The ARF should meet the specifications shown in the following table. The input and output sample rates imply the fractional interpolation ratio can be any real number between 1.4286 and 2.0. There can be up to K = 2 samples computed from every new input.
Parameter | Value |
---|---|
Range of input sample rate | 250–350 MSPS |
Output sample rate | Fixed at 500 MSPS and synchronous to the output clock |
Interpolation ratio adjustment step | 1/2^{30} |
Number of taps (L) | 16 |
Input/output data format | 16-bit I + 16-bit Q |
Filter coefficient bitwidth | 16-bit |
First-in-first-out latency | Fixed at 1 μs (exactly 500 clock cycles in the output clock domain) |
The ARF input sample rate is nominal and does not necessarily match the clock frequency of PL logic. Many baseband units process data in bursts, leading to a large fluctuation in the instantaneous input sample rate. Nevertheless, the ARF output should be a continuous data stream, synchronous to the output clock.