as world.

 

 

<== If this was helpful, please feel free to give Kudos, and close if it answers your question ==>

View solution in original post

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Explorer
Explorer
250 Views
Registered: ‎04-19-2018

Re: design of FIR filter

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You can:

a) Feed your filter with either a single frequency signal (sine wave) or white noise and take the FFT of the output. The result should match your filter specification. This is an approximate validation.

b) Implement your filter in a know simulator (Matlab, etc) and in your FPGA. Feed the same input and compare outputs. 

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Scholar
Scholar
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Registered: ‎04-13-2015

Re: design of FIR filter

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chaitanyaece.stu@nita.ac.in , FIR filters are the easiest filters to verify:

- feed a single pulse (e.g. 1,0,0,0,0,0,0....) to the filter and look at the output: if all is OK the output will be exactly the pulse amplitude time the individual coeffients.

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