Provided is a low voltage frequency synthesizer using a boosting method for a power supply voltage of a charge pump. The low voltage frequency synthesizer includes a phase/frequency detector (PFD) that receives and compares a reference frequency and a feedback frequency to output a comparison signal, a charge pump that receives the comparison signal to output a current corresponding to the comparison signal, a low-pass filter (LPF) that generates a voltage corresponding to the output current of the charge pump, a voltage controlled oscillator (VCO) that receives the voltage of the LPF, amplifies the voltage to generate a boosting voltage, and outputs a frequency corresponding to the received voltage, and a DC converter that receives the boosting voltage of the VCO, converts the boosting voltage into a DC voltage, and applies the DC voltage as a power supply voltage of the charge pump. Since the supply voltage of the charge pump is provided from the LC-circuit-based VCO, the frequency synthesizer has superior characteristics such as a wide locking range, low phase noise, and the prevention of performance degradation caused by an external environment or process variations.