A semiconductor integrated circuit includes a clock recovery circuit that receive a multi-level pulse-amplitude modulated signal and to recover a clock signal. The clock recovery circuit includes a generation circuit and an oscillator. The generation circuit includes a plurality of comparators and pulse generators and a pulse summing circuit. The plurality of comparators and pulse generators compare the multi-level pulse-amplitude modulated signal with a plurality of threshold values to generate a plurality of pulses according to a plurality of comparison results. The pulse summing circuit generates a synthetic pulse based on the generated plurality of pulses. The oscillator oscillates in synchronization with the synthetic pulse to generate the clock signal.