Matching Items (7)
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- All Subjects: Electrical
- Creators: Ozev, Sule
- Creators: Kitchen, Jennifer
Description
High speed current-steering DACs with high linearity are needed in today's applications such as wired and wireless communications, instrumentation, radar, and other direct digital synthesis (DDS) applications. However, a trade-off exists between the speed and resolution of Nyquist rate current-steering DACs. As the resolution increases, more transistor area is required to meet matching requirements for optimal linearity and thus, the overall speed of the DAC is limited.
In this thesis work, a 12-bit current-steering DAC was designed with current sources scaled below the required matching size to decrease the area and increase the overall speed of the DAC. By scaling the current sources, however, errors due to random mismatch between current sources will arise and additional calibration hardware is necessary to ensure 12-bit linearity. This work presents how to implement a self-calibration DAC that works to fix amplitude errors while maintaining a lower overall area. Additionally, the DAC designed in this thesis investigates the implementation feasibility of a data-interleaved architecture. Data interleaving can increase the total bandwidth of the DACs by 2 with an increase in SQNR by an additional 3 dB.
The final results show that the calibration method can effectively improve the linearity of the DAC. The DAC is able to run up to 400 MSPS frequencies with a 75 dB SFDR performance and above 87 dB SFDR performance at update rates of 200 MSPS.
In this thesis work, a 12-bit current-steering DAC was designed with current sources scaled below the required matching size to decrease the area and increase the overall speed of the DAC. By scaling the current sources, however, errors due to random mismatch between current sources will arise and additional calibration hardware is necessary to ensure 12-bit linearity. This work presents how to implement a self-calibration DAC that works to fix amplitude errors while maintaining a lower overall area. Additionally, the DAC designed in this thesis investigates the implementation feasibility of a data-interleaved architecture. Data interleaving can increase the total bandwidth of the DACs by 2 with an increase in SQNR by an additional 3 dB.
The final results show that the calibration method can effectively improve the linearity of the DAC. The DAC is able to run up to 400 MSPS frequencies with a 75 dB SFDR performance and above 87 dB SFDR performance at update rates of 200 MSPS.
ContributorsJankunas, Benjamin (Author) / Bakkaloglu, Bertan (Thesis advisor) / Kitchen, Jennifer (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2014
Description
The Phoenix CubeSat is a 3U Earth imaging CubeSat which will take infrared (IR) photos of cities in the United Stated to study the Urban Heat Island Effect, (UHI) from low earth orbit (LEO). It has many different components that need to be powered during the life of its mission. The only power source during the mission will be its solar panels. It is difficult to calculate power generation from solar panels by hand because of the different orientations the satellite will be positioned in during orbit; therefore, simulation will be used to produce power generation data. Knowing how much power is generated is integral to balancing the power budget, confirming whether there is enough power for all the components, and knowing whether there will be enough power in the batteries during eclipse. This data will be used to create an optimal design for the Phoenix CubeSat to accomplish its mission.
ContributorsBarakat, Raymond John (Author) / White, Daniel (Thesis director) / Kitchen, Jennifer (Committee member) / Electrical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The Built-In Self-Test for Simultaneous Transmit and Receive (BIST for STAR) will be able to solve the challenges of transmitting and receiving at the same time at the same frequency. One of the major components is the STAR antenna which transmits and receives along the same pathway. The main problem with doing both on the same path is that the transmit signal is usually much stronger in power compared to the received signal. The transmit signal has echoes and leakages that cause self-interference, preventing the received signal from being properly obtained. The solution developed in this project is the BIST component, which will help calculate the functional gain and phase offset of the interference signal and subtract it from the pathway so that the received signal remains. The functions of the proposed circuit board can be modeled in Matlab, where an emulation code generates a random, realistic functional gain and delay for the interference. From the generated values, the BIST for STAR was simulated to output what the measurements would be given the strength of the input signal and a controlled delay. The original Matlab code models an ideal environment directly recalculating the functional gain and phase from the given measurements in a second Matlab script. The actual product will not be ideal; a possible source of error to be considered is the effect of thermal noise. To observe the effect of noise on the BIST for STAR's performance, the Matlab code was expanded upon to include a component for thermal noise, and a method of analyzing the results of the board.
