An analog-to-digital conversion circuit includes analog-to-digital converters (ADCs) including a target analog-to-digital converter (ADC) providing second data samples, a first adjacent ADC providing first data samples, and a second adjacent ADC providing third data samples. The ADCs perform an analog-to-digital conversion using a time-interleaving approach in response to clock signals having different phases and including a reference clock signal. A timing calibration circuit includes a relative time skew generator generating a relative time skew and an absolute time skew generator generate an absolute time skew. A clock generator adjusts at least one phase of the clock signals based on the absolute time skew.