A circuit device includes a waveform-shaping circuit that waveform-shapes an oscillation signal and provides an output clock signal based on a clock signal. A bias voltage output circuit of the circuit device provides a bias voltage of the oscillation signal that is input to the waveform-shaping circuit. A comparator of the circuit device compares a DC voltage obtained by smoothing the clock signal with a reference voltage. A logic circuit of the circuit device sets an adjustment value of the bias voltage. In a test mode of the logic circuit, the logic circuit changes the adjustment value to determine a set value of the adjustment value based on output of the comparator when the adjustment value is changed and stores the determined set value in a storage circuit.