There is a significant need in recent mobile communication and wireless broadband
systems for high-performance analog-to-digital converters (ADCs) that have wide
bandwidth (BW>5-MHz) and high data rate (>100-Mbps). A delta-sigma ADC is
recognized as a power-efficient ADC architecture when high resolution (>12-b) is
required. This is due to several advantages...
The exponential rate of advances in modern communication devices in the last several years have brought us higher levels of functionality and performance as well as reductions in physical size and power consumption. To continue this rate of advancement, next generation systems require wider bandwidth and higher resolution ADCs. Additionally,...
What are the most effective ways to improve the engineering curriculum? Improvements should result in increased student retention, undergraduates who are more industry-ready and graduates who are better prepared to be leaders. Current research suggests that the best predictor of persistence is a person’s self-efficacy. The focus of this thesis...
Two aspects of ADC system performance are addressed in this work. First, the combination of the ADC and its associated reference are co-designed for an energy constrained remote sensing system. Second, sampling linearity is mathematically analyzed as a function of frequency to provide enhanced understanding into an ADC's requisite sampling...
In recent years, there has been growing interest in both industry and academia to use continuous-time (CT) Δ-Σ A/D converters for wideband wireless and wireline communication applications.
So far no reported CT Δ-Σ A/D modulator achieves 14-bit or higher dynamic range (DR) with more than 2MHz signal bandwidth (equivalently 4MS/s)....
Meadowfoam (Limnanthes R. Br. spp.), a source of C₂₀
and C₂₂ fatty acids, is a new industrial oilseed crop
adapted to the Willamette Valley of Oregon. Increased oil
yield per land area may increase the rate of meadowfoam
commercialization. Using two half-sib L. floccosa x L.
alba lines, 85-765 and...
For today’s ubiquitous portable devices, innovative integrated circuits with high performance
yet very low power are necessary. As these devices are used to communicate and sense real world signals in the environment, analog-to-digital converters (ADC) and systems are the key interface circuits needed to digitize the sensed information and they...
Portable, high power efficiency communication devices is a growing market in the semiconductor industry. Analog-to-digital converters (ADC) are key interface that are used to digitize the sensed information. Recently, digital techniques have been proposed to improve analog building block power efficiency in sub-micron technologies. This research focuses on mixed signal...
An automated method, requiring the fabrication of a small set of test structures, efficiently extracts the coefficients of Z-parameter based macromodels. The extraction approach has been validated for both heavily and lightly doped substrates and can be applied to a variety of technologies. After the parameters of a macromodel have...
As the demand for real-time information in engineering and health care systems keeps increasing, the need for wireless sensor nodes is also continuously increasing. As a result, the cost and effort involved in installing and maintaining batteries to power the numerous sensor nodes is growing exponentially. Providing a cost effective...
Noise-shaping multibit quantizers in a ΔΣ modulator offer extra orders of noise shaping without increasing the loop-filter order and without compromising the stability of the modulator. This dissertation presents two new architectures for improving the overall performance of continuous-time ΔΣ modulators using noise-shaped quantizers.
The first modulator architecture is motivated...
At frequencies exceeding 1-2 GHz, the substrate network models used in substrate coupling simulation must account for the reactive nature of the substrate. Unlike at low frequencies, where the purely resistive substrate models can be validated through DC resistance measurements, these high-frequency models, comprising reactive components, must be validated through...
A differential current-mode track-and-hold (T/H) amplifier is used to sample an analog input signal. A new closed-loop current-mode architecture has been developed that overcomes the stability problems associated with closed-loop architectures. The T/H circuit has been fabricated in a 0.35-μm quad-metal, double-poly CMOS process. The measured total harmonic distortion (THD)...
Analysis of substrate noise coupling has been performed for a 0.18¹m lightly doped silicon germanium BiCMOS process. Techniques to minimize noise coupling in the chip and board design are presented, as well as methods for accurate modeling for substrate noise coupling simulations. Measurements from a test chip were taken to...
A Z-parameter based macromodel for characterizing the substrate noise coupling in a lightly doped substrate at low frequencies has been developed. The model is scalable with contact geometries and separation. The cross-coupling impedance between two contacts is modeled using an improved geometric mean distance formulation. This approach obviates the need...
At frequencies exceeding 1-2 GHz, the reactive nature of a silicon substrate must be accounted in the substrate network models used in substrate coupling simulation. High-frequency substrate models, containing reactive components, must be validated through high-frequency network analyzer measurements. Prior fabricated test fixtures have been modified to enable high-frequency (up...
