päätevastuksilla

Päätevastus, also known as a termination resistor, is a resistor placed at the end of a transmission line or signal path. Its primary purpose is to absorb the signal energy that reaches the end, preventing reflections. When an electrical signal travels along a transmission line, it has a characteristic impedance. If the end of the line is not terminated properly, the signal encounters a mismatch in impedance. This mismatch causes a portion of the signal to be reflected back along the line. These reflections can interfere with the original signal, leading to distortion, data corruption, and reduced signal integrity, especially in high-speed digital systems and radio frequency applications.

By matching the impedance of the termination resistor to the characteristic impedance of the transmission line, the signal energy is dissipated as heat within the resistor. This effectively terminates the line and minimizes or eliminates reflections. Common impedance values for transmission lines include 50 ohms and 75 ohms for coaxial cables, and 100 ohms for twisted-pair Ethernet cables.

Päätevastukset are crucial for maintaining signal quality in various electronic systems. They are found in computer networks, video transmission systems, and high-frequency circuits. Without proper termination, the performance and reliability of these systems can be severely compromised. The selection of the correct termination resistor value is critical and depends on the specific transmission line impedance being used.