Statistical method of noise estimation in a synchronous system

This paper describes a process developed by IBM engineers and programmers to analyze coupled noise within a synchronous digital machine. Former methods simply summed noise components or used root mean square techniques to estimate the total cross-talk on a quiet line. A method that considers the spatial relationship of the noise generating components as well as the timing of the incident pulses is discussed. Consideration is given to factors such as path delay, reflected noise, driver slew rate, noise pulse width, termination, net topology, noise from other sources and the probabilistic nature of the time when a signal is launched as well as other parameters. The result is a probability of achieving a noise level on the circuit and a noise versus time envelope. The method is more accurate than previous techniques due to timing and statistical considerations. Treatment of the resultant output is discussed and compared to simpler deterministic methods. Failure criterion, critical time periods and some sources of errors are also considered