Well the best way to convert a PDF file to DWG or dxf, if the file was generated with a vector application (CAD) cool, using importing the file could be a good solution, however I've been in this situation before and I can tell you this:
If for some reason you have access to Adobe Illustrator import the PDF to Illustrator then from the file menu I think you can export or save as a DWG. I do not remember which of the 2 commands but Im 100% sure that it will be a big surprise for you, like it was for me in the past.
Adobe Illustrator is a powerful vector software similar to Corel Draw, etc and because of this you can export to dwg!!!
I've already answered your question in the AutoCAD forum.
I use online an conversions to produce dwg or dwf. As mentioned previously the PDF file that you're converting must contain vector graphics in order to produce decent results. Conversions can be done at:
There 2 fundamental definitions when you work images and CAD software: The first thing is that images are a result of a computational process that, as a result, get every single bit of information that comprises the image get to store as small dots, pixels.
Lets analyse something: Lets say you scan a picture of the size (in inches) 5x7 in; you put inside photoshop with a canvas 8x11 inches big. If you stretch the image the image will distort Why? Supouse there is to pixels 1 red the other blue, before you stretch the image they are one close to the other, after you stretch the image you will notice that between the 2 pixels now are 5 pixels (depending on the new size of the image of course) , and that is the origin of the distortion of any image.
That happened because the computer will try to FILL the gap between the 2 pixels with other pixels that may be are in the same tone of colours
like a gradient/transition from one colour to the other.
Now Vectors (CAD Software) : Vectors are a result of mathematical calculations, lines and curves hat are generated on the screen from one point to another and because of this vector will never get distort after an stretch/zoom operation, Because vector graphics are not made of pixels, the images can be scaled to be very large without losing quality. Raster graphics, on the other hand, become "blocky," since each pixel increases in size as the image is made larger. This is why logos and other designs are typically created in vector format.
To conclude if your intention is convert images to vectors use Adobe Illustrator/Corel Draw these soft has the capabilities of conversion however do not think that is just press the button "Apply", you will have to work a bit to get the result that you expect, You can also use AutoCAD Raster Design for this matter