AD8618 Spice model and input capacitance

I've got a circuit that's not behaving as predicted by the AD8618 spice model included with LTSpice XVII (version 17.0.22.0).

It appears the common mode input capacitance (7.8pF according to the data sheet) is not included in the spice model. Nor does it seem to be in the AD8615 model I separately downloaded. 

Anyway, it would have saved me a bit of time and effort if the common mode input capacitance was properly modeled. Please consider adding this to the model.

Or, you can tell me I'm all wet and I'll check my work again...but it sure looks to me like that's missing from the model.

  • 0
    •  Analog Employees 
    on Feb 22, 2021 8:14 AM

    Hi,

    Thanks for pointing out. The common-mode input capacitance was not modeled both on AD8615 and AD8618 spice models, we'll consider adding this in the future revision.

    For the mean time, you can add an external common-mode input capacitance for instance on the non-inverting pin to ground to emulate the effect of the model common-mode input capacitance.