This paper presents a wide range high efficiency fully integrated switched-capacitor DC-DC converter with fixed output spectrum targeting for noise-sensitive Internet-of-Things (IoT) applications. In order to alleviate the unpredictable output spectrum and the reduced energy efficiency of the conventional pulse-frequency modulation (PFM) and pulse-width modulation (PWM) schemes, fixed output spectrum (FOS) modulation is proposed to ensure easy noise filtering while achieving wide range high efficiency operation. A 2-phase 3-level gate driver is also proposed to minimize the reversion loss and enhance conduction. Simulation result in a standard 0.18-μm CMOS process shows that up to 88% high energy efficiency can be achieved with a loading range from 75μA to 3mA using a total flying capacitance of 0.96nF.