A frequency-voltage converting circuit 13 is composed of a switch unit including switches SW1 and SW2, electrostatic capacitive elements C and C10 to C13, and switches CSW0 to CSW3. The electrostatic capacitive elements C10 to C13 are composed of elements having mutually different absolute values of capacitance and are provided so as to cover a frequency range intended by a designer. The electrostatic capacitance values are weighted by, for example, 2. The electrostatic capacitive elements C11 to C13 are selected by, for example, the switches CSW0 to CSW3 based on 4-bit frequency adjustment control signals SELC0 to SELC3, thereby carrying out frequency switching.