A voltage controlled oscillator (VCO) includes a VCO unit having multiple VCO unit output terminals and an amplifier having multiple amplifier output terminals respectively connected to the VCO unit output terminals. The VCO unit generates first output signals having an oscillation frequency corresponding to a supply voltage. The amplifier amplifies a value obtained by performing n-th differentiation on a transconductance component of each first output signal (n being a natural number). Second output signals, corresponding to the first output signals, are output through the amplifier output terminals. Each second output signal includes the amplified value of the corresponding first output signal.