Parameters: I: Height of step response source current after infinite time (default value = 1 Amp) riseTime: Rise time of step response to be generated (default value = 0.5 sec) riseTimeConst: Rise time constant of step response to be generated (default value = 0.1) fallTimeConst: Fall time constant of step response to be generated (default value = riseTimeConst) offset: Offset of step response to be generated (default value = 0 Amp) startTime: Start time of step response to be generated (default value = 0 sec)