Abstract: Exemplary embodiments may disclose a flip-flop circuit for inserting a zero-delay bypass mux including a master circuit which is configured to receive a data input, an input clock signal, and a bypass signal, and output an intermediate signal to a first node; and a slave circuit which is configured to receive the intermediate signal at the first node, the input clock signal, and the bypass signal, and output an output clock signal. The bypass signal controls the slave circuit to output one of a buffered input clock signal and a stretched clock signal as the output clock signal based on a logic level of the bypass signal.