Suhaidi Shafie

A CMOS Image Sensor Integrating Column-Parallel Cyclic ADCs with On-Chip Digital Error Correction Circuits

This paper presents a CMOS image sensor integrating a 14b column-parallel cyclic ADC with on-chip digital error correction circuits. Column-parallel ADC arrays are located both above and below the pixel array. The area of the on-chip error-correction logic including memories for all the error coefficients of the 640 ADC channels is 0.85mmx7.9mm.

Evaluation of Fuzzy Logic Subsets Effects on Maximum Power Point Tracking for Photovoltaic System

Photovoltaic system (PV) has nonlinear characteristics which are affected by changing the climate conditions and, in these characteristics, there is an operating point in which the maximum available power of PV is obtained. Fuzzy logic controller (FLC) is the artificial intelligent based maximum power point tracking (MPPT) method for obtaining the maximum power point (MPP). In this method, defining the logical rule and specific range of membership function has the significant effect on achieving the best and desirable results. This paper presents a detailed comparative survey of five general and main fuzzy logic subsets used for FLC technique in DC-DC boost converter. These rules and specific range of membership functions are implemented in the same system and the best fuzzy subset is obtained from the simulation results carried out in MATLAB. The proposed subset is able to track the maximum power point in minimum time with small oscillations and the highest system efficiency (95.7%). This investigation provides valuable results for all users who want to implement the reliable fuzzy logic subset for their works.

Non-Linearity in Wide Dynamic Range CMOS Image Sensors Utilizing a Partial Charge Transfer Technique

The partial charge transfer technique can expand the dynamic range of a CMOS image sensor by synthesizing two types of signal, namely the long and short accumulation time signals. However the short accumulation time signal obtained from partial transfer operation suffers of non-linearity with respect to the incident light. In this paper, an analysis of the non-linearity in partial charge transfer technique has been carried, and the relationship between dynamic range and the non-linearity is studied. The results show that the non-linearity is caused by two factors, namely the current diffusion, which has an exponential relation with the potential barrier, and the initial condition of photodiodes in which it shows that the error in the high illumination region increases as the ratio of the long to the short accumulation time raises. Moreover, the increment of the saturation level of photodiodes also increases the error in the high illumination region.

A Mobile Ferromagnetic Shape Detection Sensor Using a Hall Sensor Array and Magnetic Imaging

This paper presents a Mobile Hall Sensor Array system for the shape detection of ferromagnetic materials that are embedded in walls or floors. The operation of the Mobile Hall Sensor Array system is based on the principle of magnetic flux leakage to describe the shape of the ferromagnetic material. Two permanent magnets are used to generate the magnetic flux flow. The distribution of magnetic flux is perturbed as the ferromagnetic material is brought near the permanent magnets and the changes in magnetic flux distribution are detected by the 1-D array of the Hall sensor array setup. The process for magnetic imaging of the magnetic flux distribution is done by a signal processing unit before it displays the real time images using a netbook. A signal processing application software is developed for the 1-D Hall sensor array signal acquisition and processing to construct a 2-D array matrix. The processed 1-D Hall sensor array signals are later used to construct the magnetic image of ferromagnetic material based on the voltage signal and the magnetic flux distribution. The experimental results illustrate how the shape of specimens such as square, round and triangle shapes is determined through magnetic images based on the voltage signal and magnetic flux distribution of the specimen. In addition, the magnetic images of actual ferromagnetic objects are also illustrated to prove the functionality of Mobile Hall Sensor Array system for actual shape detection. The results prove that the Mobile Hall Sensor Array system is able to perform magnetic imaging in identifying various ferromagnetic materials.

Alternative Solar-Battery Charge Controller to Improve System Efficiency

When the heat losses sense is adopted for some solar system and power conversion components in residential building application, it is benefit to use those losses, that are consequently acts inversely on system efficiency, as a useful energy to modify the performance of that system instead of dissipated. In terms of efficiency of solar-battery charge controller, power dissipation is always associated with every power component and the losses would be either results from switching and conducting components or from the OFF state of the main switching component. This paper proposed a high efficiency solar-battery charge controller as an alternative to the main solar charge controller in most conventional residential solar system , the concept of the proposed controller circuit based on using the off state energy duration as well as that power losses coming from the main switching component and complexity of the conventional controller, and using this energy in a separate current path to energize an auxiliary battery or directly load used to cool or even to ventilate the system components causing in improving its performance. This will leads to electronic circuit with low losses as a compared with the conventional charge controller to be a part of the integrated and automated building solar system, the design has an algorithm based on some environment parameters like sun Irradiance and weather temperature, this algorithm seems to be inversely calculated because its start from the value of full charge battery voltage. A Simulink Matlab simulator is attempted in the simulation phase of this research as well as an experimental data has been collected to verify the circuit function and energy saving goal.

