Definition
The capacitance measured at the input terminals of an electronic circuit or device, which appears as a load to the source driving that input. In avionics and aircraft electronic systems, input capacitance affects how quickly a signal can rise or fall at the input and how the input interacts with the impedance of whatever is feeding it.
Plain English
How much electrical 'storage effect' a circuit's input has when something is connected to it. A higher input capacitance slows down fast-changing signals coming into the device.
Context Anchor
Seen in avionics, sensor, antenna, and electrical circuit specifications or troubleshooting information.
Derivation
From 'input' (the point where signal enters) and 'capacitance' (the ability to store electrical charge, from Latin capacitas, 'ability to hold'). Together: the charge-storing behaviour seen at the entry point of a circuit.
Why Pilots Care
High input capacitance can load down weak signals from sensors or antennas, leading to reduced accuracy in navigation and communication systems.
Grounding Statement
At the input of a device, even a very small ability to hold charge can matter when the electrical signal is changing rapidly.
Intuition Check
Input capacitance is not an input command or setting. It is an electrical property of the circuit at the point where the signal enters.
Example Sentence 1
The technician checked the amplifier's input capacitance to confirm it matched the value listed in the maintenance manual.
Example Sentence 2
Excessive input capacitance in the audio amplifier caused the microphone output to sound weak and distorted.