ContributorsLiu, Jennifer Yuan (Author) / Ozev, Sule (Thesis director) / Kozicki, Michael (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The capstone portion of this project was to use the established STaR antennas and add a Built in Self-Test system to ensure the quality of the signals being received. This part of the project required a MatLab simulation to be built, a layout created, and a PCB designed for fabrication. In theory, the test BiST unit will allow the gain and delay of the transmitted signal and then cancel out unneeded interference for the received signal. However, this design required multiple paths to maintain the same lengths to keep the signals in phase for comparison. The purpose of this thesis is to show the potential drop-offs of the quality of the signals from being out of phase due to the wires that should be similar, being off by a certain percentage. This project will calculate the theoretical delay of all wires being out of sync and then add this delay to the established MatLab simulation. This report will show the relationship between the error of the received variables and what the actual generated values. And, the last part of the document will demonstrate the simulation by creating a signal and comparing it to its received counterpart. The end result of the study showed that the percent error between what is seen and what is expected is near insignificant and, hence, not an issue with regards to the quality of the project.
ContributorsSomers, Tyler Scott (Author) / Ozev, Sule (Thesis director) / Kozicki, Michael (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The purpose of the Simultaneous Transmit and Receive Antenna project is to design a test circuit that will allow us to use an antenna to both send out and receive a signal at the same time on the same frequency. The test circuit will generate DC voltage levels that we can use to solve for the gain and delay of the transmit interference, so we will then be able to cancel out the unwanted signal from the received signal. With a theoretically perfect setup, the transmitted signal will be able to be completely isolated from the received signal, leaving us with only what we want at the output. In practice, however, this is not the case. There are many variables that will affect the integrity of the DC output of the test signal. As the output voltage level deviates from its theoretical perfect measurement, the precision to which we are able to solve for the gain and delay values decreases. The focus of this study is to estimate the effect of using a digital measurement tool to measure the output of the test circuit. Assuming a voltmeter with 1 volt full range, simulations were run using measurements stored at different bit resolutions, from 8-bit storage up to 16-bit storage. Since the physical hardware for the Simultaneous Transmit and Receive test circuit is not currently available, these tests were performed with an edited version of the Matlab simulation created for the Senior Design project. The simulation was run 2000 times over each bit resolution to get a wide range of generated values, then the error from each run was analyzed to come to a conclusion on the effect of the digital measurement on the design. The results of these simulations as well as further details of the project and testing are described inside this document.
ContributorsKral, Brandon Michael (Author) / Ozev, Sule (Thesis director) / Kozicki, Michael (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Testing and calibration constitute a significant part of the overall manufacturing cost of microelectromechanical system (MEMS) devices. Developing a low-cost testing and calibration scheme applicable at the user side that ensures the continuous reliability and accuracy is a crucial need. The main purpose of testing is to eliminate defective devices and to verify the qualifications of a product is met. The calibration process for capacitive MEMS devices, for the most part, entails the determination of the mechanical sensitivity. In this work, a physical-stimulus-free built-in-self-test (BIST) integrated circuit (IC) design characterizing the sensitivity of capacitive MEMS accelerometers is presented. The BIST circuity can extract the amplitude and phase response of the acceleration sensor's mechanics under electrical excitation within 0.55% of error with respect to its mechanical sensitivity under the physical stimulus. Sensitivity characterization is performed using a low computation complexity multivariate linear regression model. The BIST circuitry maximizes the use of existing analog and mixed-signal readout signal chain and the host processor core, without the need for computationally expensive Fast Fourier Transform (FFT)-based approaches. The BIST IC is designed and fabricated using the 0.18-µm CMOS technology. The sensor analog front-end and BIST circuitry are integrated with a three-axis, low-g capacitive MEMS accelerometer in a single hermetically sealed package. The BIST circuitry occupies 0.3 mm2 with a total readout IC area of 1.0 mm2 and consumes 8.9 mW during self-test operation.
ContributorsOzel, Muhlis Kenan (Author) / Bakkaloglu, Bertan (Thesis advisor) / Ozev, Sule (Thesis advisor) / Kiaei, Sayfe (Committee member) / Ogras, Umit Y. (Committee member) / Arizona State University (Publisher)
Created2017
Description
Micro Electro Mechanical Systems (MEMS) based accelerometers are one of the most commonly used sensors out there. They are used in devices such as, airbags, smartphones, airplanes, and many more. Although they are very accurate, they degrade with time or get offset due to some damage. To fix this, they must be calibrated again using physical calibration technique, which is an expensive process to conduct. However, these sensors can also be calibrated infield by applying an on-chip electrical stimulus to the sensor. Electrical stimulus-based calibration could bring the cost of testing and calibration significantly down as compared to factory testing. In this thesis, simulations are presented to formulate a statistical prediction model based on an electrical stimulus. Results from two different approaches of electrical calibration have been discussed. A prediction model with a root mean square error of 1% has been presented in this work. Experiments were conducted on commercially available accelerometers to test the techniques used for simulations.
ContributorsBassi, Ishaan (Author) / Ozev, Sule (Thesis advisor) / Christen, Jennifer Blain (Committee member) / Vasileska, Dragica (Committee member) / Arizona State University (Publisher)
Created2020