Towards Optimised FPGA Realisation of Microprogrammed Control Unit Based FIR Filters

Finite impulse response (FIR) filter is one of the most common type of digital filter used in digital signal processing (DSP) applications. An FIR filter is usually realised in hardware using multipliers, adders and registers. Field programmable gate arrays (FPGAs) have been widely explored for the hardware realisation of FIR filters using different algorithms and techniques. One such technique that has recently gained considerable attention is the use of microprogrammed control unit (MPCU) in designing FIR filters. In this chapter, we further explore MPCU technique for optimised hardware realisation of digital FIR filter. To evaluate the performance, two different architectures of FIR filter are designed using Wallace tree multiplier. Both the architectures are coded in Verilog hardware description language (HDL). The performance is analysed by evaluating the resource utilisation and timing reports of Virtex-5 FPGA generated by the Synopsys Synplify Pro tool. Based on the implementation results, as compared to conventional design, Wallace tree multiplier using carry skip adder (CSKA) provides optimal digital FIR filter

Toward Realization of 2.4 GHz Balunless Narrowband Receiver Front-End for Short Range Wireless Applications

The demand for radio frequency (RF) transceivers operating at 2.4 GHz band has attracted considerable research interest due to the advancement in short range wireless technologies. The performance of RF transceivers depends heavily on the transmitter and receiver front-ends. The receiver front-end is comprised of a low-noise amplifier (LNA) and a downconversion mixer. There are very few designs that focus on connecting the single-ended output LNA to a double-balanced mixer without the use of on-chip transformer, also known as a balun. The objective of designing such a receiver front-end is to achieve high integration and low power consumption. To meet these requirements, we present the design of fully-integrated 2.4 GHz receiver front-end, consisting of a narrow-band LNA and a double balanced mixer without using a balun. Here, the single-ended RF output signal of the LNA is translated into differential signal using an NMOS-PMOS (n-channel metal-oxide-semiconductor, p-channel metal-oxide-semiconductor) transistor differential pair instead of the conventional NMOS-NMOS transistor configuration, for the RF amplification stage of the double-balanced mixer. The proposed receiver circuit fabricated using TSMC 0.18 µm CMOS technology operates at 2.4 GHz and produces an output signal at 300 MHz. The fabricated receiver achieves a gain of 16.3 dB and consumes only 6.74 mW operating at 1.5 V, while utilizing 2.08 mm2 of chip area. Measurement results demonstrate the effectiveness and suitability of the proposed receiver for short-range wireless applications, such as in wireless sensor network (WSN)

A Proposed Scalable Design and Simulation of Wireless Sensor Network-Based Long-Distance Water Pipeline Leakage Monitoring System

Anomalies such as leakage and bursts in water pipelines have severe consequences for the environment and the economy. To ensure the reliability of water pipelines, they must be monitored effectively. Wireless Sensor Networks (WSNs) have emerged as an effective technology for monitoring critical infrastructure such as water, oil and gas pipelines. In this paper, we present a scalable design and simulation of a water pipeline leakage monitoring system using Radio Frequency IDentification (RFID) and WSN technology. The proposed design targets long-distance aboveground water pipelines that have special considerations for maintenance, energy consumption and cost. The design is based on deploying a group of mobile wireless sensor nodes inside the pipeline and allowing them to work cooperatively according to a prescheduled order. Under this mechanism, only one node is active at a time, while the other nodes are sleeping. The node whose turn is next wakes up according to one of three wakeup techniques: location-based, time-based and interrupt-driven. In this paper, mathematical models are derived for each technique to estimate the corresponding energy consumption and memory size requirements. The proposed equations are analyzed and the results are validated using simulation

Selectively grown GaAs nanodisks on Si(100) by molecular beam epitaxy

The authors report the molecular beam epitaxial growth and the structural and optical characterizations of self-assembled/catalyst-free GaAs nanodisks on SiO2 masked Si(100) patterned substrates. Pure zincblende GaAs nanodisks with precise positioning and low defect density are demonstrated by selective area epitaxy. The influence of the growth temperature and deposition duration is investigated. Excellent morphological and structural properties are characterized by scanning electron microscopy and cross-sectional transmission electron microscopy. Defects in the epilayers are reduced by strain relaxation through facets formation and by a lateral overgrowth scheme atop the SiO2 mask which is corroborated by microRaman spectroscopy. In particular, the authors show how the material quality contributes to excellent optical properties observed by microphotoluminescence spectroscopy from 77 K to room temperature. (C) 2014 American Vacuum Society

Nanoscale Growth of GaAs on Patterned Si(111) Substrates by Molecular Beam Epitaxy

High-quality and defect-free GaAs were successfully grown via molecular beam epitaxy on silicon dioxide patterned Si(111) substrates by a two-step growth technique. Compared with the one-step approach, the two-step growth scheme has been found to be a better pathway to obtain a superior-quality GaAs on Si. Taking advantages of low energy for both Si(111) surface and GaAs/Si(111) interface, the two-step grown GaAs of total ∼175 nm atop patterned Si(111) substrates exhibits atomically smooth surface morphology, single crystallininty and a remarkably low defect density. A low-temperature GaAs nucleation layer of the two-step growth helps relieve the misfit stress by accommodating the misfit dislocations at the very adjacent GaAs/Si interface. The excellent properties of the two-step grown GaAs were investigated and verified by field-emission scanning electron microscopy, atomic force microscopy, X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. Finally we demonstrated a GaAs on Si solar cell, which could represent an important milestone for future applications in light-emitting diodes, lasers, and photodetectors on Si