A Down-Sample Design under Special Condition in High-Speed All-Digital System

Digitalization and high-speed signal processing is the trend of electronic information and technology. In order to avoid unnecessary calculation, the sampled data in high-speed digital system have to be down-sampled. Three designs of down-sample are discussed and compared with each other in this paper so that people choose the most suitable plan in different works. One with FIR filters is a classical design and is applied widely. The other is an unfamiliar design which is applied directly to band-pass signal. Another is the CIC decimation filter design which is used in recent years. Specially, the theory and design technique of cascaded integrator-comb (CIC) filter cascaded interpolated second-order polynomial (ISOP) filter are analyzed. Simulation is done to validate the usefulness of compensating attenuation in pass-band of ISOP filter on CIC filter. The conclusion is that the system employs CIC decimation filter shows advantage over the other two plans in appliance and reserving resources. A combined down-sample design that can reduce the complexity of the entire system effectively is put forward based on the three designs above in the end.