Microelectronics Engineering

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http://etd.aau.edu.et/handle/12345678/194

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Leakage Aware Hardware Architecture and Dynamic Power Scheduling
(Addis Ababa University, 2011-07) Dilbie, Daniel; Alemu, Getachew(PhD)
In the last couple of decades, battery powered mobile devices such as smart phones have become one of the most prolific electronic devices in history. With this has come an exploding demand for performance and features that cover almost every aspect of our digital multimedia interconnected lives including 3-D gaming, still and video cameras, WAN, Bluetooth, highspeed data connections, and so on. As ever increasing features continue to be integrated into these products, there is an ongoing need to develop innovative ways to reduce power consumption and extend battery life. A core requirement of effective and efficient management of energy is a good understanding of where and how the energy is used: how much of the system’s energy is consumed by which parts of the system and under what circumstances. In this work, a Smartphone is developed, hereafter referred to as the XLP, from the ground up with modular architecture where each module is supplied through an active switch matrix which is memory mapped and updated periodically by the main applications processor in the system. The basic notion of this architecture is achieving zero-leakage power for modules which are not being used. This significantly reduces the idle power consumption which accounts for more than 60% of the average power consumed in smart phones. In addition to this novel approach on the hardware architecture, a stochastic dynamic power scheduling and on-demand power and clock gating policies are developed. A number of possible policies are presented and, under given conditions, one of them is proved to be optimal using the energy response time product (ERP) metrics. The XLP is compared with three commercial smart phones, Openmoko Freerunner, HTC Dream and Google’s Nexus One on similar tests and usage scenarios. The XLP and all these three devices use the ARM microprocessor and run the Linux kernel. The comparison is on performance and power consumption. The XLP is proved to have the lowest power consumption on competitive performance levels.
Design of an Improved ADPLL For Dual Band GSM
(Addis Ababa University, 2013-02) Gosa, Demissie; Daniel, Dilbie (Mr.)
All Digital Phase Locked Loop are widely used frequency synthesizers in different radio communication systems. To use analog phase locked loop in different processes is difficult due to its process sensitivity. In conventional all digital phase locked loop all blocks are defined to be digital at both input and output level. In normal all digital phase locked loop the analog parts degrade the performance of the whole system related to frequency of operation. The new ADPLL architecture, which is the digital counter part of conventional CPPLL, is designed by discritizing conventional charge pump phase locked loop. It is designed using digital blocks in the new architecture, isolation rings and bulky loop filter components are replaced, and hence the system can become area efficient, consumes less power and low jitter. The digital block used in the design in place of analog charge pump help the application to be free of analog charge pump pitfalls like charge pump mismatch, leakage, thermal noise, aging and drift. Moreover, using the new architecture the system is made stable and hence more portable and robust operation. Higher rate clocks and huge processing time problems at the controller end is reduced using digital block used in the architecture. In a nutshell the design of integrated circuit is targeted for 900 MHz and 1800 MHz center frequencies with tuning range of 200 MHz and is done in UMC 130 nm technology. It consumes an average current of 13mA and applicable for 1.2V supply voltage. The chip area is less than 0.12mm2 and the average settling time is 3.55 usec.
Design and Simulation of a Wireless Based Transcutaneous Electrical Nerve Stimulator for Pain Control
(Addis Ababa University, 2016-10) Paulos, Ashenafi; Alemu, Getachew (PhD)
Pain is general term for unpleasant sensory and emotional experience associated with actual or potential tissue damage. For this reason, pain control and management is an important welfare concern even in routine management procedures of patients. The most widely used controls for pain at the present time are narcotic treatments. Recently, electrical nerve stimulation has emerged as a new mechanism for pain control that replace the narcotics which is a mechanism of injecting electrical impulse to the surface of the human body that suppressed the pain, but almost all developed systems are wired based and are not user friendly. Whereas, the narcotics most commonly prescribed have not only had a number of worrisome side effects, but also the cost is high and not affordable by most of the patients specifically in developing countries. In this thesis a wireless programmable microcontroller based transcutaneous electrical nerve stimulator has been designed and simulated, and the designed system gives a chance to the user to choose from the different types of stimulation parameters, like amplitude, frequency, pulse width, and duration, for how long the stimulation should be maintained. To achieve the specific advantages, the designed system uses eight levels of frequency, six levels of pulse-width, and four selectable stages which has been tested on ISIS PROTEUS DESIGN SUIT software, and for the programming parts of the design, mikro C PRO software for PIC language which is a popular high-level C programming language and Arduino Programming Language Software which is a simplified version of C/C++ has been accustomed. In summary, the proposed system gives different conditions of operations for the subject body to control the pain and overcome the drawbacks of the narcotics. It is flexible and user-friendly compared to the already built transcutaneous electrical nerve stimulation (TENS) systems that are available on related literatures and market. Keywords - Pain, Pain control and management, Wireless microcontroller based stimulation, Electrical nerve stimulation, and Transcutaneous electrical nerve stimulation (TENS) system.
