Matching Items (4)
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- All Subjects: DC-to-DC converters
- Creators: Seo, Jae-Sun
Description
Switching Converters (SC) are an excellent choice for hand held devices due to their high power conversion efficiency. However, they suffer from two major drawbacks. The first drawback is that their dynamic response is sensitive to variations in inductor (L) and capacitor (C) values. A cost effective solution is implemented by designing a programmable digital controller. Despite variations in L and C values, the target dynamic response can be achieved by computing and programming the filter coefficients for a particular L and C. Besides, digital controllers have higher immunity to environmental changes such as temperature and aging of components. The second drawback of SCs is their poor efficiency during low load conditions if operated in Pulse Width Modulation (PWM) mode. However, if operated in Pulse Frequency Modulation (PFM) mode, better efficiency numbers can be achieved. A mostly-digital way of detecting PFM mode is implemented. Besides, a slow serial interface to program the chip, and a high speed serial interface to characterize mixed signal blocks as well as to ship data in or out for debug purposes are designed. The chip is taped out in 0.18µm IBM's radiation hardened CMOS process technology. A test board is built with the chip, external power FETs and driver IC. At the time of this writing, PWM operation, PFM detection, transitions between PWM and PFM, and both serial interfaces are validated on the test board.
ContributorsMumma Reddy, Abhiram (Author) / Bakkaloglu, Bertan (Thesis advisor) / Ogras, Umit Y. (Committee member) / Seo, Jae-Sun (Committee member) / Arizona State University (Publisher)
Created2014
Description
State of art modern System-On-Chip architectures often require very low noise supplies without overhead on high efficiencies. Low noise supplies are especially important in noise sensitive analog blocks such as high precision Analog-to-Digital Converters, Phase Locked Loops etc., and analog signal processing blocks. Switching regulators, while providing high efficiency power conversion suffer from inherent ripple on their output. A typical solution for high efficiency low noise supply is to cascade switching regulators with Low Dropout linear regulators (LDO) which generate inherently quiet supplies. The switching frequencies of switching regulators keep scaling to higher values in order to reduce the sizes of the passive inductor and capacitors at the output of switching regulators. This poses a challenge for existing solutions of switching regulators followed by LDO since the Power Supply Rejection (PSR) of LDOs are band-limited. In order to achieve high PSR over a wideband, the penalty would be to increase the quiescent power consumed to increase the bandwidth of the LDO and increase in solution area of the LDO. Hence, an alternative to the existing approach is required which improves the ripple cancellation at the output of switching regulator while overcoming the deficiencies of the LDO.
This research focuses on developing an innovative technique to cancel the ripple at the output of switching regulator which is scalable across a wide range of switching frequencies. The proposed technique consists of a primary ripple canceller and an auxiliary ripple canceller, both of which facilitate in the generation of a quiet supply and help to attenuate the ripple at the output of buck converter by over 22dB. These techniques can be applied to any DC-DC converter and are scalable across frequency, load current, output voltage as compared to LDO without significant overhead on efficiency or area. The proposed technique also presents a fully integrated solution without the need of additional off-chip components which, considering the push for full-integration of Power Management Integrated Circuits, is a big advantage over using LDOs.
This research focuses on developing an innovative technique to cancel the ripple at the output of switching regulator which is scalable across a wide range of switching frequencies. The proposed technique consists of a primary ripple canceller and an auxiliary ripple canceller, both of which facilitate in the generation of a quiet supply and help to attenuate the ripple at the output of buck converter by over 22dB. These techniques can be applied to any DC-DC converter and are scalable across frequency, load current, output voltage as compared to LDO without significant overhead on efficiency or area. The proposed technique also presents a fully integrated solution without the need of additional off-chip components which, considering the push for full-integration of Power Management Integrated Circuits, is a big advantage over using LDOs.