This dissertation focuses on the analysis, design, and application of inductor-capacitor (LC) oscillators for wireless sensor networks (WSNs).
First an analysis and design optimization approach for enhanced swing, low power CMOS LC oscillators is presented. A phasor based analysis is used for determining the amplitude and phase noise of these...
The substrate noise injected by a stepped buffer circuit into two single-ended 1.5GHz low noise amplifiers is examined for a heavily doped 0.25µm CMOS process. The difference in the LNA noise rejection is characterized as a function of the size and placement of substrate contacts. The use of a resistive...
Harvesting energy from the environment for powering micro-power devices have been increasing in popularity. These types of devices can be used in embedded applications or in sensor networks where battery replacement is impractical. In this dissertation, different methods of energy harvesting from the environment are explored as alternative sources of...
A fully integrated CMOS GPS receiver RF front end optimized for low power operation is presented. The system operates with a supply voltage down to 250 mV. A prototype has been fabricated in a 0.13μm CMOS process and includes a low voltage LNA, quadrature oscillators, and quadrature mixers. It exhibits...
In April of 1997 it was pointed out at an NSF Engineering Education Innovators conference that “… education appears to ignore the need for connections and for integration – which should be at the core of an engineering education.” In order to solve this problem a group named ‘TekBotsTM’ was...
A computationally efficient and accurate substrate noise coupling model for multiple contacts in heavily doped CMOS processes is presented and validated with simulations and experimental data. The model is based on Z parameters that are scalable with contact separation and size. This results in fast extraction of substrate resistances for...
The ability to accurately locate people and objects indoors will enable opportunities for control and automation of indoor environments. Current indoor localization solutions require dedicated hardware which must be custom tailored to each application. There are large technological, societal, and economic benefits in developing a more general purpose system that...
A new method is presented to compress switching information in large digital circuits. This is combined with an efficient approach of generating the noise signatures of cells in a digital library that results in an accurate and efficient approach for estimating the noise generated in digital circuits. This method provides...
This thesis presents the contributions to substrate noise due to supply coupling and the effect of pin parasitics on the substrate noise generated by digital circuits. Various sources of substrate noise and their effect on analog circuits sharing the same substrate are discussed. A simulation approach to isolate the various...
A scalable macromodel for substrate noise coupling in lightly doped substrates with and without a buried layer has been developed. This model is based on Z-parameters and is scalable with contact size and separation. This model requires process dependent parameters that can be extracted easily from a small number of...
In this dissertation, a new Δ∑ A/D converter is presented that is ideally suited for communication applications. It is based on a single-loop single-stage structure, which can realize a high maximum out-of-band quantization noise gain while maintaining stable operation and thus achieve 14-bit resolution at 8 times oversampling. A fifth-order...
This thesis presents a systematic top-down methodology for simulating a phase-locked loop using a macro model in Verilog-A. The macromodel has been used to evaluate the jitter due to supply noise, thermal noise, and ground bounce. The noise simulation with the behavioral model is roughly 310 times faster (best case)...
A variable gain, high linearity, low power baseband filter for WLAN applications is implemented in a 1.5 V 3 V 0.15 μm CMOS process. This fourth-order low-pass filter, which is introduced in the transmit channel as a reconstruction filter between the D/A converter and the mixer, has a measured cut-off...
In 2000 the Electrical and Computer Engineering department at Oregon State University began a new and innovative program named TekBots[superscript TM]. This program was created to solve the problems of students in existing undergraduate engineering education not having sufficient skill when graduating in six program educational objectives; Depth, Breadth, Professionalism,...
The parasitic components of MOS switches at high speeds affect the linearity and resolution of CMOS sample and hold circuits. CCD-based circuit design can offer good performance at high speeds. This thesis presents the design of sample and hold circuits using charge-coupled device structures in a standard CMOS process. Three...
In this thesis, the performance degradation of a phase-locked loop due to substrate noise is examined. A new analytical equivalent circuit model for substrate noise coupling is derived for a heavily doped silicon substrate. The model has been validated with measured data from a 0.35 μm CMOS process. Since the...
A method for improving performance/watt of an embedded single-instruction multiple-data (SIMD) architecture using application-guided a priori scheduling of hardware resources is presented. A multi-core architectural simulator is adopted that accurately estimates power, performance, and utilization of various processor components (logic, interconnect and memory). A greedy search is then performed on...
This thesis focuses on two aspects of oxide-based thin-film transistors (TFTs), contact resistance and instability assessment.
