Design Specifications

Arbitrary Resampling Filter Design (XAPP1373)

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1.0 English

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.

Table 1. Arbitrary Resampling Filter Design Specification
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 1/230
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.