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(1 - 4 of 4)
- Title
- THE EFFECT OF HOT CARRIER STRESS ON LOW NOISE AMPLIFIER RADIO FREQUENCY PERFORMANCE UNDER WEAK AND STRONG INVERSION.
- Creator
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Shen, Lin, Yuan, Jiann, University of Central Florida
- Abstract / Description
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This thesis work is mainly focused on studying RF performance degradation of a low noise amplifier (LNA) circuit due to hot carrier effect (HCE) in both the weak and strong inversion regions. Since the figures of merit for the RF circuit characterization are gain, noise figure, input, and output matching, the LNA RF performance drift is evaluated in a Cadence SpectreRF simulator subject to these features. This thesis presents hot carrier induced degradation results of an LNA to show that the...
Show moreThis thesis work is mainly focused on studying RF performance degradation of a low noise amplifier (LNA) circuit due to hot carrier effect (HCE) in both the weak and strong inversion regions. Since the figures of merit for the RF circuit characterization are gain, noise figure, input, and output matching, the LNA RF performance drift is evaluated in a Cadence SpectreRF simulator subject to these features. This thesis presents hot carrier induced degradation results of an LNA to show that the HCE phenomenon is one of the serious reliability issues in the aggressively scaled RF CMOS design, especially for long-term operation of these devices. The predicted degradation from simulation results can be used design reliable CMOS RF circuits.
Show less - Date Issued
- 2006
- Identifier
- CFE0000952, ucf:46763
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000952
- Title
- A LOW PHASE NOISE K-BAND OSCILLATOR UTILIZING AN EMBEDDED DIELECTRIC RESONATOR ON MULTILAYER HIGH FREQUENCY LAMINATES.
- Creator
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Subramanian, Ajay, Gong, Xun, University of Central Florida
- Abstract / Description
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K-Band (18 to 26 GHz) dielectric resonator oscillators are typically used as a local oscillator in most K-Band digital transmitter/receiver topologies. Traditionally, the oscillator itself is made up of an active device, a dielectric resonator termination network, and a passive load matching network. The termination network embodies a cylindrical high permittivity dielectric resonator that is coupled on the same plane as a current carrying transmission line. This configuration provides an...
Show moreK-Band (18 to 26 GHz) dielectric resonator oscillators are typically used as a local oscillator in most K-Band digital transmitter/receiver topologies. Traditionally, the oscillator itself is made up of an active device, a dielectric resonator termination network, and a passive load matching network. The termination network embodies a cylindrical high permittivity dielectric resonator that is coupled on the same plane as a current carrying transmission line. This configuration provides an adequate resonance needed for oscillation but has some limitations. In order to provide a high Q resonance the entire oscillator is placed in a metal box to prevent radiation losses. This increases the overall size of the device and makes it difficult to integrate in smaller transceiver topologies. Secondly, a tuning screw is required to help excite the dominant mode of the resonator to achieve the high Q response. This can cause problems in precision due to the mechanical jitter of the screw inherent in mobile devices. By embedding this resonator inside the substrate it is possible to realize a very high Q resonance at a desired frequency and remove the need for a metal cavity and tuning screw. An additional advantage can be seen in terms of overall size reduction of the oscillator circuit. To demonstrate the feasibility of utilizing a dielectric resonator embedded within a substrate, a K-Band oscillator proof of concept has been designed, fabricated, and tested. The oscillator is comprised of a low noise active transistor device, an embedded k-band dielectric resonator and a passive transmission line load network. All elements within the oscillator are optimized to produce a steady oscillation near 20 GHz. Preliminary investigations of a microstrip resonator S-band (2-3 GHz) oscillator are first discussed. Secondly, various challenges in design and fabrication are discussed. Thereafter, simulated and measured results of the embedded DRO structure are presented. Emphasis is placed on output oscillation power and low phase noise. With further development, the entire oscillator can be embedded within the substrate leaving only the active device on the surface. This allows for a considerable reduction in material cost and simple integration with miniaturized digital transmitter/receiver devices.
Show less - Date Issued
- 2008
- Identifier
- CFE0002451, ucf:47718
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002451
- Title
- LOW NOISE AND LOW REPETITION RATE SEMICONDUCTOR-BASED MODE-LOCKED LASERS.
- Creator
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Mnaridis, Dimitrios, Delfyett, Peter, University of Central Florida
- Abstract / Description
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The topic of this dissertation is the development of low repetition rate and low noise semiconductor-based laser sources with a focus on linearly chirped pulse laser sources. In the past decade chirped optical pulses have found a plethora of applications such as photonic analog-to-digital conversion, optical coherence tomography, laser ranging, etc. This dissertation analyzes the aforementioned applications of linearly chirped pulses and their technical requirements, as well as the...
