Goal: evaluate delay of a comparator to a slow ramp where the trip point is a variable parameter that is stepped across input range with virtuoso 6.1.6 spectre.

I.e ramp slews from 0 to 5V, trip point is a list of voltages e.g. 1.1, 2.2 3.3 4.4.

Each run the output trips in the display, but I want to quantify the delay with parametric simulations.

Method: use cross/intercept/delay commands of the calculator

Problem(s):

1) I thought I could use delay to select the difference between input crossing a voltage & the output crossing midscale. But I can't see how to tell the delay function to look at a parameter for the trip point on the input.

2) If I compute the output switching time with cross I get a table of floating point numbers. Then if I evaluate the inputs crossing with intercept, I get another table of FP numbers. I thought great, I'll just subtract one from the other. but all that appears in the result is the intercept value.

3) Then I thought well, I'll evaluate the output switching time with another intercept statement. then I will have apples & apples in the subtraction. but the calculator tells me that subtracting intercept from intercept is invalid.

How do I do this?