Input current in logic gates refers to the current required to maintain the input at a high or low state, which varies by logic family; bipolar TTL gates draw more input current due to their use of NPN transistors, while CMOS gates require significantly less as they utilize MOSFETs. Quiescent supply current is the current consumed by a gate when it is not actively switching, indicating the power drawn during static input conditions. Understanding these currents is crucial for designing efficient digital circuits and managing power consumption. The equivalent circuit of the gate provides insights into the current flow. Proper knowledge of these parameters aids in optimizing logic gate performance in electronic applications.