Psemi Corporation

Satish Vangara

Carlos Zamarreno Ramos

Circuits and methods for maintaining loop stability and good load regulation in low loop gain LDO regulator circuits. Embodiments encompass LDO regulator circuits that include an offset error correction circuit that generates an opposing voltage Vas a function of load current to substantially cancel out variations in Vthat would otherwise occur due to load regulation limitations of the LDO regulator circuits. Embodiments use Vto imbalance currents in differential paths in a last-stage LDO error-amplifier so that an offset is propagated to a pair of inputs to the error-amplifier, thereby altering the output voltage Vto a corrected value. Benefits include improved LDO load regulation even when feedback loop gain is low, the available of both digital and analog implementations, high LDO accuracy and less variation of the output voltage V, and suitability for implementation in integrated circuits for applications such as high precision power supplies.

Load regulation for LDO with low loop gain

Circuits and methods that provide for fast power up and power down times in a multi-stage LDO regulator. In one embodiment, a multi-stage LDO regulator circuit includes, for each stage for which fast power up and/or power down times are desired, at least one transconductance amplifier coupled and configured to compare a primary reference voltage to one of a secondary reference voltage for the stage or an output voltage of the stage, and coupling and configuring the at least one transconductance amplifier to charge and/or discharge an associated capacitor to achieve a desired charge level within a specified time independently of the value of the associated capacitor. In general, the transconductance amplifiers of each stage are configured to charge and/or discharge an associated capacitor in synchronism with a voltage present on the primary reference voltage input.

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San Diego, CA, United States of America

Satish Vangara