Architecture diferences in fpga(LUTs and FFs)

[his_grace]

for any FPGA(be it spartan, virtex, any) with x no: of CLBs, is it necessary to have
1. no of slices- 2x
2.no of LUTss- 4x
3. no of FFs- 4x
Is there any particular/fixed ratio for these.

I found this to be the case in virtex fpga.

 

[permute]

Look at the CLB user guide for the parts you are interested in. These have changed over the years, and there are some extras in there as well (muxf7, muxf8, xorcy). The 7-series has 4 lut/slice, and 8 ff/slice with some restrictions on 4 of the ff's.