[casper] bit width setting of pbf filter and fft widtband

[Wan.Cheng]

Hi:

Is there any instructions to set the bit width of PFB and FFT?

When I set output bitwidth of PBF to 25, I get a wrong spectrum output. But it 
works well when the bitwidth is set to 18.

I guess something might be over flow in the FFT block.

Any idea on the bitwidth of PFB and FFT?

Thanks

Wan