I'm having a senior moment and would appreciate clarity.
I'm working on an inverting amplifier design where I need to add low-pass filtering and a voltage clamp.
Without the filtering and clamp, the op-amp configuration would simply be a feedback resistor from output to (-) input and the input resistor from signal source to (-) input.
Worst case error is the sum of the resistor tolerances but statistical averaging usually gives better results than worst case. The figure that I've used in the past is the inverse of the square-root of the number of components (about 0.7% if using 1% resistors).
Now I'm going to split the input resistor into two equal-value resistors, half the value of the original single resistor.
Intuition says that the statistical average error now decreases slightly to the inverse of square-root (3) or about 0.58% if using 1% resistors.
Am I out to lunch or is this a reasonable assumption to make?
Note: the worst case error is still 2% in both cases. Worst case error is what I use when I'm calculating my total error, statistical average is the number I use when estimating the typical error.