This paper presents an energy harvester circuit in a $\mathbf{0.18}-\mu\mathbf{m}$ CMOS process. The clock booster is employed to increase the amplitudes of the pulses and easily turn on the buck-boost converter. The proposed technique provides a stable power supply without using a low dropout regulator. The simulation results show the output voltage about 841 mV with the input frequency of 100 kHz, the peak-to-peak voltage of 1.6 V, a load capacitance of 10 nF, and a load resistance of $\mathbf{10}\ \mathbf{G}\Omega$, respectively. Fully powered by a vibration piezoelectric energy harvester (PEH), the proposed circuit consumes an average power of $\mathbf{114}\ \mu \mathbf{W}$.