A flip-flop circuit includes a first latch, a second latch and a trigger circuit. The first latch is configured to set a first output signal based on a first input signal and a clock signal. The second latch is configured to set a second output signal based on a second input signal and the clock signal. The trigger circuit is coupled with the first latch and the second latch. The trigger circuit is configured to generate the second input signal based on at least the second output signal. The trigger circuit is configured to cause the second input signal to have different voltage swings based on the first output signal and the second output signal. The trigger circuit includes a logic circuit coupled to at least the first latch or the second latch. The logic circuit is configured to output the second output signal.