Method and apparatus for maintaining stability in a circuit under variable load conditions

摘要

A circuit (10) having multiple poles within an active frequency range employs a movable zero (66) to maintain stability in the circuit (10) under variable load conditions. A pole (62) created by a frequency compensation element (14) maintains a fixed frequency within the active frequency range of the circuit (10). In addition, a variable load impedance (36) coupled to the circuit (10) generates a load pole (64) within the active frequency range of the circuit (10) that changes frequency over time. As the load pole (64) changes frequency, the frequency of the movable zero (66) is adjusted to achieve an enhanced stability condition within the circuit (10). In one embodiment, the frequency of the movable zero (66) tracks the frequency of the load pole (64) as the load impedance (36) changes.