SNVSB29C October 2018 – June 2021 LM5143-Q1
Figure 9-3 shows a Type-II compensator using a transconductance error amplifier (EA). The dominant pole of the EA open-loop gain is set by the EA output resistance, RO-EA, and effective bandwidth-limiting capacitance, CBW, as shown in Equation 28.
The EA high-frequency pole is neglected in the Equation 28. The compensator transfer function from output voltage to COMP node, including the gain contribution from the (internal or external) feedback resistor network, is calculated in Equation 29.
The EA compensation components create a pole close to the origin, a zero, and a high-frequency pole. Typically, RCOMP << RO-EA and CCOMP >> CBW and CHF, so the approximations are valid.