Virtual ground split supply circuit-Stability

Hari,

If you drive a capacitive load,  an open-loop output impedance, Ro, forms a pole with Cload which depending on the size of the CL may lead to instability.  Whereas any additional impedance inside the closed-loop makes things worse from stability point of view, adding a resistor, Riso, in series with the output outside of the loop forms a canceling zero in the close-loop transfer function thus improving the phase margin.

Of course, if you also drive a resistive load, adding Riso resistor will lead to a gain error due to resistive voltage divider.

For more details in this regard, please watch a series of TI Precision Labs videos under following link: