The present disclosure discloses a band-pass analog-to-digital converter (ADC) using a bidirectional voltage-controlled oscillator (VCO) including a first converter configured to receive an analog input signal and quantize the analog input signal according to a first clock signal to output a first digital signal, a second converter configured to receive the analog input signal and quantize the analog input signal in a time-interleaving manner according to a second clock signal, which has a phase opposite to that of the first clock signal, to output a second digital signal, and a multiplexer configured to receive the first and second digital signals and select one of the two signals in response to the first clock signal to finally output a digital output signal.