1. Chip size. You need to know what kinds of package will be used.1 t6 Y) |8 o: B! }0 g& _
2. Pad location. You need to confirm with supplier about the bond wire bonding. G" n4 o* L, o% B1 b
3. ESD and latchup consideration. % h* ^5 p. i1 e4 w o y
4. Any noisy circuit inside the circuit. If yes, you may need to isolate those noisy circuits with double guard ring or individual ground and power path.7 s' g- T8 Y* L
5. The current consumption on the whole circuit. It will affect the metal width of each building block and the whole circuit.. w8 S$ _# r4 Q
6. Make sure there is no softcon connection.* N& e- ~; c9 w
7. How many metal layers could be used ?9 C( i- A$ O- `" D! B+ Z6 y
8. Metal Density consideration.