Franco Tiratore wrote:
>
>
> Thanks again, Andor.
> According to the guys of comp.arch.fpga, on an FPGA for OFDM in 802.11a
> I have to implement a fixed-point FFT. Then the FFT is not a problem at
> all.
>
> Ciao,
> Franco
>


Well, you don't HAVE to implement it in fixed point. You can do it in
floating point on an FPGA, but it really isn't necessary for OFDM and
adds considerable complexity. FWIW, I've developed a
floating point FFT for virtex4 that does ieee single precision floating
point FFTs at 400 MSamples/sec complex continuous data. That's 160ns
for a 64 point FFT. Latency through the pipeline for a fixed size 64
point transform is about 400 (1us) clocks input to output including the
reordering to present data at both ends in natural order.