Multiple Reflections from RC Loading of Pulse-Signal Transmission Lines

Abstract—An analysis is made with equations developed for the capacitive effect of RC loading with multiple reflections on pulse-signal transmission lines. The capacitive hold waveshape and hold time are described and compared with experimental results. Isolating the capacitive effect from the purely resistive case is accomplished so that this effect can be used to modify existing solutions. The analysis results show that a significant capacitive hold time occurs before the wave approaches its final value with oscillations occurring about the initial voltage value. The number of cycles of oscillation are equal to the number of times the wave has been reflected, and the amplitude of oscillation increases with each cycle. These effects are independent of transmission line length. Results are applicable for any system with RC loading and transmission-line effects and, in particular, for high-speed pulse systems. The mathematical results can either be directly applied in reflection analysis or the relative capacitive hold-time results can be added as a corrective factor.