Electronic devices converting input signals to digital values and operating methods of electronic devices

An electronic device which may include an analog-to-digital converter circuit that converts a level of an input signal to digital input values in response to a clock signal, an oscillator that generates the clock signal, a first equalization circuit that generates digital output signals by equalizing the digital input values, a first phase detector circuit that detects phases of the digital output signals and generates digital phase values, a loop filter that generates a first digital output value based on the digital phase values, a second equalization circuit that generates digital intermediate values by equalizing the digital input values, and a second phase detector circuit that detects phases of the digital intermediate values and generates a second digital output value. The oscillator may adjust a frequency of the clock signal based on the first digital output value and the second digital output value.