An extension of Elmore's delay

This work extends the notion of delay defined by Elmore [3] to accommodate the effect of non-unit-step (slow) excitations. A single value of delay for any node in an RC network is derived by using a state-space model. This model provides a compact delay expression in closed-form. It also handles multiple sources of excitation, and we show that delay estimation for slow excitations is no harder than for unit-step input.