is there any good method to do this?
Make an auger, (see below) and scale to suit.
Delete the sections you don't want.
Extrude it's ends to provide entry/exit platforms.
Extrude all vertices down in the Z axis for thickness if necessary.
(the cylinder at center is optional)
Auger Blade - -========-
Add a Curve path, leave it a, straight line.
Add the "Screw" modifier. The bezier will turn into a solid disc.
Increase the "Screw" slider to watch the Auger forming up.
Increase the "steps" to improve the circumference curvature.
Use ATL-C in Object mode to convert it to mesh.
You could create a 90-degree angle and use a subdivision surface set to around 2 or 3. Then click smooth in the left panel. This should create a smooth enough curve. You can use loop cuts to straighten out parts you don't want curved.
I have a feeling you're looking for something that may not be geometrically possible (a smooth continuously sloping ramp like you are describing can't be made out of a small number of simple tris/coplanar quads). The answers given so far have provided some pretty good options within the constraints of what can be done. Here is one more option:
You might call this a variation on some of the answers already given. This was created by making a helical "screw augur" as described in @Edgel3D's answer and then slicing it into a square shape using boolean modifiers with cube objects as the cutters, one for the exterior and one for the interior.
When the augur helix is sliced up this way, the exterior and interior edges are a bit "wavy", they do not describe straight lines but rather slight sine curves. They can be straightened, although this is a bit tedious: the vertices along each edge have to be manually aligned to a line using a custom transform orientation, using the technique described in @Mentalist's answer to this question:
The resulting shape is a bit curious, it is composed of quadrilaterals whose vertices are not quite coplanar. But the end result is a ramp where the distortions are spread out and therefore more or less "smooth", rather than confined to the corners of the ramp.