A PWM buck converter includes a first P-type transistor having a drain terminal connected to a first node, a first N-type transistor having a drain terminal connected to the first node, and a gate driver configured to apply a first gate voltage to a first gate terminal of the first P-type transistor and apply a second gate voltage to a second gate terminal of the first N-type transistor. The gate driver includes a first buffer configured to generate the first gate voltage applied to the gate terminal of the first P-type transistor, a second buffer configured to generate the second gate voltage applied to the gate terminal of the first N-type transistor, and a capacitor configured to accumulate a portion of electrical charges supplied from the first buffer to the first P-type transistor, and supply the accumulated electrical charges to the gate terminal of the first N-type transistor.