Show moreThe topic of this dissertation is the development of low repetition rate and low noise semiconductor-based laser sources with a focus on linearly chirped pulse laser sources. In the past decade chirped optical pulses have found a plethora of applications such as photonic analog-to-digital conversion, optical coherence tomography, laser ranging, etc. This dissertation analyzes the aforementioned applications of linearly chirped pulses and their technical requirements, as well as the performance of previously demonstrated chirped pulse laser sources. Moreover, the focus is shifted to a specific application of the linearly chirped pulses, time-stretched photonic analog-to-digital conversion (TS ADC). The challenges of surpassing the speeds of current electronic converters are discussed, while the need for low noise linearly chirped pulse lasers becomes apparent for the realization of TS ADC. The experimental research addresses the topic of low noise chirped pulse generation in three distinct ways. First, a chirped pulse (Theta) laser with an intra-cavity Fabry-Perot etalon and a long-term referencing mechanism is developed that results in the reduction of the pulse-to-pulse energy noise. Noise suppression of >15 times is demonstrated. Moreover, an optical frequency comb with spacing equal to the repetition rate (H100 MHz) is generated using the etalon, resulting in the first reported demonstration of a system operating in the sub-GHz regime based on semiconductor gain. The path for the development of the Theta laser was laid by the precise characterization of the etalon used in this laser cavity design. A narrow linewidth laser is used in conjunction with an acousto-optic modulator externally swept for measuring the etalon's free spectral range with a sub-Hz precision, or 10 parts per billion. Furthermore, the measurement of the etalon long-term drift and birefringence lead to the development of a modified intra-cavity Hansch-Couillaud locking mechanism for the Theta laser. Moreover, an external feed-forward system was demonstrated that aimed at increasing the temporal/spectral uniformity of the optical pulses. A complete characterization of the system is demonstrated. On a different series of experiments, the pulses emitted by an ultra-low noise but high repetition rate mode-locked laser were demultiplexed resulting in a low repetition rate pulse train. Experimental investigation of the noise properties of the laser proved that they are preserved during the demultiplexing process. The noise of the electrical gate used in this experiment is also investigated which led into the development of a more profound understanding of the electrical noise of periodical pulses and a mechanism of measuring their noise. The appendices in this dissertation provide additional material used for the realization of the main research focus of the dissertation. Measurements of the group delay of the etalon used in the Theta laser are presented in order to demonstrate the limiting factors for the development of this cavity design. The description of a balancing routine is presented, that was used for expanding the dynamic range of intra-cavity active variable delay. At last, the appendix presents the calculations regarding the contribution of various parameters in the limitations of analog-to-digital conversion.
Show less - Date Issued
- 2011
- Identifier
- CFE0003874, ucf:48741
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003874
- Title
- CMOS RF CITUITS VARIABILITY AND RELIABILITY RESILIENT DESIGN, MODELING, AND SIMULATION.
- Creator
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Liu, Yidong, Yuan, Jiann-Shiun, University of Central Florida
- Abstract / Description
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The work presents a novel voltage biasing design that helps the CMOS RF circuits resilient to variability and reliability. The biasing scheme provides resilience through the threshold voltage (VT) adjustment, and at the mean time it does not degrade the PA performance. Analytical equations are established for sensitivity of the resilient biasing under various scenarios. Power Amplifier (PA) and Low Noise Amplifier (LNA) are investigated case by case through modeling and experiment. PTM 65nm...
Show moreThe work presents a novel voltage biasing design that helps the CMOS RF circuits resilient to variability and reliability. The biasing scheme provides resilience through the threshold voltage (VT) adjustment, and at the mean time it does not degrade the PA performance. Analytical equations are established for sensitivity of the resilient biasing under various scenarios. Power Amplifier (PA) and Low Noise Amplifier (LNA) are investigated case by case through modeling and experiment. PTM 65nm technology is adopted in modeling the transistors within these RF blocks. A traditional class-AB PA with resilient design is compared the same PA without such design in PTM 65nm technology. Analytical equations are established for sensitivity of the resilient biasing under various scenarios. A traditional class-AB PA with resilient design is compared the same PA without such design in PTM 65nm technology. The results show that the biasing design helps improve the robustness of the PA in terms of linear gain, P1dB, Psat, and power added efficiency (PAE). Except for post-fabrication calibration capability, the design reduces the majority performance sensitivity of PA by 50% when subjected to threshold voltage (VT) shift and 25% to electron mobility (¼n) degradation. The impact of degradation mismatches is also investigated. It is observed that the accelerated aging of MOS transistor in the biasing circuit will further reduce the sensitivity of PA. In the study of LNA, a 24 GHz narrow band cascade LNA with adaptive biasing scheme under various aging rate is compared to LNA without such biasing scheme. The modeling and simulation results show that the adaptive substrate biasing reduces the sensitivity of noise figure and minimum noise figure subject to process variation and device aging such as threshold voltage shift and electron mobility degradation. Simulation of different aging rate also shows that the sensitivity of LNA is further reduced with the accelerated aging of the biasing circuit. Thus, for majority RF transceiver circuits, the adaptive body biasing scheme provides overall performance resilience to the device reliability induced degradation. Also the tuning ability designed in RF PA and LNA provides the circuit post-process calibration capability.
Show less - Date Issued
- 2011
- Identifier
- CFE0003595, ucf:48861
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003595
