High Bandwidth Constant On-Time PWM Control

Apparatus and associated methods relate to dynamic bandwidth control of a variable frequency modulation circuit by selective contribution of a crossover frequency tuning engine (XFTE) in response to a transient in a switching frequency. In an illustrative example, the XFTE may generate a transient control signal (Ctrans) in response to a transient in a control output signal (Cout) indicative of switching frequency and received from a feedback control circuit. The XFTE may generate Ctrans, for example, according to a predetermined relationship between a crossover frequency and the switching frequency of the modulation circuit. The feedback control circuit may, for example, generate Cout from a predetermined reference and a control input signal. Cout may, for example, correspond to a pulse-width modulated output delivered to a load through an inductor. Various embodiments may advantageously increase the effective bandwidth of the modulation circuit while maintaining desired frequency response characteristics.