First, determination of the contact resistance of indium tin oxide (ITO) on two wide-band gap semiconductors, zinc oxide (ZnO) and indium gallium oxide (IGO), is attempted and the effects of contact resistance on device...
Analysis and design optimization of enhanced swing, low power CMOS LC oscillators is presented. A phasor analysis based approach for determining the amplitude and phase noise of these oscillators is used. MOSFET operation in cut-off, linear and saturation regions is included. The calculated steady state output amplitude and phase noise...
An ultra low power crystal oscillator that provides a frequency reference for battery
powered timekeeping applications is presented. An amplitude control circuit is employed to ensure that minimum current is consumed. A subthreshold voltage regulator provides a supply voltage for the oscillator with minimum current consumption. The oscillator and regulator...
A fully integrated CMOS latched comparator is presented for use as a wake-up circuit that is attached to an RF energy harvester in a battery free wireless sensor network. The system consumes less than 36nA static current at 20°C and dissipates 2pJ of energy per conversion. The comparator comprises of...
Low energy design techniques for digital circuits are examined to determine their suitability for use in a digital logic controller for wireless sensor network nodes. Transistor level simulations are used to evaluate the techniques and those demonstrating an energy reduction are used to implement a digital logic controller. The digital...
This thesis presents a design-oriented model for lightly doped CMOS substrates. The model predicts the substrate noise coupling between noisy digital and sensitive analog blocks in the early stages of the design. The model scales with the size and separation of these blocks and it is validated with device simulations...
This thesis presents a low-energy application specific digital controller for a battery-free 2.4 GHz wireless sensor network (WSN) node. The digital controller has been designed and fabricated in a standard 0.13 μm CMOS and implements a simple protocol for WSNs. Techniques such as supply voltage reduction and power gating have...
Analog-to-digital converters (ADCs) are the key building block for sensor applications, such as wireless communications and digital electronics. These applications require ADCs to have medium to high accuracy (normally from 10-14 bits) and relatively low signal bandwidth (ranging from 100Hz-150kHz). Since these applications are often powered by batteries, high power...
As the number of autonomous data collection applications keep increasing, the demand for wireless sensor networks (WSNs) has seen explosive growth. In this dissertation, an ultra-low-energy WSN transmitter is developed to reduce the energy consumption of sensor nodes in WSNs. With an ultra-low-energy transceiver, it is possible to eliminate the...
Three types of low noise amplifiers operating at 2.4GHz were designed. They are the commonly used single-ended and differential amplifiers as well as a new quasi-differential amplifier. The substrate noise injected into these amplifiers is examined for both heavily and lightly doped CMOS substrates. For the single-ended amplifier the noise...
Conventional Delta-Sigma analog-to-digital converters (ADCs) utilize operational transconductance amplifiers (OTAs) in their loop filter implementation followed by multi-bit voltage domain quantizers. As CMOS integrated circuit technology scales to smaller geometries, the minimum transistor length and the intrinsic gain of the transistors decrease. Moreover, with process scaling the voltage headroom decreases...
This thesis presents a low power DC-DC converter suitable for harvesting energy from high impedance thermoelectric generators (TEGs) for the use in body powered electronics. The chip has been fabricated in a 130nm CMOS technology. To meet the power demands of body powered networks, a novel dual-path architecture capable of...
A methodology for rapid estimation of substrate noise generated by digital circuitry in mixed-signal circuits is presented. This methodology is incorporated into the Silencer! framework, and also provides for future improvements including pre-layout noise estimation. Measurements of a test chip fabricated in the TSMC o.25[mu]m heavily doped logic process validate...
This thesis presents a Z-parameter based model to predict the substratenoise coupling between two contacts in a heavily doped substrate for frequenciesless than 2 GHz. The empirical model is scalable with contact size and spacingsbetween the contacts and model parameters can be readily extracted from simu-lated or measured data. The...
Delay insensitive asynchronous circuitry provides significant advantages with
respect to substrate noise due to localized switching. The differences between the
substrate noise from NULL Convention Logic (NCL) and traditional Clocked
Boolean Logic (CBL) are described and analyzed based on measured results. A test chip fabricated in the TSMC 0.25 um...
This thesis presents Silencer!, a fully automated, schematic-driven tool for substrate noise coupling simulation and analysis. It has been integrated in the CADENCE DFII environment and seamlessly enables substrate coupling analysis in a standard mixed-signal design flow. Silencer! aids IC designers in the analysis of substrate noise coupling at different...
