Pole-zero tracking compensation network for voltage regulators

Abstract

Compensation circuits, compensated voltage regulators, and methods are provided for stabilizing voltage regulators, or other circuits that use operational amplifiers, over a wide range of output current. The described techniques provide a zero whose frequency varies linearly with an output current, and which can be used to track and compensate for a pole whose frequency similarly varies with the output current. The variable-frequency zero is created using a compensation capacitor placed in series with a variable resistance, wherein the resistance is configured to vary linearly with the output current. A pole-tracking zero generated in this way may be used to overcome difficulties encountered when the gain of a system includes a pole whose frequency varies with output current, and serves to improve the phase margin of amplifier circuitry, including that used within voltage regulators, and/or serves to ensure stability over a wide range of output current.