An RF Energy Harvester System Using UHF Micropower CMOS Rectifier Based on a Diode Connected CMOS Transistor

This paper presents a new type diode connected MOS transistor to improve CMOS conventional rectifiers performance in RF energy harvester systems for wireless sensor networks in which the circuits are designed in 0.18 μm TSMC CMOS technology. The proposed diode connected MOS transistor uses a new bulk connection which leads to reduction in the threshold voltage and leakage current; therefore, it contributes to increment of the rectifiers output voltage, output current, and efficiency when it is well important in the conventional CMOS rectifiers. The design technique for the rectifiers is explained and a matching network has been proposed to increase the sensitivity of the proposed rectifier. Five-stage rectifier with a matching network is proposed based on the optimization. The simulation results shows 18.2% improvement in the efficiency of the rectifier circuit and increase in sensitivity of RF energy harvester circuit. All circuits are designed in 0.18 μm TSMC CMOS technology.

A review on Solid State time of flight TOF range image sensors

This paper reviews three different types of Solid State time of flight TOF range image sensors. All of the sensors studied measure range by detecting the TOF of light using three different methods which are pulse modulation, sine wave modulation and time to digital converter TOF range image sensors. From the review it is found that the Power Dissipation of the SPAD i.e. single photon avalanche diode TOF image sensor is lowest which is 750uw. Range Resolution of the GOFO i.e. gate on field oxide structure TOF range image sensor is smaller which 2.35cm at 30fps and finally the Spatial Resolution of the GOFO TOF image sensor is largest which is 336 × 252 pixels.

A wide dynamic range CMOS image sensor with dual charge storage in a pixel and a multiple sampling technique

This paper presents a dynamic range expansion technique of CMOS image sensors with dual charge storage in a pixel and multiple exposures. Each pixel contains two photodiodes, PD1 and PD2 whose sensitivity can be set independently by the accumulation time. The difference of charge accumulation time in both photodiode can be manipulated to expand the dynamic range of the sensor. It allows flexible control of the dynamic range since the accumulation time in PD2 is adjustable. The multiple exposure technique used in the sensor reduces the motion blur in the synthesized wide dynamic range image when capturing fast-moving objects. It also reduces the signal-to-nose ratio dip at the switching point of the PD1 signal to the PD2 signals in the synthesized wide dynamic range image. A wide dynamic range camera with 320x240 pixels image sensor has been tested. It is found that the sampling of 4 times for the short accumulation time signals is sufficient for the reduction of motion blur in the synthesized wide dynamic range image, and the signal-to-noise ratio dip at the switching point of the PD1 signal to the PD2 signal is improved by 6 dB using 4 short-time exposures.

A review on high-resolution CMOS delay lines: towards sub-picosecond jitter performance

A review on CMOS delay lines with a focus on the most frequently used techniques for high-resolution delay step is presented. The primary types, specifications, delay circuits, and operating principles are presented. The delay circuits reported in this paper are used for delaying digital inputs and clock signals. The most common analog and digitally-controlled delay elements topologies are presented, focusing on the main delay-tuning strategies. IC variables, namely, process, supply voltage, temperature, and noise sources that affect delay resolution through timing jitter are discussed. The design specifications of these delay elements are also discussed and compared for the common delay line circuits. As a result, the main findings of this paper are highlighting and discussing the followings: the most efficient high-resolution delay line techniques, the trade-off challenge found between CMOS delay lines designed using either analog or digitally-controlled delay elements, the trade-off challenge between delay resolution and delay range and the proposed solutions for this challenge, and how CMOS technology scaling can affect the performance of CMOS delay lines. Moreover, the current trends and efforts used in order to generate output delayed signal with low jitter in the sub-picosecond range are presented.

GPS based portable dual-axis solar tracking system using astronomical equation

The overall objective of this study is to design and develop a portable dual-axis solar tracking system that focuses on portable and mobility purpose. This paper discusses the design, electronic control system and the algorithm based on the astronomical equation. The tracking system utilizes the GPS module and a digital compass sensor for determining the location and the heading feedback of the system respectively. Moreover, the microcontroller based tracking system is embedded with a PID controller for which will increase the PV positioning accuracy based from the feedback signal of the absolute encoder. Furthermore, this paper also analyses and compares the performance between the fixed-tilted PV panel and the developed portable solar tracking system.