LAUSR

A partial analogue-assisted (AA) digital low dropout regulator (D-LDO) with also a transient body-drive (BD) technique is proposed. The body of the power switches can be driven by the V OUT transient spike that is high-pass coupled from the D-LDO output when a load step occurs, for a temporary threshold voltage change. The BD technique thereby manages to provide more than 10% momentary output current. In addition, since the effectiveness of the AA loop is proportional to the ratio of the coupling capacitance and the parasitic capacitance, here, only about 1/5 of the most significant bit of the power switches are connected to the AA and BD networks. Therefore, the coupling capacitors are much reduced, comparing to the previous work. A simulated 100 mV undershoot is obtained under a 2-to-12 mA load step within 1 ns edge time, using only 40 pF total capacitor. A 0.09 ps figure-of-merit (FOM) of speed is thereby achieved, which is at least 2.5× better than state-of-the-art works.