HLS Implementation of a Flexible Resampling Filter Using Chirp-Z Transform With Overlap-Add

Abstract

A possible way of increasing the resolution with which the bandwidth of a system can be selected is by using a flexible resampling filter. Such a filter, using overlap-add (OA) and chirp-Z transform (CZT), is suggested and implemented with Vivado highlevel synthesis (HLS) on a field-programmable gate array (FPGA). The resulting filter can handle flexible resampling by varying the input length from 37 to 87 samples while constantly outputing 32 samples. To evaluate this implementation, a reference case was also created, using OA with a regular fast Fourier transform (FFT). When comparing the two cases, it was found that the flexibility that was granted by the CZT implementation utilizes almost 4 times more digital signal processing (DSP) slices in the target FPGA. However, the throughput of the CZT implementation is 36 % higher. Finally, it is concluded that a flexible buffer will be needed to change the resampling ratio during runtime and a possible implementation in hardware is suggested.