61 research outputs found
Methods and Devices for Modifying Active Paths in a K-Delta-1-Sigma Modulator
The invention relates to an improved K-Delta-1-Sigma Modulators (KG1Ss) that achieve multi GHz sampling rates with 90 nm and 45 nm CMOS processes, and that provide the capability to balance performance with power in many applications. The improved KD1Ss activate all paths when high performance is needed (e.g. high bandwidth), and reduce the effective bandwidth by shutting down multiple paths when low performance is required. The improved KD1Ss can adjust the baseband filtering for lower bandwidth, and can provide large savings in power consumption while maintaining the communication link, which is a great advantage in space communications. The improved KD1Ss herein provides a receiver that adjusts to accommodate a higher rate when a packet is received at a low bandwidth, and at a initial lower rate, power is saved by turning off paths in the KD1S Analog to Digital Converter, and where when a higher rate is required, multiple paths are enabled in the KD1S to accommodate the higher band widths
Undersampling bandpass modulator architectures
Continuous-time delta sigma modulators -- Undersampling Delta-sigma modulators for radio receivers -- A novel continuous-time delta sigma modulator -- New delta modulator based on undersampling
Integrated interface electronics for capacitive MEMS inertial sensors
This thesis is composed of 13 publications and an overview of the research topic, which also summarizes the work. The research presented in this thesis concentrates on integrated circuits for the realization of interface electronics for capacitive MEMS (micro-electro-mechanical system) inertial sensors, i.e. accelerometers and gyroscopes. The research focuses on circuit techniques for capacitive detection and actuation and on high-voltage and clock generation within the sensor interface.
Characteristics of capacitive accelerometers and gyroscopes and the electronic circuits for accessing the capacitive information in open- and closed-loop configurations are introduced in the thesis. One part of the experimental work, an accelerometer, is realized as a continuous-time closed-loop sensor, and is capable of achieving sub-micro-g resolution. The interface electronics is implemented in a 0.7-µm high-voltage technology. It consists of a force feedback loop, clock generation circuits, and a digitizer. Another part of the experimental work, an analog 2-axis gyroscope, is optimized not only for noise, but predominantly for low power consumption and a small chip area. The implementation includes a pseudo-continuous-time sense readout, analog continuous-time drive loop, phase-locked loop (PLL) for clock generation, and high-voltage circuits for electrostatic excitation and high-voltage detection. The interface is implemented in a 0.35-µm high-voltage technology within an active area of 2.5 mm². The gyroscope achieves a spot noise of 0.015 °/s/√H̅z̅ for the x-axis and 0.041 °/s/√H̅z̅ for the y-axis.
Coherent demodulation and discrete-time signal processing are often an important part of the sensors and also typical examples that require clock signals. Thus, clock generation within the sensor interfaces is also reviewed. The related experimental work includes two integrated charge pump PLLs, which are optimized for compact realization but also considered with regard to their noise performance. Finally, this thesis discusses fully integrated high-voltage generation, which allows a higher electrostatic force and signal current in capacitive sensors. Open- and closed-loop Dickson charge pumps and high-voltage amplifiers have been realized fully on-chip, with the focus being on optimizing the chip area and on generating precise spurious free high-voltage signals up to 27 V
Digital pulse processing
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 71-74).This thesis develops an exact approach for processing pulse signals from an integrate-and-fire system directly in the time-domain. Processing is deterministic and built from simple asynchronous finite-state machines that can perform general piecewise-linear operations. The pulses can then be converted back into an analog or fixed-point digital representation through a filter-based reconstruction. Integrate-and-fire is shown to be equivalent to the first-order sigma-delta modulation used in oversampled noise-shaping converters. The encoder circuits are well known and have simple construction using both current and next-generation technologies. Processing in the pulse-domain provides many benefits including: lower area and power consumption, error tolerance, signal serialization and simple conversion for mixed-signal applications. To study these systems, discrete-event simulation software and an FPGA hardware platform are developed. Many applications of pulse-processing are explored including filtering and signal processing, solving differential equations, optimization, the minsum / Viterbi algorithm, and the decoding of low-density parity-check codes (LDPC). These applications often match the performance of ideal continuous-time analog systems but only require simple digital hardware. Keywords: time-encoding, spike processing, neuromorphic engineering, bit-stream, delta-sigma, sigma-delta converters, binary-valued continuous-time, relaxation-oscillators.by Martin McCormick.S.M
Advances in Solid State Circuit Technologies
This book brings together contributions from experts in the fields to describe the current status of important topics in solid-state circuit technologies. It consists of 20 chapters which are grouped under the following categories: general information, circuits and devices, materials, and characterization techniques. These chapters have been written by renowned experts in the respective fields making this book valuable to the integrated circuits and materials science communities. It is intended for a diverse readership including electrical engineers and material scientists in the industry and academic institutions. Readers will be able to familiarize themselves with the latest technologies in the various fields
Sigma-Delta control of charge trapping in heterogeneous devices
Dielectric charging represents a major reliability issue in a variety of semiconductor devices. The accumulation of charge in dielectric layers of a device often alters its performance, affecting its circuital features and even reducing its effective lifetime. Although several contributions have been made in order to mitigate the undesired effects of charge trapping on circuit performance, dielectric charge trapping still remains an open reliability issue in several applications.
