A modified varactor device using Barium Strontium Titanate (Ba0.6Sr0.4TiO3) thin films for low lo... more A modified varactor device using Barium Strontium Titanate (Ba0.6Sr0.4TiO3) thin films for low loss millimeter wave frequency applications is demonstrated in this paper. MIM (Metal Insulator Metal) varactor devices with splits in the signal line presented in this work has >7:1 tunability for 35-50 GHz frequency range. The overall capacitance of the device changes from 0.19 pF to 0.025 pF with 0V-10V DC bias voltage applied. The device has very low insertion loss of 0.9 dB with 10 V DC bias voltage applied at 50 GHz.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
A simple passive capacitance model has been optimized to predict breakdown in a stacked SOI FET. ... more A simple passive capacitance model has been optimized to predict breakdown in a stacked SOI FET. Specifically, as the number of FETs in a switch increases, an equivalent increase in breakdown is not seen in hardware; instead, the breakdown performance saturates as the number of stacks in the FET increases. This phenomenon is not predicted by the FET foundry model. This work is focused on FETs for RF switches in flip chip topologies. As a result of this work, the different components that contribute to off-state capacitances were also described which is important for model development and accuracy.
Due to their excellent electrical, optical, and mechanical properties, nanosized single wall carb... more Due to their excellent electrical, optical, and mechanical properties, nanosized single wall carbon nanotubes (SWNTs) have attracted significant attention as a transducing element in nano-bio sensor research. Controlled assembly, device fabrication, and bio-functionalization of the SWNTs are crucial in creating the sensors. In this study, working biosensor platforms were created using dielectrophoretic assembly of single wall carbon nanotubes (SWNTs) as a bridge between two gold electrodes. SWNTs in a commercial SDS surfactant solution were dispensed in the gap between the two gold electrodes, followed by applying an ac voltage across the two electrodes. The dielectrophoresis aligns the CNTs and forms a bridge between the two electrodes. A copious washing and a subsequent annealing of the devices at 200 ᵒC remove the surfactants and create an excellent semiconducting (p-type) bridge between the two electrodes. A liquid gated field effect transistor (LGFET) was built using DI water as the gate dielectric and the SWNT bridge as the channel. Negative gate voltages of the FET increased the drain current and applying a positive gate voltage of +0.5V depleted the channel of charges and turned the device off. The biosensor was verified using both the two terminal and three terminal devices. Genomic salmon DNA dissolved in DI water was applied on the SWNT bridge in both type of devices. In the two terminal device, the conductance of the bridge dropped by 65x after the binding of the DNA. In the LGFET, the transconductance of the device decreased 2X after the binding of the DNA. The binding of the DNA also suppressed hysteresis in the Drain Current vs Gate Voltage characteristics of the LGFET.
In this paper, parallel plate varactor based phase shifter circuits using Barium Strontium Titana... more In this paper, parallel plate varactor based phase shifter circuits using Barium Strontium Titanate (BST) thin films are presented. A cascade of 10, 15 and 20 parallel plate varactors were able to produce (150°, 258°, 297°), (218°, 381°,443°) and (227°, 402°, 464°) phase shift at (5, 10, 12 GHz) respectively. The 360° phase shift is achieved with small device size, low bias voltages (0-8 V), low leakage currents, low insertion loss and high figure of merit (FOM). FOM of 40, 33, 24 Degrees/dB is achieved with 10, 15 and 20 shunt varactors at 12 GHz respectively. The proposed circuit is very easy to fabricate which uses a CPW transmission line configuration and can be easily integrated with other circuits on chip.
.................................................................................................... more .............................................................................................................. iv DEDICATION ............................................................................................................ vi ACKNOWLEDGEMENTS .......................................................................................... vii LIST OF FIGURES ................................................................................................... xiii LIST OF TABLES ................................................................................................... xviii CHAPTER 1: INTRODUCTION .................................................................................. 1 1.1 Background ............................................................................................... 1 1.2 Scope............................................................................... ............. 5 1.3 Outline ...................................................................................................... 6 CHAPTER 2: FILTERS ............................................................................................... 7 2.