ContributorsJoshi, Kishan (Author) / Bakkaloglu, Bertan (Thesis advisor) / Garrity, Douglas (Committee member) / Seo, Jae-Sun (Committee member) / Arizona State University (Publisher)
Created2016
Description
The information era has brought about many technological advancements in the past
few decades, and that has led to an exponential increase in the creation of digital images and
videos. Constantly, all digital images go through some image processing algorithm for
various reasons like compression, transmission, storage, etc. There is data loss during this
process which leaves us with a degraded image. Hence, to ensure minimal degradation of
images, the requirement for quality assessment has become mandatory. Image Quality
Assessment (IQA) has been researched and developed over the last several decades to
predict the quality score in a manner that agrees with human judgments of quality. Modern
image quality assessment (IQA) algorithms are quite effective at prediction accuracy, and
their development has not focused on improving computational performance. The existing
serial implementation requires a relatively large run-time on the order of seconds for a single
frame. Hardware acceleration using Field programmable gate arrays (FPGAs) provides
reconfigurable computing fabric that can be tailored for a broad range of applications.
Usually, programming FPGAs has required expertise in hardware descriptive languages
(HDLs) or high-level synthesis (HLS) tool. OpenCL is an open standard for cross-platform,
parallel programming of heterogeneous systems along with Altera OpenCL SDK, enabling
developers to use FPGA's potential without extensive hardware knowledge. Hence, this
thesis focuses on accelerating the computationally intensive part of the most apparent
distortion (MAD) algorithm on FPGA using OpenCL. The results are compared with CPU
implementation to evaluate performance and efficiency gains.
few decades, and that has led to an exponential increase in the creation of digital images and
videos. Constantly, all digital images go through some image processing algorithm for
various reasons like compression, transmission, storage, etc. There is data loss during this
process which leaves us with a degraded image. Hence, to ensure minimal degradation of
images, the requirement for quality assessment has become mandatory. Image Quality
Assessment (IQA) has been researched and developed over the last several decades to
predict the quality score in a manner that agrees with human judgments of quality. Modern
image quality assessment (IQA) algorithms are quite effective at prediction accuracy, and
their development has not focused on improving computational performance. The existing
serial implementation requires a relatively large run-time on the order of seconds for a single
frame. Hardware acceleration using Field programmable gate arrays (FPGAs) provides
reconfigurable computing fabric that can be tailored for a broad range of applications.
Usually, programming FPGAs has required expertise in hardware descriptive languages
(HDLs) or high-level synthesis (HLS) tool. OpenCL is an open standard for cross-platform,
parallel programming of heterogeneous systems along with Altera OpenCL SDK, enabling
developers to use FPGA's potential without extensive hardware knowledge. Hence, this
thesis focuses on accelerating the computationally intensive part of the most apparent
distortion (MAD) algorithm on FPGA using OpenCL. The results are compared with CPU
implementation to evaluate performance and efficiency gains.
ContributorsGunavelu Mohan, Aswin (Author) / Sohoni, Sohum (Thesis advisor) / Ren, Fengbo (Thesis advisor) / Seo, Jae-Sun (Committee member) / Arizona State University (Publisher)
Created2017
Description
Switching regulator has several advantages over linear regulator, but the drawback of switching regulator is ripple voltage on output. Previously people use LDO following a buck converter and multi-phase buck converter to reduce the output voltage ripple. However, these two solutions also have obvious drawbacks and limitations.
In this thesis, a novel mixed signal adaptive ripple cancellation technique is presented. The idea is to generate an artificial ripple current with the same amplitude as inductor current ripple but opposite phase that has high linearity tracking behavior. To generate the artificial triangular current, duty cycle information and inductor current ripple amplitude information are needed. By sensing switching node SW, the duty cycle information can be obtained; by using feedback the amplitude of the artificial ripple current can be regulated. The artificial ripple current cancels out the inductor current, and results in a very low ripple output current flowing to load. In top level simulation, 19.3dB ripple rejection can be achieved.
In this thesis, a novel mixed signal adaptive ripple cancellation technique is presented. The idea is to generate an artificial ripple current with the same amplitude as inductor current ripple but opposite phase that has high linearity tracking behavior. To generate the artificial triangular current, duty cycle information and inductor current ripple amplitude information are needed. By sensing switching node SW, the duty cycle information can be obtained; by using feedback the amplitude of the artificial ripple current can be regulated. The artificial ripple current cancels out the inductor current, and results in a very low ripple output current flowing to load. In top level simulation, 19.3dB ripple rejection can be achieved.
ContributorsYang, Zhe (Author) / Bakkaloglu, Bertan (Thesis advisor) / Seo, Jae-Sun (Committee member) / Lei, Qin (Committee member) / Arizona State University (Publisher)
Created2016