Semiconductor device, signal processing device, and control method of signal processing device

A signal processing device comprising:

• an oscillation circuit configured to receive a frequency control signal and generate a clock signal whose frequency is variable based on the frequency control signal,
• a protection target circuit configured to operate based on the clock signal,
• a delay time detection circuit including a test circuit corresponding to a configuration of a predetermined circuit in the protection target circuit, the delay time detection circuit being configured to detect a delay time of a signal generated in the test circuit and output a delay amount detection signal based on the delay time, and
• a clock control circuit provided external of the protection target circuit, the clock control circuit being configured to receive the delay amount detection signal and generate the frequency control signal,
• wherein the frequency control signal for declining the frequency of the clock signal in response to an increase in the delay time.