How to generate a staircase waveform with the edges SMOOTHENED ?

[biswa263]

But since I am using the block as a low pass filter and so I should be specifying only the upper cut off frequency....isn't it?

[LocalDSP]

Low cut-off is used for lowpass and highpass filters where you only need to specify a single frequency value. High cut-off is ignored.

Both low and high cut-off are used to define bandpass and bandstop filters.