Integration of Electronics and Photonics on Monolithic Silicon to Improve the Performance of Conventional Electronic Devices
(AAU, 2016-12) Hagos, Gebreyesus; Getachew, Alemu (PhD)
Conventional electronics have shown dramatic improvement in dimensions and performances over the last four decades and plays a great role in computing, storing, transmitting and retrieving data in all electronic devices. However, chip-to-chip and on-chip interconnect which have affected by a parasitic load became the real performance bottleneck due to its extremely reduced cross section dimension along with moore‘s law. Now, there are metal (copper) interconnections and dielectric materials in IC fabrications that faces great challenges for the future in the electronics, imposing problems of interconnect that the performance and functionality of conventional electronic devices are leading their physical limit in speed, bandwidth, power consumption (heating) and electromagnetic interference. In contrary, photonic devices have advantages like large bandwidth, lower power consumption (low heating) and immune to electromagnetic interference. So an integrated electro-photonic interconnect have seen an alternate solution for the future technology nodes due to their special physical characteristics. Therefore in order to overcome these electronic limitations ha ve been faced, an integrated electronics and photonics on monolithic silicon substrate has been proposed as a potential solution by merging the advantage of both technologies, electronics for data processing and storing while photonics for both on-chip and off-chip interconnection to obtain a future supper computing device. To study the integration of electronics and photonics on monolithic silicon substrate to improving the performance of conventional electronic devices, two experimental set up were prepared on laboratory at device level. The first experimental set up was integrated electronic and photonic interconnect. Its components were connected with waveguide or glass rod and represented by electrophotonic interconnect. The second experimental set up was conventional electronic circuit. Its components were connected by copper wire (Cu). Both experiments had similar three different lengths (30, 10, and 5) cm of Cu wire and waveguide at  of 1mm and 1cm respectively for both voltage and current output measurements from the system. And both experiments had again similar three different  (13, 9, and 6) mm of Cu wires and (1, 0.5, and 0.2) mm of waveguides at equal length of 25cm for delay and powe r measurements in the system at different clock frequencies (50, 75 and diameters 100) kHz. Comparisons were made and based on the result found electrophotonic interconnect performed better than that of the Cu interconnect in terms of delay and power. Therefore, delay and power dissipation on Cu interconnect was higher than electrophotonic interconnect by 62.8% and 60% respectively.
FPGA Based Optimum-Settling Automatic Gain Control Circuit Design for Multistage Amplification
(Addis Ababa University, 2018-03) Abreha, Teklu; Mohammed, Abdo (Prof.)
Many electronic applications require their input signal to be of constant amplitude. Especially, in communication systems, the transmitted signal may be faded and the amplitude of the received signal may be below the desired level due to multi-path fading and different positions. This thesis work solves problems of inconsistent amplitude signal arrival at receiving sides of electronic systems. Automatic Gain Control (AGC) circuits are mainly used in such applications to adjust the gain of a Variable Gain Amplifier (VGA) and to provide relatively constant amplitude signal to the receivers. This work makes use of multi-stage amplification circuits to increase the dynamic range of the AGC. Three amplification stages are designed which increased the gain from 21 dB in single stage to 63 dB in three stages. Due to their flexibility better than ASICs as well as high performance speed and better power efficiency than microcontrollers, FPGAs are preferred in modern high speed technologies. Consequently, this thesis work used FPGAs to generate control voltages to adjust the gain of VGAs in the multistage amplification circuit. The designed AGC employs both feedback and feedforward loops to optimize the settling time. Feedback loop is used in input stage and feedforward loop is used in intermediate and output stages. When the amplitude level of the input signal diverges from the desired level, the FPGA generates a control voltage that adjusts the gain of the VGA and the result is an output signal with consistent amplitude level. A reference input of 25 mVpeak is considered and the AGC circuit is tested with input signals of amplitude below and above the chosen reference value. For all tested inputs a constant amplitude signal of 87 mVpeak is achieved.
