rfic specification

Hi,
I am defining the specifications for a new RF IC. What is the procedure that I should follow?

1) Define all the functions ( Direct down conversion or two stage down conversion, ADC, LNA (NF, gain,... ) Digital Functions) and then the architecture and process

OR

2) Fix the process (CMOS, SiGe,...) and architecture and see what functions can be added.

Thanks in advance
Madhukar

This IC is to perform a defined function. You should specify the terminal parameters (electrical, mechanical, and thernal)

Let the person who designs it decide the block diagram and the chemical properities (silicon, etc.)