Actually you didn't understand my problem correctly. 

In charge solver when we give voltage a sudden change in carrier concentration occurs and the carrier concentration will reach the peak value only after a certain period (rise time) and inorder to measure rise time we need to give a step voltage which is a function of time and in charge solver the only option available to give step voltage in such a manner is through transient simulation. The purpose of transient simulation is to study the systems behaviour over time.

In charge, transient method is available that is why i asked doubt regarding that and you told using the transient option  in charge it is not possible to get continuously varying voltage.

Thank you for your reply.

Also we have a licence for all the ansys solvers including interconnect and from interconnect it is only possible to get the eye diagram and not the rise time that is why i request you to suggest any other method.