Configurable Analog Circuit Synthesis and Implementation Kit: PCB Based Approach
(2018-05-15) Abisa, Girma; Getachew, Alemu (PhD)
The implementation of newly designed analog circuits in most cases is a merger of known analog circuit blocks. The testing of these analog circuits have challenges like schematic to prototype part discrepancy, being cumbersome, fragility and component value variation. Field Programmable Analog Array (FPAA), could be considered analog counterparts FPGA, have been used for the design and development analog circuits. FPAAs combine CAD tool with rapid prototyping of analog circuits. FPAAs are monolithic programmable and generic analog circuit building tools. In this paper a configurable PCB based analog circuit builder kit is to be designed and built as a possible rugged alternative to FPAAs. The need for this alternative is put forward to utilize the advantages of FPPAs in a more rugged and accessible analog circuit building. This kit contains real analog circuit components with configurable interconnecting switches on a single board. The building and validation testing of such a kit is performed in this research. It can handle more power and larger components. It contains on board power supplies and component banks. This kit could be instrumental in the education/training of analog circuit design both in academia and industry.
Study and Evaluation of Multilayer PCB Manufacturing Inaccuracies on Malfunctioning of Circui
(Addis Ababa University, 2018-06) Hgigat, Aregawi; Mohammed, Abdo (Prof.)
The PCB is a mechanical base used for interconnection of electronic components. In PCB manufacturing industry, the quality and reliability of circuits is highly dependent upon the accuracy of the manufacturing processes. Because of the different factors affecting the processes to function imperfectly, manufacturing processes inaccuracies like photolithography inaccuracy, etching inaccuracy, drilling inaccuracies and inaccuracies in other processes may be encountered. These inaccuracies cause severe problems that may result in degradation of circuit performance and malfunctioning of circuits. In this research the levels of effects of the manufacturing inaccuracies on the malfunctioning of PCB circuits is investigated and analyzed. The effects of each process inaccuracies on circuits as well as how the processes are related with the affecting parameters are addressed in this thesis. A four-layer multilayer board is considered and the software selected to study the effects of manufacturing inaccuracies is OrCAD PCB designer. The major PCB manufacturing processes considered are Photolithography, Etching, and Drilling. Schematic development, PSpice simulation and layout design are made for selected circuits to study the effects of inaccuracies. According to the results obtained, drum speed, resolution and ratio of track to track spacing are the affecting parameters in Photo plotting while depth of focus, dose and mask bias variations are the factors affecting photolithography. In addition, inaccurate etching results in either larger or smaller width of traces, leaves unwanted conductive materials, creates unnecessary holes or open circuits and short circuits. In the case of drilling, when there is wrongly or inappropriately drilled, the top and bottom layers may not be connected and creates open circuit. In the over etching case simulation, 64 % of the output voltage reduction occurred for a 69% increase in resistance. This simply considering only one simple scenario the effect will be even worsened when similar individual effects are added to it. For capacitive effects, the output becomes unstable and oscillating.
