Re: FGPA Applicaiton??
The need for an PLD (FPGA or CPLD) depends on some parameters IMHO.
Speed, databus width, pre-processing need, etc.
There are also ADCs with a serial output (mostly used in audio range).
If you have a high speed ADC (>100MSPS) you will have a lot of problems getting the data from that ADC to the µP or µC. DSP alikes have better capabilities to process these streams of data.
If you want a digital filter in front of your DSP/µP, and a serial output, there is currently only one option FPGA + SerDes (whether or not integrated). A, X and L have products in this area. (Stratix, Virtex2, XPGA).
Some of the ADCs are only capable of presenting the data (full rate) in differential mode (LVDS, ECL). Again, then you will require so glue to pre-process.
Hope this helps