Fan-in is the number of a logic gate’s inputs
Fan-out is the number of gate inputs connected to this logic gate
Parasitic capacitance is the unavoidable plague of electronic circuits. It makes circuits affect the other close circuits in an unwanted manner, which causes them to behave differently. The sum of all the capacitances gives the capacitance of that logic gate.
A capacitor takes time to charge and discharge → Kirchhoff’s law
- Charging :
- Discharging :
The speed, or delay, depends on how fast the load capacitance is charged
- With higher fan-in the per-input capacitance is higher
- With higher fan out, the higher total load capacitance
The higher the capacitance, the slower the gate is