An Efficient Waveform Reconstruction Method for Digital Bandwidth Interleaving Sampling System

Digital bandwidth interleaving (DBI) technology is a method that can simultaneously improve the bandwidth and sampling rate of a sampling system. However, its waveform reconstruction algorithm is very complex, and the realization of real-time waveform reconstruction requires a great number of system parallel computing resources. This article proposes a frequency-domain waveform reconstruction method for a DBI sampling system to improve the waveform reconstruction efficiency. This method completes digital mixing, filtering, and corrections in the frequency domain and recovers the waveform from the discrete frequency-domain information. This method takes advantage of the computational efficiency advantages of the frequency-domain filtering method compared with the time-domain filtering. Also, it integrates multiple time-domain filter coefficients in the DBI system into a frequency response coefficient, so that one frequency-domain filtering is equivalent to multiple time-domain filtering operations. This article also introduces a polyphase frequency-domain filtering structure, which has great advantages in computational complexity compared with the classical time-domain parallel polyphase filtering structure. To verify the efficiency of the method, an evaluation platform with 8-GHz bandwidth and 20-GSPS sampling rate is implemented to illustrate its performance. Both the classical time-domain method and the proposed frequency-domain method are verified in MATLAB and are compared for performance and resource consumption in FPGA. Experimental results show that the proposed method saves 10% lookup tables (LUTs), 26% flip-flops (FFs), and 47% digital signal processing (DSP) slices compared with the classical time-domain method. Under the condition that the word length is less than 6 bits, the proposed method improves the SFDR by more than 5 dB and SNR by more than 10 dB compared with the classical method.