Nasri Sulaiman

FPGA-Based Fuzzy Logic: Design and Applications – a Review

— A large numbers of fuzzy control applications with the physical systems require a real-time operation to interface high speed constraints; higher density programmable logic devices such as field programmable gate array (FPGA) can be used to integrate large amounts of logic in a single IC. This paper reviews the state of the art of FPGA with the focus on FPGA-based fuzzy logic controller. The paper starts with an overview of FPGA in order to get an idea about FPGA architecture, and followed by an explanation on the hardware implementation with both type analogue and digital implementation, a comparison between fuzzy and conventional controller also provided in this paper. A survey on fuzzy logic controller structure is highlighted in this article with the focus on FPGA-based design of fuzzy logic controller with different applications. Finally, we provided the simulation and experimental results form the literature and concluded the main differences between software-based systems with respect to FPGA-based systems, and the main features for FPGA technology and its real-time applications.

Efficiency improvement in microwave power amplifiers by using Complex Gain Predistortion technique

Power Amplifiers (PAs) are important parts of the transmitters. They amplify the signals that are going to be transmitted. With increasing the input power of the PA, it creates the nonlinearity at the output. The nonlinearity causes out of band distortion and in band distortion. To overcome these effects the power amplifier should be backed off but it will reduce the efficiency of the PA. To increase the efficiency, the Complex Gain Memory Predistortion (CGP) is added to the system. Experimental results with the Mini Circuit power amplifier show an improvement of 7% in Power Added Efficiency (PAE) when the CGP method is applied.

A low complexity selected mapping scheme for peak to average power ratio reduction with digital predistortion in OFDM systems

One of the effective methods used for reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems is selected mapping (SLM). In this paper, a new SLM scheme called DSI-SLM, which is a combination of dummy sequence insertion (DSI) and conventional selected mapping (C-SLM) is proposed. Previous techniques have had some drawbacks. In DSI, increasing the number of dummy sequences to have better PAPR degrades transmission efficiency, and in C-SLM, the complexity rises dramatically when the number of sub-blocks increases. The proposed DSI-SLM scheme significantly reduces the complexity because of the reduction in the number of sub-blocks compared with the C-SLM technique while its PAPR performance is even better. To enhance the efficiency of the OFDM system and suppress the out-of-band distortion from the power amplifier nonlinearity, a digital predistortion technique is applied to the DSI-SLM scheme. Simulations are carried out with the actual power amplifier model and the OFDM signal based on the worldwide interoperability for microwave access standard and quadrature phase-shift keying modulation. The simulation results show improvement in PAPR reduction and complexity, whereas the BER performance is slightly worse.

A new DSI-SLM method for PAPR reduction in OFDM systems

High PAPR is the main drawback of OFDM systems. DSI method and SLM method are two of the most promising techniques to reduce PAPR.

Peak-to-average power ratio reduction based on Cross-Correlation in OFDM systems

Two of the most important techniques of Peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems are Partial Transmit Sequence PAPR (PTS-PAPR) and Cross-Correlation-PTS. This paper investigates a complete analysis on these two techniques providing simulation and discussion of their performance on PAPR reduction and bit error rate (BER). Moreover the comparison of these methods by using Saleh model amplifier in an OFDM system is provided. The results show that PTS-PAPR outperforms the Cross-Correlation-PTS in terms of PAPR performance while Cross-Correlation-PTS method is more efficient in BER reduction.

Power Efficiency in Broadband Wireless Communications

Power Efficiency in Broadband Wireless Communications focuses on the improvement of power efficiency in wireless communication systems, especially of mobile devices. Reviewing cutting-edge techniques for conserving power and boosting power efficiency, the book examines various technologies and their impact on consumer devices. It considers each technology, first by introducing the main physical layer components in recent wireless communication systems along with their shortcomings, and then proposing solutions for overcoming these shortcomings.The book covers orthogonal frequency division multiplexing (OFDM) signal generation and formulation and examines the advantages and disadvantages of OFDM systems compared to alternative multiplexing. It introduces one of the main drawbacks of OFDM systems, peak-to-average power ratio (PAPR), and discusses several PAPR techniques. It also explains how to overcome the main drawbacks of real-world OFDM system applications. Considers power amplifier linearization for increasing power efficiency and reducing system costs and power dissipation Describes the implementation scenario of the most promising linearization technique, digital predistortion Presents some experimental demonstrations of digital predistortion when the device under test is in the loop Because the most costly device in a communication system that has a direct impact on power efficiency and power consumption is the power amplifier, the book details the behavior and characteristics of different classes of power amplifiers. Describing the evolution of the mobile cellular communication system, it details a cost-effective technique to help you increase power efficiency, reduce system costs, and prolong battery life in next generation mobile devices.

Power amplifier linearisation scheme to mitigate superfluous radiations and suppress adjacent channel interference

Power amplifiers are one of the costly devices in wireless communication systems and exhibit non-linearity. The problem of non-linearity in the power amplifier categorises in two disturbance impacts, output distortion and in-band distortion which lead to adjacent channel interference and constellation deviation, respectively. In order to gain maximum efficiency of the power amplifier and reduce interference, the authors propose a new digital pre-distortion scheme called complex gain convergence (CGC). The proposed scheme is compared with indirect learning architecture and validated against an laterally diffused metal oxide semiconductor (LDMOS) power amplifier. The outcome of applying CGC scheme shows enhancement in adjacent channel leakage ratio and error vector magnitude performance while the complexity is even lower. An experimental demonstration with the actual power amplifier is also presented.

Transistor sizing methodology for low noise charge sensitive amplifier with input transistor working in moderate inversion

In this paper noise contribution of current source transistors and sizing methodology in charge sensitive amplifier for application in the front-end readout electronics is presented. In modern deep-submicron technologies, MOS transistor operating region tends to shift from strong inversion to moderate inversion, this makes traditional square-law MOS device modeling not applicable anymore. Thus a simplified EKV model, which is quite successful in all CMOS operating regions, has been adopted to develop a new analytical methodology to optimize geometry of current source transistors so that the noise contribution from these transistors is only a fraction of input transistor noise. A charge sensitive amplifier based on dual PMOS cascode structure is designed by adopting this current source transistor sizing methodology, and has been simulated using 130nm CMOS technology. The proposed methodology and noise contribution from current source transistors have been found in good agreement with simulation results using deep-submicron CMOS technology.

Review on policies, research & development in microelectronics industry in Malaysia

In this paper, the scenario of the microelectronics industry in Malaysia is described. The governments policies, infrastructure, and government-industry partnership program, as well incentives provided by the government to nourish the industry were also discussed. A special wafer fabrication task force has been formed to ensure the success of this strategic project.

A recursive optimum frequency domain matrix to reduce crest factor in OFDM systems

One of the main imperfections in orthogonal frequency division multiplexing (OFDM) technique is a peak-to-average power ratio (PAPR) or crest factor (CF). High crest factor signal forces a power amplifier in communication systems to back-off which leads to power efficiency degradation. Several techniques have been proposed in literature to mitigate the high peaks in OFDM signal; however most of them suffer from complexity and PAPR performance. In this paper a novel crest factor scheme based on recursive optimum frequency domain matrix is proposed which requires only two IFFT which results in significant reduction in the computational complexity. Simulation results show both the complexity and crest factor are reduced significantly compared to the conventional methods.