I have tested the input stage (with the exceptions of the 2 relays). I'm using as signal generator an HP 8116A, (50 MHz sin,saw,square)... the frequency response is quite flat, and I can compensate the input stage with the input compensation network I designed.
I'm using an old Tektronix 2205-40 as oscilloscope... not the best this days... but good enough for the job.

I have also finished to design the FPGA (for the time being) and in the next few days I need to go back on the SW side and design the API to communicate (from my SW) with the FPGA.
To do this I'm using a FTDI chip that is delivered with a *.dll that simplify the design of the API!

Keep watching the next few days this blog! I bet at the end of the week I will be able to see some waveforms from my GUI.