FIR filter in Matlab for bandpass 250kHz - 700kHz and sampling frequency 250MSPS

[umaair_653]

Hi all,
I want to design filter to implement on FPGA with a mentioned parameters in subject but when i am starting to design it on matlab fdatool, it gives very high order filter result, and when i decrease or set by myself upto 10 order its impulse response is not good as i want.

I am using high speed ADC with 250MSPS.
Any idea will be highly appreciable.
Regards,
Umair

[Stephan_D]

Hi umaair_65,

If the order of the selected filter is very high, because you need a high attenuation or a specific inpulse response, than it is the result of the design parameters.

I think you can only

- Change the type of filter (IIR instead of FIR)

- Change the parameters (cutoff frequency, ...)

- Use multiple filters instead of one filter

Regards, Stephan

[umaair_653]

Hi Stephan,

If i go with second option of changing the place of cutoff frequency like 5MHz then may be it will give better response but what do you think it will create a problem when i will implement this on FPGA?

Secondly if i go with the same second number solution for high pass filter, i have already analysed in Matlab a high pass filter with 50 order and it gives better impulse response on FDATOOL but again my question is,it will affect the signal of between BP filter range??

Thanks,

Umair

[Stephan_D · Accepted solution]

Hi Umair,

you can theoretically designe any filter you want on a FPGA. If you can implement the filter on a give FPGA-Target is another story.

There are usally some limitations on a FPGA, which you have to take into account:

- Number of FlipFLops, LUT, ...

- Maximum loop rate

- Number of available multipliers

It is almost not possible to tell you, if you can implement your filter on a given FPGA-Taregt. The only way to get the proper answer is to try it. A filter with order=50 could be really large and maybee doesn't fit on the FPGA or doesnt meet the loop rate which you need.

I don't use the FDATOOL, so I can't give you an answer to your second question.

Stephan

[umaair_653]

Thanks Stephan,

Umair