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

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.

Any idea will be highly appreciable.

Regards,

Umair

Answer 1

[Honglei Chen]

If you are interested in the band between 250 kHz and 700 kHz only, then you can decimate your signal to, say 2 MHz first. Then you don't need a filter with such high order to satisfy your requirement.

HTH.

Answer 2

[Umair]

thanks for your reply, can you tell me how to decimate the signal?? and it will not effected by very high sampling frequency which is about 250MHz?? and i am going to use high speed ADC will it works with that??

[Honglei Chen]

You can use decimate function to do that

http://www.mathworks.com/help/signal/ref/decimate.html

to go from 250MHz to 2MHz, you need to decimate by a factor of 125. It basically drops the samples in between since you really don't need a sample rate that high