A modified design of band stop filters using unconventional defected ground structures (DGS) is p... more A modified design of band stop filters using unconventional defected ground structures (DGS) is presented. The new proposed structures have conventional dumbbell DGS and spiral DGS integrated with U-slots. These microstrip structures provide high selectivity and Q-factor. By integrating the U-slot to the conventional structures, the overall capacitance and inductance increase which results in shift of resonance frequency from3.434 GHz to2.323 GHz for modified dumbbell and from 1.818 GHz to 1.702 GHz for modified spiral structure. Sharp transition is achieved from pass band to stop band and reduced ripples in the pass band for the new proposed DGS while the DGS sizes remain the same. The proposed designs were fabricated and tested on a dielectric substrate with dielectric permittivity of 10. V
2019 IEEE National Aerospace and Electronics Conference (NAECON), 2019
In this paper, parallel plate varactor based phase shifter circuits using Barium Strontium Titana... more In this paper, parallel plate varactor based phase shifter circuits using Barium Strontium Titanate (BST) thin films are presented. A cascade of 10, 15 and 20 parallel plate varactors were able to produce (150°, 258°, 297°), (218°, 381°,443°) and (227°, 402°, 464°) phase shift at (5, 10, 12 GHz) respectively. The 360° phase shift is achieved with small device size, low bias voltages (0-8 V), low leakage currents, low insertion loss and high figure of merit (FOM). FOM of 40, 33, 24 Degrees/dB is achieved with 10, 15 and 20 shunt varactors at 12 GHz respectively. The proposed circuit is very easy to fabricate which uses a CPW transmission line configuration and can be easily integrated with other circuits on chip.
In this thesis, modified design of band stop filters using defected ground structures have been p... more In this thesis, modified design of band stop filters using defected ground structures have been proposed. The new proposed structures have conventional dumbbell DGS integrated with U-slot and the conventional spiral DGS integrated with U-slot both designed using microstrip lines. These structures provide high Q-factor with low insertion loss (below 1dB) in the pass band. By adding the U-slot to the conventional structures, the overall capacitance and inductance are increased which results in low resonance frequency of 1.4GHz with a notch depth of-39.13dB for dumbbell-slot when compared to 2.6 GHz with a notch depth of-32.21dB for conventional dumbbell DGS. The resonance frequency is 1.2GHz with a notch depth of-35.4 dB for spiral-slot when compared to 1.4GHz and a notch depth of-14.6dB for conventional spiral DGS. Sharp transition is achieved from pass band to stop band for the new proposed DGS while the DGS sizes remained v the same. The proposed designs were fabricated for a dielectric substrate with a dielectric constant, εr of 10. vi Dedicated to my parents and my brother vii ACKNOWLEDGEMENTS First, I would like to thank Dr.Guru Subramanyam, my advisor who has been very patient and supported me since the day I have joined University of Dayton. He had always given me the freedom to work on my own pace and my own style which made me very comfortable when I was fully loaded with other tasks. I thank him for all his support and encouragement he gave me throughout my program. I would also like to thank Dr. Sunil Kumar Khah, who was a visiting professor from India. He was the one who introduced Defected Ground Structures to me, and helped me to gain good knowledge in this topic. He also helped me with learning AWR tool and introduced me to Dustin Brown while he was leaving back to India. Dustin, who is now Dr. Brown, was really the best team member I ever had in my life. He had really helped me a lot with all kinds of problems I had when I started my thesis. He never hesitated to share his knowledge with others which was really helpful for a beginner like me when I newly joined this lab. I would also like to thank Dr. Monish Chatterjee, who is like my mentor. He always helped me boost my confidence levels whenever I felt it was necessary. I still remember my first master's class Digital Communications which was taught by him in spring 2013, during the course I viii got an opportunity to learn a lot from him. I would like to thank him for being one of my committee members. I would also like to thank Dr. Weisong Wang for being my committee member and reviewing my work and guiding me whenever I needed help. I would also like to thank Dr.Eunsung shin, Wang Shu, Hailing Yue, Kuan-Chan Pan, Ayesha Zaman for the support they gave me.
