Frequency measurement circuit and frequency measurement apparatus

A frequency measurement circuit comprising:

• an oscillation circuit that generates a reference clock signal;
• a first counter that counts a pulse number of the reference clock signal and generates first count data;
• a second counter that counts a pulse number of a measurement target clock signal and generates second count data;
• a time-to-digital conversion circuit that generates first time difference data indicating a time difference between a first timing at which the first counter starts counting of the pulse number of the reference clock signal and a second timing at which the second counter starts counting of the pulse number of the measurement target clock signal, and second time difference data indicating a time difference between a third timing at which the first counter ends counting of the pulse number of the reference clock signal and a fourth timing at which the second counter ends counting of the pulse number of the measurement target clock signal;
• and
• a calculation circuit that performs calculation based on the second count data, the first time difference data, and the second time difference data and generates frequency data indicating a frequency of the measurement target clock signal.