Terminating transmission lines

摘要

Aresistor's purpose in life is to convert electrical energy into heat. That's all it does. Period. But this humble singular purpose can be applied to countless applications, including the termination of high-speed transmission lines. Why terminate? When electrical current flows through a resistor, some or all of the energy in that electrical current is converted to heat and is lost forever. We call this electrical-to-heat conversion electrical "loss." When electrical information is transferred from one physical location to another, transmission lines are often used as the high-speed conduits of this information. Resistive terminations make use of their ability to convert electrical energy into heat to prevent reflections. The type of resistor, spectral content of the signal, and the length of the transmission line are all important aspects of proper transmission-line design and termination. Thin-film resistors designed with minimal parasitic capacitance and inductance make the best resistive transmission-line terminators.