A modified varactor device using Barium Strontium Titanate (Ba0.6Sr0.4TiO3) thin films for low lo... more A modified varactor device using Barium Strontium Titanate (Ba0.6Sr0.4TiO3) thin films for low loss millimeter wave frequency applications is demonstrated in this paper. MIM (Metal Insulator Metal) varactor devices with splits in the signal line presented in this work has >7:1 tunability for 35-50 GHz frequency range. The overall capacitance of the device changes from 0.19 pF to 0.025 pF with 0V-10V DC bias voltage applied. The device has very low insertion loss of 0.9 dB with 10 V DC bias voltage applied at 50 GHz.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
A simple passive capacitance model has been optimized to predict breakdown in a stacked SOI FET. ... more A simple passive capacitance model has been optimized to predict breakdown in a stacked SOI FET. Specifically, as the number of FETs in a switch increases, an equivalent increase in breakdown is not seen in hardware; instead, the breakdown performance saturates as the number of stacks in the FET increases. This phenomenon is not predicted by the FET foundry model. This work is focused on FETs for RF switches in flip chip topologies. As a result of this work, the different components that contribute to off-state capacitances were also described which is important for model development and accuracy.
Due to their excellent electrical, optical, and mechanical properties, nanosized single wall carb... more Due to their excellent electrical, optical, and mechanical properties, nanosized single wall carbon nanotubes (SWNTs) have attracted significant attention as a transducing element in nano-bio sensor research. Controlled assembly, device fabrication, and bio-functionalization of the SWNTs are crucial in creating the sensors. In this study, working biosensor platforms were created using dielectrophoretic assembly of single wall carbon nanotubes (SWNTs) as a bridge between two gold electrodes. SWNTs in a commercial SDS surfactant solution were dispensed in the gap between the two gold electrodes, followed by applying an ac voltage across the two electrodes. The dielectrophoresis aligns the CNTs and forms a bridge between the two electrodes. A copious washing and a subsequent annealing of the devices at 200 ᵒC remove the surfactants and create an excellent semiconducting (p-type) bridge between the two electrodes. A liquid gated field effect transistor (LGFET) was built using DI water as the gate dielectric and the SWNT bridge as the channel. Negative gate voltages of the FET increased the drain current and applying a positive gate voltage of +0.5V depleted the channel of charges and turned the device off. The biosensor was verified using both the two terminal and three terminal devices. Genomic salmon DNA dissolved in DI water was applied on the SWNT bridge in both type of devices. In the two terminal device, the conductance of the bridge dropped by 65x after the binding of the DNA. In the LGFET, the transconductance of the device decreased 2X after the binding of the DNA. The binding of the DNA also suppressed hysteresis in the Drain Current vs Gate Voltage characteristics of the LGFET.
In this paper, parallel plate varactor based phase shifter circuits using Barium Strontium Titana... more In this paper, parallel plate varactor based phase shifter circuits using Barium Strontium Titanate (BST) thin films are presented. A cascade of 10, 15 and 20 parallel plate varactors were able to produce (150°, 258°, 297°), (218°, 381°,443°) and (227°, 402°, 464°) phase shift at (5, 10, 12 GHz) respectively. The 360° phase shift is achieved with small device size, low bias voltages (0-8 V), low leakage currents, low insertion loss and high figure of merit (FOM). FOM of 40, 33, 24 Degrees/dB is achieved with 10, 15 and 20 shunt varactors at 12 GHz respectively. The proposed circuit is very easy to fabricate which uses a CPW transmission line configuration and can be easily integrated with other circuits on chip.
.................................................................................................... more .............................................................................................................. iv DEDICATION ............................................................................................................ vi ACKNOWLEDGEMENTS .......................................................................................... vii LIST OF FIGURES ................................................................................................... xiii LIST OF TABLES ................................................................................................... xviii CHAPTER 1: INTRODUCTION .................................................................................. 1 1.1 Background ............................................................................................... 1 1.2 Scope............................................................................... ............. 5 1.3 Outline ...................................................................................................... 6 CHAPTER 2: FILTERS ............................................................................................... 7 2.
