Fan in and Fan out related to vlsi design basic circuit concepts. This will be used for IC design process. By using such key methods, the performance of the circuit in IC will be improved in a better manner.

2. It is a basic concept of that deals with the speed of transistor.
Two additional factors that influence the operational speed of a gate
need to be considered and they are
1.FAN-IN
2.FAN-OUT
Note:-
1.As fan-in have indicating that if no of inputs to gate increases then it
increases the delay.
2.As fan-out have indicating no. of loads driven by the output the gate
delay substantially increases.

6. Fan-in and Fan-out Characteristics

7. Choice of Layers:-
• In order to meet a given specification of a designer will have several
possible ways to choice the layers.
• And any designer should have commonsense constraints to be
considered.
1. VDD and Vss (GND) should be distributed on metal layers wherever
possible.
2. Long lengths of polysilicon should be used only after careful
consideration because of the relatively high RS value . Polysilicon is
unsuitable for routing VDD or Vss other than for very small
distances.
3. Diffusion layer will have moderate resistance