What is the reason that most of ICs (e.g. MCU) has multiple (A/D)GND and (A)VCC pins?
If it is to increase performance of an IC, how does it help to performance? or is it easier for the IC designer to connect some pins externally?
some footprint of ICs have a GND connection under the case, how does it help? Would it improve performance of an IC if I draw a GND under the case even if it is not required?