Today I was tasked with determining the output resistance as seen by the load resistor, RL, in the circuit below. As far as I can tell, the circuit is a current generator, whose output current solely depends on the size of Rf (and the current in Rf should equal the current in RL since no current goes to the non-inverting input of U1 due to the summing point constraint), and is thus completely independent on the load resistor, which in turn would mean that the output resistance (given ideal components) is infinite, but I am by no means sure, as I've no way of proving it. Am I correct in my assumptions? How would I approach an actual analysis of this circuit? And apologies for the lackluster title. Forum wouldn't let me write anything more than a single word.