If you are talking about generating a ramp at a given frequency, then you will have a capacitor in the feedback loop of an op amp, forming an integrator. Capacitance is defined as the ratio of charge to voltage or the change in charge for a change in voltage. C=Q/V=dQ/dV=IdT/dV where I is related to R and the time differential is related to frequency. Just how these are related depends on your circuit.
If you are talking about filtering a ramp signal, or filtering a pulse train, then you will need to be more specific about what the filtering is intended to accomplish.