Investigation of Soft Neural Network Algorithm Implement to Analog Electronics Devices
(Addis Ababa University, 2018-12-31) Eyob, Gedlie; Getachew, Alemu (PhD)
The implementation of neural systems is presented in this paper. The thesis focuses on implementations where the algorithms and their physical support are tightly coupled. This thesis describes a neural network intelligent, application, soft-algorithm to implement to hardware electronics device. With the emerging of Integrated Circuit, any design with large number of electronic components can be squeezed into a tiny chip area with minimum power requirements, which leads to integration of innumerable applications so as to design any electronic consumer product initiated in the era of digital convergence. One has many choices for selecting either of these reconfigurable techniques based on Speed, Gate Density, Development, Prototyping, simulation time and cost. This thesis describes the implementation in hardware of an Artificial Neural Network with an Electronic circuit made up of Op-amps. The implementation of a Neural Network in hardware can be desired to benefit from its distributed processing capacity or to avoid using a personal computer attached to each implementation. The hardware implementation is based in a Feed Forward Neural Network, with a hyperbolic tangent as activation function, with floating point notation of single precision. The device used was an electronic circuit made with Op-amps The Proteus Software version 8.0 was used to validate the implementation results of the hardware circuit. The results show that the implementation does not introduce a noticeable loss of precision but is slower than the software implementation running in a PC.
Analysis of The Functional Variation of Cascaded Amplifier When Replaced with Their Spintronics Equivalents
(Addis Ababa University, 2019-07) Ermias, Tewabe; Getachew, Alemu (PhD)
Spintronics is a new technology that employs the spin degrees of freedom of carriers instead of electrons’ charge for storing and processing data. Either by using spins alone or by adding the spin degrees of freedom to the more established semiconductor technology, it is possible to enhance the functionality of the device greatly. In this thesis, two major things have been done. In part one, after studying literature reviews which were done on spin transistors, magnetic bipolar transistor models are proposed, Three quite different magnetic bipolar transistors are developed by incorporating magnetic impurities in all three regions. And the energy band edges of semiconductor device in the presence of magnetic impurities are calculated. In part two, the proposed spin transistors models are validated by employing on some application areas (Cascaded amplifier). The performances of magnetic bipolar transistors (i.e., using one of the models of spin transistors and the proposed ones) for multistage amplifiers are analyzed. In order to simplify the equivalent circuit for AC analysis, simplified re model for low frequency is used. And hybrid-π model is used for high frequency. Since each parameters in re model and hybrid-π model are function of spin polarization of carriers, the equivalent circuit models used in this thesis work quite well for spin based transistor. In this thesis it is able to come up with quite different types of magnetic bipolar transistors in which spin of carriers are the main controlling inputs. It is shown that the device’s parameters are function of the spin of electrons and holes, and the injected spin electrons in the emitter and collector. Contrary to the conventional bipolar transistor, the magnetic bipolar transistor models are capable of controlling current amplification factor and the density of minority of carries through spins of electrons and holes. As a result, the performances of cascaded amplifier are improved compared to the performances of the conventional transistor.
Design and Simulation of Front End 3-in-1 EEG, ECG, EMG Bio-Potential Signal Acquisition System
(Addis Ababa University, 2020-06) Yonas, Worede; Daniel, Dilbie (Mr.)
The last couple of years have given birth to meticulously mapped and innovative solutions in regards to product as well as research of medical analysis tools and diagnostic equipment. The industry has shown a major transformation on the general process of diagnosis tools providing flexibility and enhanced accuracy. However, despite the astonishing progress of the bio-medical industry, the status of medical provision is still a concern in third world countries. The inaccessibility and unaffordability of medical equipment in such countries needs immediate attention as many people fall prey to this problem which can be solved through the provision of a supplementary solution that can aid the process of preliminary diagnosis. In this thesis, the design of a front-end system for EEG, ECG and EMG signal acquisition is done. The design addresses the problem of medical provision in under developed nations by providing a supplementary hardware that is portable making it cost-efficient and readily available. Moreover, it extends the research aspect in the area through the combination of a 3-in-1 signal acquisition hardware and optimizing the design in regards to performance, complexity and scalability. Owing to the fact that the signals operated by the hardware are very weak in nature, the utilization of low noise amplifiers with very high common-mode rejection ratio and gain adjustment is critical. Moreover, the implementation of analog-to-digital conversion needs a thorough analysis in regards to the architecture, resolution and area of application. Accordingly, the design in this thesis is specifically done so as to improve the performance in regards to noise cancellation, minimization of filter circuitry, number of channels and overall circuit complexity. Verification of the design is done with the co-simulation of PSPICE and SIMULINK. The simulation is carried out for individual cases of EEG, EMG and ECG application by using physiological signals of patients from PhysioNet.org through the addition of noise signals to mimic actual physical application of the hardware. Furthermore, the output is analyzed and compared with existing products and previous researches in the area which yielded a 21% improvement in common-mode rejection ratio and a 33% increase in channel capacity.
