about vhdl code for cic interpolation filter

and where did you attach the doc to?

I tried my luck numbers and here I managed to get expected values:

Bin = 8; %input width

N = 4; %stages of comb or integrator

M = 2; %differential delay

R = 512; %interpolation rate

%cic decimator at any stage

Bout = N * log2(R*M) + Bin;

%cic interpolator per ith stage

%stages 1~N

for i = 1:N

G = 2^i;

Bout = Bin + log2(G);

d(i) = Bout;

end

%N+1 ~ 2N stages

for i = N+1:N*2

G = 2^(2*N-1)*(R*M)^(i-N)/R;

Bout = Bin + log2(G) - i + 1;

d(i) = Bout;

end

for i = 1:N*2

fprintf('%i %i\r',i,d(i));

end