How can I generate this repeating pulse?

I want to generate a pulse that repeats this voltage pulse at cadence virtuoso schematic. (Fig.1)

                                             (Fig.1 I want to generate a pulse that repeats this voltage pulse.)

However, I do not know yet how to generate a pulse that repeats the voltage pulse in Fig.1

How can I do this?

Please tell me.

Thank you 

yysunj