Study and Analysis of Smart Meter in Power Quality Management and Real Time Monitoring
(Addis Ababa University, 2020-12) Srash, Sendekie; Mohammed, Abdo (PhD)
Power Quality is an area of serious concern for end users due to the frequency of power quality issues and their financial impact. In this context, real -time power quality monitoring needed so as to detect power quality problems and take control action within right time at right place. Utilities are already installing systems to monitor power quality in the distribution system. The equipment used is mostly power quality monitors which have the capability of measuring all the needed parameters specified by the power quality norms. But the price of these instruments dictates that monitoring of all the points in the distribution network with these instruments is from a techno-economic point of view not feasible, especially for developing country. Therefore, utilizing smart meter devices installed in all points of distribution network to gather more accurate data about power quality. In this thesis real-time power quality monitoring and enhancement role of smart meter is presented. To this end, this thesis proposes single phase smart electricity meter based on Arduino Uno and GSM module. The proposed meter was simulated using proteus software and the results of simulation tests of power quality monitoring and enhancement capability of a proposed smart meter are analyzed. The performance of the system measurement is verified based on absolute percentage error (APE) and shown the results to be appropriate. Accuracy of measurement for RMS value of voltage and current, frequency variation, power factor, active power, energy consumption, and supply voltage total harmonics distortion was found less 1% error. Necessary data sent to customers via GSM was tested with help of virtual terminal. Furthermore, it was found that power quality enhanced and consumption of electricity becomes much more efficient (12% increment) by using dynamic power factor correction scheme integrated in smart meter and applying capacitors for the correction of power factor. Real-time power factor monitoring was sophisticated and thyristor switch for capacitor connection without mains supply distortion and delay free. Continuous real-time monitoring capability of meter performance tested over one hour with standard PQ data aggregation time interval.
Analysis of the Effect of Presence of Magnetic Field in Photon-electron Interface
(Addis Ababa University, 2021-11) Alema, Abraha; Getachew, Alemu (PhD)
Electronics played a great role in storing, computing, and transmitting data. However, electronics had certain limitations in bandwidth, speed, power consumption, and electromagnetic interfering. Conversely, photonic provides advantages like large bandwidth, lower power consumption, and immune to electromagnetic interference. Therefore, to overcome the electronics limitations, electronics and photonics integration developed. Despite many advantages of the integration of electronics and photonics, the presence of an external magnetic field in photon-electron interfaces influences the performances of lasers and photodiodes. Those effects are well studied when lasers and photodiodes are separately subjected to the magnetic field in previous studies. However, the difference in the magnetic field effects on the output signal when both transducers are concurrently exposed to the field needs further study. Additionally, the influence of change in input signal frequency to the magnetic field effect on output signal when laser and photodiode are separately and simultaneously exposed also needs further study. To demonstrate the difference in magnetic field effect on the output signal when the frequency of input signal varies as well as both laser and photodiode concurrently exposed to magnetic field relative to separately subjected; experimental setup was prepared in the laboratory by connecting VCSEL and PIN photodiode with other devices. Then experiments were conducted at around room temperature. During experimentation, both transducers were individually and concurrently exposed to the static magnetic field oriented B//n and B┴n, at 3 kHz & 10 kHz. Then output voltage was measured and recorded at 0, 400, 600, 800, and 1000mT. The results were compared based on the rate of change in output voltage at different magnetic flux densities and frequencies. The magnetic field effect on output signal was found higher at 3 kHz compared to at 10 kHz for both VCSEL and PIN photodiode individually and concurrently exposed. Additionally, the comparisons made at a fixed frequency showed that the magnetic field effect on output signal was much higher when VCSEL and PIN photodiode concurrently exposed relative to individually exposed.