The research work underlying this Thesis mainly focuses on the design, analysis and experimental validation of control strategies to compensate dielectric charging in heterogeneous devices. These control methods are based on the application of specifically designed voltage waveforms that produce complementary effects on the charge dynamics. Using sigma-delta loops, these controls allow to set and maintain, within some limits, the net trapped charge in the dielectric to desired levels that can be changed with time. This allows mitigating long-term reliability issues such as capacitance-voltage (C-V) shifts in MOS and MIM capacitors. Additionally, the bit streams generated by the control loops provide real-time information on the evolution of the trapped charge.
The proposed controls also allow compensating the effects of the charge trapping due to external disturbances such as radiation. This has been demonstrated experimentally with MOS capacitors subjected to various types of ionizing radiation (X-rays and gamma rays) while a charge control is being applied. This approach opens up the possibility of establishing techniques for active compensation of radiation-induced charge in MOS structures as well as a new strategy for radiation sensing.
A modeling strategy to characterize the dynamics of the dielectric charge in MOS capacitors is also presented. The diffusive nature of the charge trapping phenomena allows their behavioral characterization using Diffusive Representation tools. The experiments carried out demonstrate a very good matching between the predictions of the model and the experimental results obtained. The time variations in the charge dynamics due to changes in the volatges applied and/or due to external disturbances have been also investigated and modeled.
Moreover, the charge dynamics of MOS capacitors under sigma-delta control is analyzed using the tools of Sliding Mode Controllers for an infinite sampling frequency approximation. A phenomenological analytical model is obtained which allows to predict and analyze the sequence of control signals. This model has been successfully validated with experimental data.
Finally, the above control strategies are extended to other devices such as eMIM capacitors and perovskite solar cells. Preliminary results including open loop and closed loop control experiments are presented. These results demonstrate that the application of the controls allows to set and stabilize both the C-V characteristic of an eMIM capacitor and the current-voltage characteristic (J-V) of a perovskite solar cell.La carga atrapada en dieléctricos suele implicar un problema importante de fiabilidad en muchos dispositivos semiconductores. La acumulación de dicha carga, normalmente provocada por las tensiones aplicadas durante el uso del dispositivo, suele alterar el rendimiento de éste con el tiempo, afectar sus prestaciones a nivel de circuital e, incluso, reducir su vida útil. Aunque durante años se han realizado muchos trabajos para mitigar sus efectos no deseados, sobre todo a nivel circuital, la carga atrapada en dieléctricos sigue siendo un problema abierto que frena la aplicabilidad práctica de algunos dispositivos. El trabajo de investigación realizado en esta Tesis se centra principalmente en el diseño, análisis y validación experimental de estrategias de control para compensar la carga atrapada en dieléctricos de diversos tipos de dispositivos, incluyendo condensadores MOS, condensadores MIM fabricados con nanotecnología y dispositivos basados en perovskitas. Los controles propuestos se basan en utilizar formas de onda de tensión, específicamente diseñadas, que producen efectos complementarios en la dinámica de la carga. Mediante el uso de lazos sigma-delta, estos controles permiten establecer y mantener, dentro de unos límites, la carga neta atrapada en el dieléctrico a valores prefijados, que pueden cambiarse con el tiempo. Esto permite mitigar problemas de fiabilidad a largo plazo como por ejemplo las derivas de la curva capacidad-tensión (C-V) en condensadores MOS y MIM. Adicionalmente, las tramas de bits generadas por los lazos de control proporcionan información en tiempo real sobre la evolución de la carga. Los controles propuestos permiten también compensar los efectos de la carga atrapada en dieléctricos debida a perturbaciones externas como la radiación. Esto se ha demostrado experimentalmente con condesadores MOS sometidos a diversos tipos de radiación ionizante (rayos X y gamma) mientras se les aplicaba un control de carga. Este resultado abre la posibilidad tanto de establecer técnicas de compensación activa de carga inducida por radiación en estructuras MOS, como una nueva estrategia de sensado de radiación. Se presenta también una estrategia de modelado para caracterizar la dinámica de la carga dieléctrica en condensadores MOS. La naturaleza difusiva de los fenómenos de captura y eliminación de carga en dieléctricos permite caracterizar dichos fenómenos empleando herramientas de Representación Difusiva. Los experimentos realizados demuestran una muy