This Mixed Signal Letter presents a proposal of four-quadrant linear-assisted DC/DC voltage regulator. In this topology, a class-AB linear voltage amplifier assists a four-quadrant switching DC/DC converter in order to obtain a compact circuit with advantages of both alternatives; i.e., high efficiency, inherent in switching converters, and low output ripple and fast reaction to the load changes that are characteristics of linear regulators. In order to reduce the power dissipation in the linear regulator, it is considered as an assisting circuit for providing just a small fraction of the total load current. Furthermore, this stage provides the required clock signal for the switching counterpart, obtaining a compact topology thanks to the reduction of the complexity in the design of the control scheme for the switching converter. In fact, the proposed topology can be addressed to on-chip practical implementations, since no output capacitors are required. This last advantage provides the possibility of obtaining good-performance power-supply modulators for envelope tracking techniques in power amplifiers. The implementation and results indicate that the proposed four-quadrant linear-assisted DC/DC regulator can achieve a notably compacting and higher performance, while consuming less power in comparison to linear alternatives.