Efficient methods for simulating the substrate noise generated by complex synchronous and asynchronous digital logic circuits are presented. By simulating digital logic at the gate level, and precharacterizing the gates, the substrate noise generation can be predicted and used in a transistor level simulation of the sensitive analog blocks. This...
An enhanced swing differential Colpitts VCO (ESDC-VCO) dramatically improves
the swing of a Colpitts VCO by allowing the signal to swing below ground and above the
supply voltage. Fabricated in a 1P8M 0.13 um CMOS process, the ESDC-VCO operates
at 4.9GHz with a 0.475-V supply and consumes 2.7mW. The measured...
Wireless sensor networks are becoming important in several monitoring and sensing applications. Ultra low power consumption in the sensor nodes is important for extending the battery life of the nodes. In this dissertation, two low power BFSK receiver architectures are proposed and verified with prototype implementations in silicion.
A 2.4...
In wireless sensor network applications, low-power operation of the wireless receiver is critical. To address this need an ultra-low power Binary Frequency Shift Keying (BFSK) receiver using the super-regenerative architecture is developed.
A prototype receiver is built and tested for operation in the 900 MHz ISM band. Lab measurements show...
The design of mobile wireless devices has always focused on reducing power, area, and cost. This dissertation proposes two techniques that are leveraged to save power and area and therefore cost. The first techniques reduces the noise in the receiver and results in a relaxed power requirement. The second technique...
Modern sensor network applications are often implemented wirelessly in order to lessen installation costs and reduce deployment times. Unfortunately, these wireless sensor network (WSN) nodes must often rely on batteries or energy harvesting techniques in order to sustain their operation and supply the power needed to maintain communication within the...
This thesis presents an automated methodology to calibrate the substrate profile for accurate prediction of substrate parasitics using Green's function based extractors. The technique requires fabrication of only a few test structures and results in an accurate three layered approximation of a heavily doped epitaxial silicon substrate. The obtained substrate...
An analysis of substrate noise coupling in mixed-signal circuits has been performed in the TSMC 0.25 [mu]m lightly doped and heavily doped CMOS processes. Methods to minimize noise coupling in both the chip design and board design phases are presented along with techniques for accurate circuit simulation of noise coupling....
This thesis examines substrate noise coupling for NMOS transistors in heavily doped substrates. The study begins with the analysis of an NMOS transistor switching noise in a digital inverter at the device level. A resistive substrate network for the NMOS transistor is proposed and verified. Coupling between N+- P+ contacts...
This thesis presents distinctly different methods of accurately predicting phase noise and absolute jitter in ring oscillators. The phase noise prediction methods are the commercially available SpectreRF and isf_tool, a simulator developed in this work from the Hajimiri and Lee theory of phase noise. Absolute jitter due to deterministic supply...
Strategies for simulation and measurement of substrate noise have been analyzed using various digital and analog circuits fabricated in the TSMC 0.35um heavily doped CMOS process. The measurements validate a substrate noise coupling macromodel that has been used to obtain the simulation results. The simulations and measurements also substantiate the...
A new enhanced swing class-D VCO which operates from a supply voltage as low as 300 mV is presented. The architectural advantages are described along with an analysis for the oscillation frequency. Prototype differential and quadrature variants of the proposed VCO have been implemented in a 65 nm RF CMOS...
Attracting, educating and retaining new engineering students is a challenge. The creative aspirations and "can do" attitude spawned by the space race, Heathkits, and homemade crystal radios have been replaced with the passive satisfaction of video games, cell phones and throwaway electronic appliances. At Oregon State University we have made...
IC designers are continuously facing the challenges from reduced CMOS feature sizes and supply voltages. ADCs that deliver satisfactory resolutions/speeds while utilizing the state-of-the-art technologies to save power are in high demand. The analog circuits are more and more assisted by various digital calibration techniques to get boosted performances. This...
The focus of this work is on the steady-state analysis of RE circuits using a coupled device and circuit simulator. Efficient coupling algorithms for both the time-domain shooting method and the frequency-domain harmonic balance method have been developed. A modified Newton shooting method considerably improves the efficiency and reliability of...
A MOS biquadratic (biquad) filter employing the switched-current technique is
reported. The circuit uses current-mode processing which can offer wide
bandwidth, low voltage operation, and can be implemented with standard CMOS
technology. Examples of lowpass, highpass, and bandpass filters are given
which illustrate the synthesis procedures and the versatility of...
Retention of engineering students is a problem for many universities, especially during the first year. The problem of introducing students to engineering while increasing retention rates has recently been addressed by many different universities. Implementing novel lab structures, adjusting the lecture to incorporate more effective teaching techniques, and using orientation...
