The following factors define the performance of a logic gate:
Supply voltage: TTL IC logic gates are normally designed to operate with a supply voltage of 5 V whereas CMOS gates can operate in the range of 1–30 V. When a supply voltage of 5 V is specified for a gate, it is expected that the voltage variation remains within ±0.25 V of 5 V for reliable gate operation.
Input voltages and currents: For a gate to operate properly, it should have minimum high-input voltage, VIH(min), which represents the logic 1 input level.
As an example, let VIH(min) = 2 V for a gate. It means that the output of the gate changes only when the input is greater than or equal to 2 V. Consider the transistor inverter ...