Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Efficient implementation of 90° phase shifter in FPGA | Duraiswamy et al. EURASIP Journal on Advances in Signal Processing 2011 2011 32 http content 2011 1 32 o EURASIP Journal on Advances in Signal Processing a SpringerOpen Journal RESEARCH Open Access Efficient implementation of 90 phase shifter in FPGA Punithavathi Duraiswamy Johan Bauwelinck and Jan Vandewege Abstract In this article we present an efficient way of implementing 90 phase shifter using Hilbert transformer with canonic signed digit CSD coefficients in FPGA. It is implemented using 27-tap symmetric finite impulse response FIR filter. Representing the filter coefficients by CSD eliminates the need for multipliers and the filter is implemented using shifters and adders subtractors. The simulated results for the frequency response of the Hilbert transformer with infinite precision coefficients and CSD coefficients agree with each other. The proposed architecture requires less hardware as one adder is saved for the realization of every negative coefficient compared to convectional CSD FIR filter implementation. Also it offers a high accuracy of phase shift. Introduction Phase shifters have wide spread applications 1-3 in particular 90 phase shifters are used in wireless communication for single side band generation IQ modulation and image rejection. Digital implementation of 90 phase shifters is in high demand as many of the digital communication systems use FPGAs 4-6 . The FPGAs offer a wide range of performance for implementing DSP algorithms and hence it is important to efficiently map the algorithm in order to optimize the area and speed. Hilbert transformer is the most widely used 90 phase shifter implemented either by a finite impulse response FIR 7-9 or by an infinite impulse response IIR filter 10 . Since the Hilbert transformer is required to shift the phase by 90 over a wide range of frequencies FIR filter with linear phase is preferred over IIR filter. The conventional method of implementing the FIR filter is by adders .
