This paper presents the modeling of linear-assisted DC-DC regulators. This kind of voltage regulators consists of a switching converter together with a classic or LDO (low dropout) linear voltage regulator. While the linear regulator provides the constant output voltage, the switching converter conducts nearly all the current provided in the output load, and keeping the regulator current close to zero where the higher efficiency is achieved. However, the circuit could be unstable due to some critical parameters such as parasitic output capacitance; as a consequence, the mathematical modeling is obtained to study and corroborate the stability of the whole system.

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