Digitally-programmable filters have been an ongoing research topic for a number of years. The first such filters were FIR transversal filters using Charge-Coupled Devices (CCD's) and IIR recursive filters using switched-capacitor (SC) techniques. Although both techniques achieve excellent results, they require non-standard and/or additional IC fabrication steps. Low substrate doping...
The design considerations for fast-settling operational
amplifiers (opamps) differ significantly between sampled-data switchedcapacitor
(SC) and conventional continuous-time applications. In SC
circuits, the shape of the output voltage waveform of an opamp is of no
consequence provided that the output settles to within a specified
tolerance of its steady-state value prior...
In this dissertation, two important current mode circuit design subjects have
been explored. In the first part, the switched-current circuit technique has been
investigated. The fundamental performance and limitations of this technique are
explored. One of the major limitations, the signal distortion caused by clock
feedthrough has been substantially reduced...
In this paper, an analysis of the clock-feedthrough effects in
switched-current (SI)' circuits will be presented. The clock-feedthrough
effects caused by the non-ideal characteristic of MOS
switches when they are turned off limit the accuracy of the analog
track-and-hold (T/H) circuits. A model to analyze and characterize this
effect is...
New amplifier architectures are presented using non-traditional methods of biasing. Time-based dynamic biasing and signal-based dynamic biasing are discussed in the context of new architectures. This includes a new form of ring amplification with a dynamic deadzone, allowing for a structure whose coarse path does not consume static power.
Split and normal gate A1GaAs /GaAs MODFETs were fabricated along with
the ohmic test structures and the Hall bar geometries. The DC characteristics of
normal gate transistors were evaluated at room temperature and at 77K and the
threshold voltages were extracted from the measurements and compared to the
theoretical results....
DiskGrapher is a graphical visualization tool designed to help users better manage the
space on their hard drives. The main goal of DiskGrapher is to provide a different
visualization technique to display information, with the goal of providing a more intuitive
understanding of the directory structure of the disk than...
Rhodococcus fascians is a Gram-positive, pleiomorphic actinomycete that causes leafy gall formation in a wide range of plant hosts. This particular phytopathogen has been a focus of research at the Oregon State University Plant Clinic, a diagnostic laboratory. Phylogeny of R. fascians isolates obtained from Plant Clinic submissions was determined...
This dissertation presents a low-power high-resolution delta-sigma ADC. Two new architectural design techniques are proposed to reduce the power dissipation of the ADC. Compared to the conventional active adder, the direct charge transfer (DCT) adder greatly saves power by keeping the feedback factor of the active adder unity. However, the...
Recently, switched-current circuits have received great
attention because they offer potentially better performance in terms
of speed, low voltage power supplies, and accuracy in mixed-mode
analog-digital signal processing. In this thesis, the distortion
characteristics, DC offset and AC gain errors induced by the threshold
voltage, channel width, channel length, and...
With increasing interest in current-mode analogue processing due to its high
performance properties such as speed, bandwidth and accuracy compared to voltage-mode
processing, new current-mode alternatives to various conventional circuit designs are
appearing. In this report, a novel circuit design to construct a fully-differential current-mode
operational amplifier ( OP-AMP )...
This project examines the results of current-voltage conduction mechanism analysis techniques simulated under assumed conduction conditions. Thermionic emission and Fowler-Nordheim tunneling conditions are simulated and analyzed. The resulting plots show how devices behave under different condition mechanisms. The effects of different conduction mechanisms on the results of various analysis techniques...
The world market for sensors is several hundred million dollars growing at an annual rate of 20 percent with accelerometers comprising 19 percent of the market. With an increasing market, a wide range of applications with varying degrees of resolution are in demand. Therefore, there is sufficient motivation for developing...
This paper studies the current counternarcotics methods and the electronics technology used by the United States and Colombian governments to combat narcoterrorism in the Andean region. The efficiency and efficacy of these methods with the use of electronics technology are analyzed to determine if they are
successful. The current counternarcotics...
This thesis presents new, compact configurations for RF/microwave bandstop and lowpass filters for embedded passive applications. A simple design methodology is presented for designing the folded-transmission line filters on a microstrip platform. Unlike the conventional stub-loaded filter designs, the proposed folded-line filters will have practical dimensions for a wide range...
There is a large and growing market for portable consumer audio products
with very small size. As the size of these products is reduced, the area occupied
by batteries becomes significant and hence limits the number of batteries to one.
In order to build such small products, high levels of...