Termineringsmotstånd

Termineringsmotstånd, often shortened to "terminator," is a resistor used to terminate an electrical transmission line. Its purpose is to absorb the energy of signals traveling down the line, preventing reflections. Reflections occur when a signal encounters an impedance mismatch at the end of a transmission line. These reflections can cause distortion, data corruption, and timing errors, especially in high-speed digital systems.

A properly terminated transmission line presents an impedance to the incoming signal that matches the characteristic impedance of the line itself. This impedance matching ensures that the signal is fully absorbed by the terminator, rather than being reflected back towards the source. Common characteristic impedances for transmission lines include 50 ohms and 75 ohms.

Termineringsmotstånd are crucial in various applications, including Ethernet networks, video signal transmission, and computer bus systems. In older Ethernet standards like coaxial cable implementations (e.g., 10BASE2 and 10BASE5), terminators were physically attached to the ends of the coaxial cable. In modern systems, termination is often implemented at the interface circuitry of the transmitting and receiving devices.

There are different types of termination. Active termination uses a more complex circuit to provide a more precise impedance match, while passive termination uses a single resistor. The choice of termination method depends on factors such as signal frequency, line length, and desired signal integrity. Proper termination is a fundamental aspect of designing reliable high-speed electronic systems.