Low ESR for integrators? == 

 This is another new one on me. I didnt know that low ESR was essential for integrator capacitors. Did the author really mean leakage current? I think he did, but Im willing to be persuaded otherwise.  

 :I could imagine that both low ESR and low leakage are essential to make a good integrator. Low leakage is a pretty obvious requirement; an integrator wouldn't be very accurate if the accumulating integral leaked off with time. But ESR is trickier; clearly, it affects the high-speed response of the integrator, so if the cap has high ESR, the integrator won't be able to accurately integrate short pulses. But it seems to me that ESR affects low-frequency response as well, as it causes loss of charge (to heat) that ought to end up in the capacitor. 

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 I would suggest that the effect of capacitor ESR in integrators is minimal. THe leads you use to connect the capacitor have probably got more resistance than a half decent caps ESR (0.0001 ohm say)  

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