An integrated circuit includes a signal generating unit, a signal monitoring unit and a processing unit. The signal generating unit is configured to generate a control signal. The signal monitoring unit is configured to receive the control signal and accordingly output a monitor signal. The processing unit is configured to receive the monitor signal. The control signal is adjusted until the monitor signal is located within a preset range. A signal monitoring method used with the integrated circuit and a signal monitoring method used with a plurality of transistors are also provided.