Lähtöimpedanssin

Lähtöimpedanssi, also known as output impedance, is a fundamental concept in electrical engineering that describes the opposition to current flow encountered when a signal or power source is connected to a load. It is a measure of how effectively a source can deliver power to a load. Ideally, a voltage source has zero output impedance, meaning it can deliver any amount of current without its voltage dropping. Conversely, a current source ideally has infinite output impedance.

In practical terms, output impedance is the impedance looking back into the output terminals of a source or amplifier. It is typically represented by a complex number, consisting of both resistance and reactance. This impedance affects the voltage delivered to the load, particularly when the load impedance is not significantly larger than the output impedance. The voltage division between the source's internal impedance and the load impedance will result in a lower voltage reaching the load than the open-circuit voltage.

Understanding and matching output impedance to load impedance is crucial for maximizing power transfer, minimizing signal distortion, and ensuring proper operation of electronic circuits and systems. For instance, in audio systems, a low output impedance is generally preferred to drive loudspeakers effectively and maintain audio fidelity. In radio frequency circuits, impedance matching is essential for efficient power transfer and to prevent signal reflections.