Oscillation and Ringing: Finding Worst-Case Capacitive Load [Shop Talk: What You Didn't Learn in School]

It's a universal problem: How do you design an analog block when you don't know exactly what the capacitive load is going to be? It is disconcerting how often this problem comes up. In the old days, there was always the threat that the customer would hang something ill-advised on your output pin. Today's systemon-chip (SOC) environment shelters most functional blocks from the application board, but you could still be blindsided by wiring capacitance on the chip itself. Basically, you won't know how much capacitance will be clinging to your creation until the layout is nearly finished, and it could change at the last minute.