Coprime arrays offer degrees of freedom of O(MN) given O(M+N) sensors, where M and N are coprime integers. The performance of coprime arrays is based on coprime DFT filter banks (coprime DFTFBs), which cascade an M-channel DFTFB and an N-channel DFTFB to achieve MN-channel filter banks. However, practical designs of coprime DFTFBs have not been fully studied. In this paper, a systematic design is related to IFIR filter designs, based on M, N, filter orders, and peak ripples. Our design owns a parameter λ that provides tradeoffs between passbands and stopbands. A design example for different λ is also presented1.