A regulating circuit is configured to adjust current consumptions. The regulating circuit comprises a switch and at least two matching circuits. The at least two matching circuits are configured to match different input signals and reduce current consumptions. The switch is coupled to the at least two matching circuits. According to different input signals, the switch switches on one matching circuit and switches the other matching circuits off. Each matching circuit comprises a transmission line and a varactor. The transmission line is coupled to the switch. The transmission line is configured to adjust a phase angle in a Smith chart quadrant. The varactor is configured to further adjust the phase angle. Thus the phase angle is adjusted to a predetermined position in the certain quadrant. An optimizing circuit is also provided. In the present disclosure, different input signals can be transmitted in a corresponding matching circuit to optimize current consumptions.