Method and apparatus for load adaptive LDO bias and compensation

摘要

An adaptive low dropout (LDO) regulator includes a load-based bias controller that generates a bias control signal based on the output load current, and has a differential amplifier with a bias adjustment that receives the bias control signal and responds by adjusting a bias of a transistor within the adaptive LOD regulator. Optionally, the bias control signal is generated according to a hysteresis rule. Optionally, the adaptive LOD regulator includes an adaptive load-based compensation network having a zero, the zero having a location based, at least in part, one more of an adjustable resistance or capacitance value controlled by the load-based bias controller.

主权项

1. An adaptive low dropout (LDO) regulator comprising:
a pass gate, having a pass gate output and having a control input for receiving a pass gate control signal, wherein the pass gate is configured to provide, for a load current, a variable resistance current path from an external power rail to the pass gate output, at a resistance based, at least in part, on the pass gate control signal, and to output the load current from the pass gate output; a load-based bias controller circuit, configured to generate a load-based bias control signal at a value that corresponds to the load current, wherein the load-based bias control signal switches from a first bias control level to a second bias control level in response to the load current increasing past a threshold and switches from the second bias control level to the first bias control level in response to the load current decreasing from a level that is above the threshold to a level that is less than the threshold; an adaptive bias differential amplifier, having a first input, a second input and a transistor, wherein the first input is coupled to the pass gate output, and the transistor has a gate coupled to the first input or to the second input, wherein the adaptive bias differential amplifier is configured to receive the load-based bias control signal with a bias current, the bias current being, in response to the first bias control level of the load-based bias control signal, a light load bias current and, in response to the second bias control level of the load-based bias control signal, being a heavy load bias current, wherein the light load bias current is higher than the heavy load bias current, and wherein the adaptive bias differential amplifier is further configured to generate the pass gate control signal based on voltages received on the first input and the second input.