A bandwidth adjustable integrated optical receiver having an on-chip silicon avalanche photodetector is realized with standard 0.25-µm silicon-germanium bipolar complementary metal-oxide-semiconductor technology for optical interconnect applications. With the controllable capacitive degeneration technique, the optical receiver bandwidth can be adjusted for the best bit error rate performance.

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A novel planar CPW-fed passive tag antenna that may be mounted on a metallic object is presented to meet UHF radio frequency identification (RFID) applications. It comes with a slot radiator and an inverted-C shaped coupling structure, which is fabricated on a 0.4mm-thick FR4 substrate to be attached on a 3mm-thick polypropylene (PP) substrate. No additional matching circuit is required with our design, so a compact tag size of 93(L)×20(W)×3.4(H)mm³ can be obtained. With a proper operating bandwidth from 915 to 929MHz, the proposed tag can achieve maximum reading ranges of 7.4m and 4.7m when used with and without a metallic plate for 4W EIRP.

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In this work, a low noise regulated charge pump circuit is presented. The proposed charge pump uses a digital frequency shaped clock scheme to spread tonal energy of the oscillator to overall frequency ranges, and reduces the output noise of the charge pump, and improves the power efficiency. To achieve constant output voltage during an over loading condition, the proposed charge pump utilizes feedback. The proposed charge pump generates 4.1V ∼ 4.4V output voltage and provides 30mA current driving capability with 30mV ripple at 2.5V ∼ 3.5V supply line. At 800MHz ∼ 2.2GHz ranges, the output noise power of the proposed charge pump is at least 11.4dBm less than that of a charge pump with normal clock.

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A novel compact band-notch ultra-wideband (UWB) printed monopole antenna is proposed, where the band notch characteristic is realized by inserting a pair of hook-shaped slit in the both side of radiating patch. Also, by inserting a π-shaped stub in the ground plane, additional resonance is excited and hence the bandwidth is increased up to 123%. This novel monopole antenna has ultrawide impedance bandwidth, compact size, low fabrication cost, and omni-directional H-plane radiation patterns which are suitable for various broadband applications.

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To achieve more cost-effective assignment of real-time tasks to actors in wireless sensor actor networks we propose a distributed auction-based protocol that uses tasks' deadlines, actors' energies, actors' loads and actors' distances from event area as a cumulative cost metric. The protocol chooses actors closest to event area with lowest loads and highest remaining energies to minimize the response time of tasks, balance loads on actors and maximize total remaining energy of actors. Simulations show higher deadline meet-ratio and remaining energies of actors, and more balanced loads on actors, compared to SAP and SAAP task-assignment protocols.

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In ultra-wideband (UWB) channels, the signal energy in the acquisition receiver spreads over correlator outputs due to rich multipaths, making the output of each correlator have only a small portion of the total energy. To enhance the acquisition performance for UWB signals by exploiting the signals spread over a number of correlator outputs, this paper proposes a two-stage acquisition scheme. In the proposed scheme, decision variables are formed by combining a multiple of correlator outputs, allowing it possible to make use of the signal energy spread over the outputs jointly. Simulation results show that the proposed scheme can provide a gain of about 0.6dB over the conventional schemes in various UWB channel environments.

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In this letter, we propose a new technique that combines space time coding (STC) with pre-FFT multibeamforming for a multi-input multi-output (MIMO)-orthogonal frequency division multiplexing (OFDM) system. The proposed approach can effectively cancel a cochannel interference (CCI) while preserving the STC diversity and can mitigate the impairment of delay spread. The performance improvement of the proposed approach is investigated through computer simulation in a multipath channel with CCI.

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A fast settling multipath CMOS OTA for high speed switched capacitor applications is presented here. With the basic topology similar to folded-cascode, bandwidth and DC gain of the OTA are enhanced by adding extra paths for signal from input to output. Designed circuit is simulated with HSPICE using level 49 parameters (BSIM 3v3) in 0.35um standard CMOS technology. The DC gain achieved is 56.7db and the Unity Gain Bandwidth (UGB) obtained is 1.15GHz.

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A novel two-transistor (2T) programmable element instead of the traditional 6T SRAM element in field programmable gate array (FPGA) is proposed. The key FPGA components, such as lookup table (LUT) and routing structure are modified when applying the 2T element. A restore algorithm is applied to prevent the configuration information lost due to charge leakage. A CAD evaluation demonstrates that the density and the performance of FPGA can be improved by 25% and 19% respectively.

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Recently, client-side attacks through the Microsoft Internet Explorer have increased. In this paper, we present a method to detect and block malware programs resulting from successful malicious iframe attacks. This method can detect malware program execution through distinguishing API sequences of normal execution and abnormal API sequences resulting from an exploit using Win32 API hooks. We implemented MiGuard (Guard against malicious iframes) and performed experiments. The evaluation results indicate that our approach can effectively detect and block malicious iframes. We also believe that our research can help prevent threats of malicious iframes.

