2,790 research outputs found

    Digital data transition tracking loop improves data reception

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    Transition tracking loop eliminates drifts, leakages, and instabilities inherent in analog filters. Major components are the phase detector, loop filter, voltage-controlled oscillator and timing logic

    Analog filtering in instrumentation using posicast

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    Analog filters are essential in industrial environments for noise reduction. The filter approximation that presents the best performance in noise reduction is Tchebyshev. This approximation introduces distortions in pulsed signals due to overshoot. The analysis and design of analog filters using a Posicast element are presented. Posicast is a feedforward compensator that reduces overshoot in system response. The authors present a direct method to design analog filters using Posicast, which is based on knowledge of the step response overshoot and system's damped time response period. Simulated results for two filters (Tchebyshev and Bessel) indicates that the new method reduces distortion in pulsed signals, without affecting its performance in frequency

    On Out-of-Band Emissions of Quantized Precoding in Massive MU-MIMO-OFDM

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    We analyze out-of-band (OOB) emissions in the massive multi-user (MU) multiple-input multiple-output (MIMO) downlink. We focus on systems in which the base station (BS) is equipped with low-resolution digital-to-analog converters (DACs) and orthogonal frequency-division multiplexing (OFDM) is used to communicate to the user equipments (UEs) over frequency-selective channels. We demonstrate that analog filtering in combination with simple frequency-domain digital predistortion (DPD) at the BS enables a significant reduction of OOB emissions, but degrades the signal-to-interference-noise-and-distortion ratio (SINDR) at the UEs and increases the peak-to-average power ratio (PAR) at the BS. We use Bussgang's theorem to characterize the tradeoffs between OOB emissions, SINDR, and PAR, and to study the impact of analog filters and DPD on the error-rate performance of the massive MU-MIMO-OFDM downlink. Our results show that by carefully tuning the parameters of the analog filters, one can achieve a significant reduction in OOB emissions with only a moderate degradation of error-rate performance and PAR.Comment: Presented at the 2017 Asilomar Conference on Signals, Systems, and Computers, 6 page

    Optimized Quality Factor of Fractional Order Analog Filters with Band-Pass and Band-Stop Characteristics

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    Fractional order (FO) filters have been investigated in this paper, with band-pass (BP) and band-stop (BS) characteristics, which can not be achieved with conventional integer order filters with orders lesser then two. The quality factors for symmetric and asymmetric magnitude response have been optimized using real coded Genetic Algorithm (GA) for a user specified center frequency. Parametric influence of the FO filters on the magnitude response is also illustrated with credible numerical simulations.Comment: 6 pages, 13 figures; 2012 Third International Conference on Computing, Communication and Networking Technologies (ICCCNT'12), July 2012, Coimbator

    Simulation and Realization of Some CMOS-Transconductor Vhf Filters

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    CMOS circuits for integrated analog filters at very high frequencies have been designed through PSPICE based on the Transconductance-C integrator. They have been implemented on the bread board and many filters i.e. LP, BP, Elliptic LP etc. are simulated and realized
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