2009/4

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    An Ultra-Low-Voltage and Ultra-Low-Power 2.4 GHz LNA Design
    (Společnost pro radioelektronické inženýrství, 2009-12) Liu, Baimei; Wang, Chunhua; Ma, Minglin; Guo, Shengqiang
    In this paper, ultra-low-voltage and ultra-low-power circuit techniques are presented for CMOS RF front-ends. By employing a modified current-reused architecture, the low-noise amplifier (LNA) can operate at a very low supply voltage with microwatt power consumption while maintaining reasonable circuit performance at 2.4 GHz. Using a TSMC 0.18 um CMOS process, from the simulation results, the fully integrated LNA exhibits a gain of 14.4 dB and a noise figure of 1.6 dB at 2.4 GHz, operated at a supply voltage of 0.9 V, the input matching (S11) is –18.1 dB while consumes only 960 μW. example.
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    Fast Keyword Spotting in Telephone Speech
    (Společnost pro radioelektronické inženýrství, 2009-12) Nouza, Jan; Silovsky, Jan
    In the paper, we present a system designed for detecting keywords in telephone speech. We focus not only on achieving high accuracy but also on very short processing time. The keyword spotting system can run in three modes: a) an off-line mode requiring less than 0.1xRT, b) an on-line mode with minimum (2 s) latency, and c) a repeated spotting mode, in which pre-computed values allow for additional acceleration. Its performance is evaluated on recordings of Czech spontaneous telephone speech using rather large and complex keyword lists.
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    Modeling of Scientific Images Using GMM
    (Společnost pro radioelektronické inženýrství, 2009-12) Svihlik, Jan
    This paper deals with modeling of scientific and multimedia images in the wavelet domain. Images transformed into wavelet domain have a special shape of probability density function (PDF). Thus wavelet coefficients PDFs are usually modeled using generalized Laplacian PDF model (GLM), which is characterized by two parameters. The wavelet coefficients modeling can be more efficient, while the Gaussian mixture model (GMM) is utilized. GMM model is given by addition of at least two Gaussian PDFs with different standard deviations. The equation system derived by moment method for GMM model parameters estimation will be presented. The equation system was derived for an addition of two GMM models. So it is suitable for advanced denoising systems, where an addition of two GMM random variables is considered (e.g. dark current). This paper presents a continuing of previous work [11], deals with dark current elimination (novel approach) and shows a better way of to modeling light image and dark current.
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    Explicit-Current-Output Quadrature Oscillator Using Second-Generation Current Conveyor Transconductance Amplifier
    (Společnost pro radioelektronické inženýrství, 2009-12) Lahiri, Abhirup
    This paper presents a novel quadrature sinusoidal oscillator using second-generation current conveyor transconductance amplifier as an active building block. The proposed circuit employs only a single second-generation current conveyor transconductance amplifier, four passive components. The proposed circuit offers the advantages of independent control of the condition of oscillation and frequency of oscillation, availability of two explicit quadrature current outputs and two quadrature voltages, use of allgrounded passive elements and low active and passive sensitivities. The workability of the proposed circuit is confirmed by SPICE simulations.
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    Embedded Platform for Automatic Testing and Optimizing of FPGA Based Cryptographic True Random Number Generators
    (Společnost pro radioelektronické inženýrství, 2009-12) Varchola, Michal; Drutarovsky, Milos
    This paper deals with an evaluation platform for cryptographic True Random Number Generators (TRNGs) based on the hardware implementation of statistical tests for FPGAs. It was developed in order to provide an automatic tool that helps to speed up the TRNG design process and can provide new insights on the TRNG behavior as it will be shown on a particular example in the paper. It enables to test sufficient statistical properties of various TRNG designs under various working conditions on the fly. Moreover, the tests are suitable to be embedded into cryptographic hardware products in order to recognize TRNG output of weak quality and thus increase its robustness and reliability. Tests are fully compatible with the FIPS 140 standard and are implemented by the VHDL language as an IP-Core for vendor independent FPGAs. A recent Flash based Actel Fusion FPGA was chosen for preliminary experiments. The Actel version of the tests possesses an interface to the Actel’s CoreMP7 softcore processor that is fully compatible with the industry standard ARM7TDMI. Moreover, identical tests suite was implemented to the Xilinx Virtex 2 and 5 in order to compare the performance of the proposed solution with the performance of already published one based on the same FPGAs. It was achieved 25% and 65% greater clock frequency respectively while consuming almost equal resources of the Xilinx FPGAs. On the top of it, the proposed FIPS 140 architecture is capable of processing one random bit per one clock cycle which results in 311.5 Mbps throughput for Virtex 5 FPGA.