# DFT Polyphase Filter bank

What is the purpose of DFT & IDFT blocks which are placed after the Analysis filter bank & before the Synthesis filter bank. The reason i am asking this question is because I tried to design Polyphase DFT filter bank & got the same output with & without DFT-IDFT block.

• what is the major difference between th dft and polyphase dft with contrast of improving resolution and what is the size of dft for n point polyphase 2,4 and 8. – kranthi kumar Jul 9 '15 at 13:32
• This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient reputation you will be able to comment on any post. – MBaz Jul 9 '15 at 14:02

• Each DFT bin corresponds to 1 sub-band, so with an $M$-point DFT you have $M$ sub-bands. – Matt L. Jun 24 '13 at 9:14