My system uses a CIC interpolation (6X) filter.
Binary input is fed thru a rcos matched filter with OVS=10, passband BW is 
B,
resulting in data D1, which is subsequently interpolated by CIC to 6X times.

The amplitude of interpolated output (D2) is lower than matched filter 
output,
which can be explained by the non-uniform gain in the CIC filter. The gain 
at B is
5dB lower than gain near 0 Hz (gain f = 0Hz is undefined).

I need to calculate the amplitude ratio of D2 theoretically so that I put in 
document.

Thanks in advance!