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The quoted paper doesn't explain the bit growth exactly, neither for decimation nor interpolation filters. Besides the Matlab tool, I would always refer to the original Hogenauer paper introducing CIC filters. Bit growth in the comb section of interploation filters is in fact simple, one bit per stage.
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Thanks FvM.
I assume the equations for bit growth given in attached doc look too involved to be wrongly typed from original source(Hogenauer's).
But I did notice discrepancy of last equation when applied to i = N as Bout = Bin + N -1
Anyway do you have access to Hogenauer's doc? or do you know where those given equations go wrong.
I know Hogenauer also included method for register pruning to reduce bit growth by distributing quantisation noise across stages. Naturally too involved and too specialised corner and may be unwarranted with FPGAs applications.
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