Does a planted aquarium doesn't need filter at all?

Theoretically you do not need a filter in a planted tank. I have a 40g with a small 5-15 aqua tech for circulating the water a little more. I have removed the carbon from the cartridge as well, as to not remove the nutrients the plants need. The filter is good at removing some of the larger floating debris as well. Keep testing your water for nitrate levels as you go along to help judge whether a filter is needed for your tank. I should add that the amount of fish is a consideration as to the amount of waste the tank will have to convert...