A modified design of band stop filters using unconventional defected ground structures (DGS) is p... more A modified design of band stop filters using unconventional defected ground structures (DGS) is presented. The new proposed structures have conventional dumbbell DGS and spiral DGS integrated with U-slots. These microstrip structures provide high selectivity and Q-factor. By integrating the U-slot to the conventional structures, the overall capacitance and inductance increase which results in shift of resonance frequency from3.434 GHz to2.323 GHz for modified dumbbell and from 1.818 GHz to 1.702 GHz for modified spiral structure. Sharp transition is achieved from pass band to stop band and reduced ripples in the pass band for the new proposed DGS while the DGS sizes remain the same. The proposed designs were fabricated and tested on a dielectric substrate with dielectric permittivity of 10. V
2019 IEEE National Aerospace and Electronics Conference (NAECON), 2019
In this paper, parallel plate varactor based phase shifter circuits using Barium Strontium Titana... more In this paper, parallel plate varactor based phase shifter circuits using Barium Strontium Titanate (BST) thin films are presented. A cascade of 10, 15 and 20 parallel plate varactors were able to produce (150°, 258°, 297°), (218°, 381°,443°) and (227°, 402°, 464°) phase shift at (5, 10, 12 GHz) respectively. The 360° phase shift is achieved with small device size, low bias voltages (0-8 V), low leakage currents, low insertion loss and high figure of merit (FOM). FOM of 40, 33, 24 Degrees/dB is achieved with 10, 15 and 20 shunt varactors at 12 GHz respectively. The proposed circuit is very easy to fabricate which uses a CPW transmission line configuration and can be easily integrated with other circuits on chip.
In this thesis, modified design of band stop filters using defected ground structures have been p... more In this thesis, modified design of band stop filters using defected ground structures have been proposed. The new proposed structures have conventional dumbbell DGS integrated with U-slot and the conventional spiral DGS integrated with U-slot both designed using microstrip lines. These structures provide high Q-factor with low insertion loss (below 1dB) in the pass band. By adding the U-slot to the conventional structures, the overall capacitance and inductance are increased which results in low resonance frequency of 1.4GHz with a notch depth of-39.13dB for dumbbell-slot when compared to 2.6 GHz with a notch depth of-32.21dB for conventional dumbbell DGS. The resonance frequency is 1.2GHz with a notch depth of-35.4 dB for spiral-slot when compared to 1.4GHz and a notch depth of-14.6dB for conventional spiral DGS. Sharp transition is achieved from pass band to stop band for the new proposed DGS while the DGS sizes remained v the same. The proposed designs were fabricated for a dielectric substrate with a dielectric constant, εr of 10. vi Dedicated to my parents and my brother vii ACKNOWLEDGEMENTS First, I would like to thank Dr.Guru Subramanyam, my advisor who has been very patient and supported me since the day I have joined University of Dayton. He had always given me the freedom to work on my own pace and my own style which made me very comfortable when I was fully loaded with other tasks. I thank him for all his support and encouragement he gave me throughout my program. I would also like to thank Dr. Sunil Kumar Khah, who was a visiting professor from India. He was the one who introduced Defected Ground Structures to me, and helped me to gain good knowledge in this topic. He also helped me with learning AWR tool and introduced me to Dustin Brown while he was leaving back to India. Dustin, who is now Dr. Brown, was really the best team member I ever had in my life. He had really helped me a lot with all kinds of problems I had when I started my thesis. He never hesitated to share his knowledge with others which was really helpful for a beginner like me when I newly joined this lab. I would also like to thank Dr. Monish Chatterjee, who is like my mentor. He always helped me boost my confidence levels whenever I felt it was necessary. I still remember my first master's class Digital Communications which was taught by him in spring 2013, during the course I viii got an opportunity to learn a lot from him. I would like to thank him for being one of my committee members. I would also like to thank Dr. Weisong Wang for being my committee member and reviewing my work and guiding me whenever I needed help. I would also like to thank Dr.Eunsung shin, Wang Shu, Hailing Yue, Kuan-Chan Pan, Ayesha Zaman for the support they gave me.
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