A detector circuit for detecting a phase or frequency error of an input signal. One mode of at least two detection modes is selected according to a phase or a frequency of the input signal with each mode having a reference value of a phase or a frequency of the input signal and reference values of the detection modes being different from each other. A pulse signal having a phase corresponding to a difference between an actual phase or frequency of the input signal and the reference value of the phase or the frequency is generated, and a predetermined carrier signal is pulse width modulated with a predetermined modulation factor in response to the pulse signal, the modulation factor being different for each detection mode.