An integrated circuit for providing an output voltage substantially equal to a reference voltage includes: a low drop-out (LDO) regulator coupled to the reference voltage for producing the output voltage at an output terminal; a fast turn-on circuit coupled to the LDO regulator for quickly supplying an output current at the output terminal according to a first control signal; and a fast turn-off circuit coupled to the LDO regulator for quickly drawing a discharge current from the output terminal according to a second control signal.