Hi, Arash.
Short answer to all your questions is FDATool. It can quantize the coefficients and generate HDL implementation.
Is it good to design one first order IIR filter in Matlab and then change it`s coefficients with mine? Or other way?
But you don't need to design new filter. If you have calculated the coefficients, then just import them (File -> Import Filter from Workspace).
Best Regards,
Vitaly.