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The wireless mesh networks have been a very promising solution for providing last few miles wireless connectivity in the metropolitan area networks. A new medium access control scheme is proposed to improve throughput in wireless mesh networks. The proposed scheme is to adjust the minimum size of contention window of mesh clients according to the information of transmission queue at relay nodes. The relay node carries the load information on an ACK frame by using the reserved subtype fields. The proposed scheme gives a priority to the relay node for transmitting packets when the relay node becomes a bottleneck. The simulation results show much better performance from the proposed scheme in comparison with that from original CSMA/CA scheme.

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This paper deals with the problem of spectrum sharing among primary and secondary users in a cognitive radio. To use the spectrum efficiently and flexibly, the cognitive radio spectrum allocation problem was formulated as a graph coloring problem (GCP). However, GCP is known to be a nondeterministic polynomial-time (NP)-hard and cannot be solved for the practical system. Inspired by the efficiency of the cross-entropy (CE) method for finding near-optimal solutions in huge search spaces, this paper proposes the application of the CE method to allocate cognitive radio spectrum to achieve near-optimal spectrum utilization. Simulation results show that the average reward values obtained using the proposed CE method are better than those obtained using the conventional method.

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A novel full adder cell is designed so that it can overcome the challenges of circuit design in deep submicron (DSM) technology. The proposed adder cell utilizes multiplexing control input techniques (MCIT) for the sum operation and uses a new arrangement of pass transistors for carry operation. The adder is then used in an 8×8bit Braun-array multiplier to show its performance. The layout of multiplier is simulated in 32nm CMOS technology by Microwind31 (MW31) VLSI CAD TOOL. Simulated results show that our circuit operates properly in nanoscale and has a very small area.

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The design of concentric ring arrays for isoflux radiation is reported in this paper. This design considers the reduction of the side lobe level and the isoflux radiation requirements for Geostationary Earth Orbit (GEO) satellites. The optimization problem considers the spacing between rings and the levels of amplitude excitations. The well-known method of Particle Swarm Optimization (PSO) is utilized for the optimization. The obtained results could lead the satellite hardware to be reduced significantly even more that results presented previously in the literature.

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A novel electro-optic (EO) microwave-lightwave converter using a patch antenna embedded with a narrow gap is proposed and experimentally demonstrated. By embedding a narrow gap at the center of the patch antenna and an optical waveguide located under the gap, a wireless microwave signal can be received and converted to an optical signal directly through EO modulation of a lightwave propagating in the optical waveguide. In the experiment, optical sidebands were observed clearly with the irradiation of an 18GHz wireless signal to the fabricated prototype device. This device operates with no external power supply and no additional modulation electrode. Therefore, it can be operated with low microwave distortion.

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In recent years, cooperative communication has been widely investigated to improve performance of wireless communication networks based on Orthogonal frequency division multiple access (OFDMA). Cooperative communication is applied to single-antenna system at the destination. However, in the OFDMA uplink network, the base station (BS) is simply equipped with multiple antennas. Therefore, cooperative diversity and multiplexing schemes can be easily applied in the BS with multiple antennas. In this letter, to guarantee reliability with high throughput simultaneously, we propose a cooperative hybrid cyclic delay diversity (CDD) scheme which can use an arbitrary number of relays without rate loss and a modification of the BS although the number of relays is changed.

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We propose that electrochemical cells based on bacterioRhodopsin (bR), a photosensitive protein, generate electric charges under illuminated light and that a suitable signal detection apparatus for this cell type is a charge amplifier. By using charge amplifiers, we observed bR-photocell electric charges that were proportional to the intensity of incident light, which ranged from 0 to 8mW/cm². Then, the 4 × 4 micro-patterned bR photosensor array was connected to charge amplifiers to form an image sensor system. Static and moving images were detected with the constructed image sensor system.

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This paper proposes an ultra compact LC-VCO. Due to the speed-up of CMOS digital circuits, jitter of ring oscillators is becoming a critical problem. Even though an LC-VCO has a better phase noise, a layout size of on-chip inductor is a problem as a clock generator. Thus, the proposed LC-VCO consists of a very compact stacked-spiral inductor and active components placed are beneath the inductor. The VCO is implemented by a 65-nm CMOS process, and the chip area is only 594µm². This VCO achieves a phase noise of -93dBc/Hz@1MHz, power consumption of 0.36mW, and FOMA of 210dBc/Hz.

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This paper presents an ultra-wide-range all-digital delay-locked loop (DLL). The proposed DLL uses a novel delay circuit which uses the transistor's leakage current in advanced CMOS process to generate a very large propagation delay. Thus, the proposed DLL can operate at very low frequency with small chip area and low power consumption. The proposed DLL can operate from 600kHz to 1.2GHz in the typical case. The power consumption of the DLL is 2.6mW at 1.2GHz and 0.366mW at 600kHz with 1.0V power supply. The measured r.m.s jitter and peak-to-peak jitter at 1.2GHz are 3.38ps and 39.29ps, respectively.

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For pilot-aided channel estimation in OFDM systems with a large number of subcarriers, an efficient discrete Fourier transform(DFT)-based interpolator is proposed. To suppress the leakage in a conventional DFT-based interpolator, the proposed method simply reuses the channel frequency response (CFR) estimates at leftmost and rightmost pilot subcarriers.

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