I have a DAC ( driven by a 89c51 )generating a ramp at the rate of 1 bit ( 50mV ) every 50 millisecond. This when viewed on a reasonably fast plot on PC ( via a high speed PCI DAS card ) shows up as staircase. I would like to add a low pass filter to convert this staircase into a smooth ramp.

Can I get the required steps to calculate the required R & C values and the setup ? ( If I can do without Inductors its fine - hope I can )

I did search the forum and there are some discussions on software filters and FIR stuff. I am looking for a hardware solution.

I remember that this was similiar to a discussion on smoothing a PWM output - somehow I am unable to latch on to the right thread...

Any help is appreciated. I am looking for the general guidelines to work out the solution in such cases - I don't want the fish - but looking to learn fishing ;-)

Thanks

Raghu