Browsing by Author "Cintra, RJ"

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    item: Conference-Abstract
    Design methodology of an analog 9-beam squint-free wideband IF multi-beamformer for mmW applications
    (2017) Ariyarathna, V; Udayanga, N; Madanayake, A; Perera, SM; Belostotski, L; Cintra, RJ
    An intermediate frequency (IF) squinting-free multi-beamforming method is proposed for multi-antenna systems. The proposed approach uses a low-complexity factorization of a true-time-delay (TTD) multi-beam matrix, which is proposed to be realized using an analog integrated circuits approach. A TTD realization of multi-beams at intermediate frequency is achieved following amplification and synchronous down-conversion via the proposed Delay Vandermonde Matrix (DVM) in which matrix elements correspond to the compound phase compensation required for squint-free steering of each radio-frequency beam. True-time-delays are proposed to be efficiently realized on-chip by applying a sparse factorization to the DVM, which leads to a low circuit complexity implementation requiring a significantly lower number of TTD blocks and phase compensations compared to an equivalent direct implementation for a given N number of beams. The proposed method, for 9- beams, leads to a 60% reduction of analog integrated circuit based TTD blocks and phase compensators. The TTD blocks can be realized on chip using active-RC based integrated analog all-pass filters. The proposed multi-beam algorithm and circuit structure is simulated within the frequency range 55-65 GHz to demonstrate squinting-free wide-band multi-beams at millimeter wave carrier frequencies for emerging 5G applications.
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    item: Conference-Abstract
    Multi-beam 8 × 8 RF aperture digital beamformers using mMultiplierless 2-D FFT appro ximations
    Kulasekera, S; Madanayake, A; Wijenayake, C; Bayer, FM; Suarez, D; Cintra, RJ
    The two-dimensional (2-D) discrete Fourier transform (DFT) is widely used in digital signal processing (DSP) and computing applications. Fast Fourier transforms (FFTs) are widely used as low-complexity algorithms for the computation of the DFT as it reduces the required computation operations from O(N2) to O(N log2 N). The multiplicative complexity is used as a benchmark in comparing different algorithms as it affects the circuit complexity, chip area and power. This paper introduces a new class of multiplierless hardware algorithm consisting only of arithmetic adder circuits that closely approximates the 2-D version of the 8-point DFT. The paper discusses the theory behind the proposed new algorithm, with the DFT presented in the form of an 8 × 8 matrix. Furthermore it provide a multi-beam RF aperture application example where the 2-D DFT approximation has been used to closely obtain the antenna array patterns.
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    item: Conference-Full-text
    Multi-Beam 8 × 8 RF Aperture Digital Beamformers Using Multiplierless 2-D FFT Approximations
    (2015-08-03) Kulasekera, S; Madanayake, A; Wijenayake, C; Bayer, FM; Cintra, RJ
    The two-dimensional (2-D) discrete Fourier transform (DFT) is widely used in digital signal processing (DSP) and computing applications. Fast Fourier transforms (FFTs) are widely used as low-complexity algorithms for the computation of the DFT as it reduces the required computation operations from O(N2) to O(N log2 N). The multiplicative complexity is used as a benchmark in comparing different algorithms as it affects the circuit complexity, chip area and power. This paper introduces a new class of multiplierless hardware algorithm consisting only of arithmetic adder circuits that closely approximates the 2-D version of the 8-point DFT. The paper discusses the theory behind the proposed new algorithm, with the DFT presented in the form of an 8 × 8 matrix. Furthermore it provide a multi-beam RF aperture application example where the 2-D DFT approximation has been used to closely obtain the antenna array patterns.
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    item: Conference-Full-text
    Real-time 2-d fir trapezoidal digital filters for 2.4 ghz aperture receiver applications
    (IEEE, 2018-05) Ariyarathna, V; Coutinho, VA; Pulipati, S; Madanayake, A; Wijesekara, RT; Edussooriya, CUS; Bruton, LT; Gunaratne, TK; Cintra, RJ; Chathuranga, D
    This paper presents the implementation of a twodimensional (2-D) finite-impulse-response (FIR) trapezoidal filter based beamforming array receiver. A 2.4 GHz 16-element receivemode IQ array is designed and used for physically measuring the beam patterns corresponding to 2-D FIR trapezoidal filters. The 16-element beamformer is implemented using the reconfigurable open architecture computing hardware version-2 (ROACH-2) field programmable gate array (FPGA) platform to perform analog to digital conversion and digital signal processing. The 2-D FIR trapezoidal filter is designed as a 16-spatial input 32- tap filter and is implemented targeting the ROACH-2’s Xilinx Virtex 6 (sx475t) FPGA chip as a filter-and-sum architecture. The receiver array is precisely rotated (keeping the transmitter fixed) to digitally measure the received energy by integrating the instantaneous power of the output of the 2-D FIR trapezoidal filter for each angle of reception. The main lobe of the measured beam pattern is well aligned with the simulated beam pattern, and the highest measured side-lobe level is −17.8 dB.