I'm interested in the limits you encounter if you try to add many inputs into an op amp summing circuit. I've read that the inverting configuration is more natural for adding many inputs since the gain for an input is just determined by the feedback resistor and the resistor on that particular branch. Is there a maximum number of inputs you can get away with?
This answer maximun number of inputs on a opamp adder circuit (dealing with a non-inverting amplifier) says that noise is a limiting factor as you add each input. I guess I would assume that the noise would add in quadrature so that the noise would go as sqrt(N) for N inputs. Is this right - and are there any other factors that would limit you from adding inputs indefinitely? Thanks!