Although the IBB is built using an ordinary buck regulator, the small signal closed-loop characteristics are quite different from that of a buck. The most outstanding difference is that the IBB loop contains a "right-half-plane" (RHP) zero in the small signal frequency response. This zero adds a lagging phase to the loop, rather than leading phase, as an ordinary zero would contribute. As a result the phase margin of the closed loop response is reduced, leading to potential instability and poor load transient response. Equation 7 gives the frequency of the RHP zero.

Generally, the RHP frequency must be about 4 times the loop gain crossover frequency. From Equation 7 we see that decreasing the size of the inductance will increase the frequency of the RHP zero and help to keep it away from the loop gain crossover point. However, the minimum inductance may be limited by other considerations. Another way to help with this issue is to reduce the loop gain crossover frequency by using a larger output capacitance than would normally be used with a buck. This may also help with the load transient response and reduce the output voltage ripple. If external feed-back resistors are used (as in Figure 3-1), then a feed-forward capacitor across the top feed-back resistor can be used. Sometimes this capacitor can give enough phase lead to improve both the phase margin and load transient response. When selecting a buck regulator to use as an IBB, a converter utilizing current mode control is the best choice. Current mode control provides a small signal loop response with fewer poles (and less phase lag) than a voltage mode controller. This tends to reduce the impact of the extra phase lag from the RHP zero. Some regulators feature external loop compensation components. These devices allow the designer much more flexibility in setting the loop gain crossover frequency and tailoring the loop response.