Image Deblurring with Compressive Sensing
(Addis Ababa University, 2021-12) Rahel, Berhanu; Fitsum, Assamnew (PhD)
Compressive sensing is a technique which enables recovery of signals that are represented by an underdetermined system of equations. Such a recovery of an original signal is made possible if the samples are represented in a sparse manner provided an appropriate measuring matrix is used for the modeled system. Blurred images are examples of signals that are sparse especially in transform domains. Different researches have been done to show the possibility of recovering blurred images that use sparse representation of transform domains by applying compressive sensing. In this thesis, however, a model has been used that doesn’t require transforming into other domains. In addition, a box-wise approach has been used that derives the underdetermined system matrix from 7x7 segmented boxes of the blurred image. Then compressive sensing algorithms are used to recover the whole image iteratively. This method is shown to have a much better computational complexity, for example, than the traditional Lucy-Richardson deblurring but it has limitations due to approximations used in the 7x7 boxes during modeling. Thus, with this improved computational complexity, the study provides an initial platform to deblur images using box-wise method and compressive sensing theories.
Power Consumption Reduction and User Satisfaction Using Office Task Tailored Automatic Lighting System with Manual Controllability
(Addis Ababa University, 2023-07) Sosina Abiyot; Nebyu Yonas (Mr.)
Lighting that is artificial represents a substantial portion of international electrical power consumption. This high power consumption affects the cost of the power. In work places and offices there is fixed light intensity, mainly in Ethiopia. This fixed light intensity affects the health and comfort of workers in addition to high power consumption. To minimize these problems dimmable or variable light intensity is required. Light dimming can be attained by adjusting the voltage or current which gets to the LED lamp. In this research paper light intensity controller automatically using MAX44009 sensor and manually using android devices to control light intensity via Bluetooth was designed, to satisfy users and the amount of the reduced power is calculated and analyzed but not measured due to lack of proposed materials. The light intensity can be controlled automatically using the MAX44009 sensor when this sensor senses the surrounding light intensity and sends a digital I2C signal into the microcontroller. This microcontroller board, in this research, is Arduino Uno, processes the input data from the sensor and decides to adjust the LED lamp brightness. This system is automatic and users cannot interact with it if they want to adjust the brightness. To overcome this problem there is an additional method to control light intensity manually. Controlling light intensity can be done via Bluetooth. To achieve this system android application that can interact with the Bluetooth module and microcontroller was developed. After developing these two methods independently, they are integrated as one system so that the user can adjust the brightness when he wants to create comfortable environment, or else it can be adjusted automatically to reduce power consumption.
Implementation of the Programmable Memristor based – Long Short Term Memory (LSTM) Circuit for Time Series Prediction
(Addis Ababa University, 2024-08) Abrham Ayal; Fetene Mulugeta (PhD)
Recent advancements in recurrent deep neural networks with Long Short-Term Memory (LSTM) units have resulted in significant technological advancements in artificial intelligence. Recurrent Neural Network (RNN) and LSTM analysis of the time-series data enables us to recognise long-term trends and make predictions that can improve our way of life. State-of-the-art LSTM models with massively higher ambiguity and a large number of parameters, on the other hand, have a significant advantage. Previously, they tried to solve the time series prediction problems using LSTM based architecture, but the method to solve the problems is more complex, has less accuracy, limited memory capacity, data communication bandwidth and takes high power consumption. This work mainly focused on the implementation of already trained LSTM neural network and fully functional programmable memristor-based LSTM in analog circuitry for the solving time series prediction with increased the performance and to enhance power consumption of the system. Using the voltage-based memristive circuit on the LT-spice circuit simulator and machine learning on python programming with in the combination of the activation function, and multiplier describe the time series prediction of the LSTM architecture. Each state will have some noise, and as the noise level increases, so does the prediction accuracy in analog hardware. As a result we have get results using machine learning based LSTM and programmable memristor based LSTM of the MSE and RMSE value reduced by an average of 0.0101 and 0.100 to 0.00915 and 0.095 respectively. We use real-world regression and prediction problems to demonstrate the capabilities of our system, and the programmable memristor LSTM is a promising easy-configuration, low-power, and low-latency hardware platform for edge inference.

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