buena correspondencia entre las predicciones del modelo y los resultados experimentales obtenidos. Se muestra también como las variaciones temporales de los modelos son debidas a cambios en las formas de onda de actuación del dispositivo y/o a perturbaciones externas. Además, la dinámica de carga en condensadores MOS bajo control sigma-delta se analiza utilizando herramientas de control en modo deslizante (SMC), considerando la aproximación de frecuencia de muestreo infinita. Con ello se obtiene un modelo analítico simplificado que permite predecir y analizar con éxito la secuencia de señales de control. Este modelo se ha validado satisfactoriamente con datos experimentales. Finalmente, las estrategias de control anteriores se han extendido a otros dispositivos susceptibles de sufrir efectos de carga atrapada que pueden afectar su fiabilidad. Así, se han llevado a cabo experimentos preliminares cuyos resultados demuestran que la aplicación de controles de carga permite controlar y estabilizar la característica C-V de un condensador eMIM y la característica corriente-tensión (J-V) de una célula solar basada en perovskitas.Postprint (published version
Sigma-Delta control of charge trapping in heterogeneous devices
Dielectric charging represents a major reliability issue in a variety of semiconductor devices. The accumulation of charge in dielectric layers of a device often alters its performance, affecting its circuital features and even reducing its effective lifetime. Although several contributions have been made in order to mitigate the undesired effects of charge trapping on circuit performance, dielectric charge trapping still remains an open reliability issue in several applications.
The research work underlying this Thesis mainly focuses on the design, analysis and experimental validation of control strategies to compensate dielectric charging in heterogeneous devices. These control methods are based on the application of specifically designed voltage waveforms that produce complementary effects on the charge dynamics. Using sigma-delta loops, these controls allow to set and maintain, within some limits, the net trapped charge in the dielectric to desired levels that can be changed with time. This allows mitigating long-term reliability issues such as capacitance-voltage (C-V) shifts in MOS and MIM capacitors. Additionally, the bit streams generated by the control loops provide real-time information on the evolution of the trapped charge.
The proposed controls also allow compensating the effects of the charge trapping due to external disturbances such as radiation. This has been demonstrated experimentally with MOS capacitors subjected to various types of ionizing radiation (X-rays and gamma rays) while a charge control is being applied. This approach opens up the possibility of establishing techniques for active compensation of radiation-induced charge in MOS structures as well as a new strategy for radiation sensing.
A modeling strategy to characterize the dynamics of the dielectric charge in MOS capacitors is also presented. The diffusive nature of the charge trapping phenomena allows their behavioral characterization using Diffusive Representation tools. The experiments carried out demonstrate a very good matching between the predictions of the model and the experimental results obtained. The time variations in the charge dynamics due to changes in the volatges applied and/or due to external disturbances have been also investigated and modeled.
Moreover, the charge dynamics of MOS capacitors under sigma-delta control is analyzed using the tools of Sliding Mode Controllers for an infinite sampling frequency approximation. A phenomenological analytical model is obtained which allows to predict and analyze the sequence of control signals. This model has been successfully validated with experimental data.
Finally, the above control strategies are extended to other devices such as eMIM capacitors and perovskite solar cells. Preliminary results including open loop and closed loop control experiments are presented. These results demonstrate that the application of the controls allows to set and stabilize both the C-V characteristic of an eMIM capacitor and the current-voltage characteristic (J-V) of a perovskite solar cell.La carga atrapada en dieléctricos suele implicar un problema importante de fiabilidad en muchos dispositivos semiconductores. La acumulación de dicha carga, normalmente provocada por las tensiones aplicadas durante el uso del dispositivo, suele alterar el rendimiento de éste con el tiempo, afectar sus prestaciones a nivel de circuital e, incluso, reducir su vida útil. Aunque durante años se han realizado muchos trabajos para mitigar sus efectos no deseados, sobre todo a nivel circuital, la carga atrapada en dieléctricos sigue siendo un problema abierto que frena la aplicabilidad práctica de algunos dispositivos. El trabajo de investigación realizado en esta Tesis se centra principalmente en el diseño, análisis y validación experimental de estrategias de control para compensar la carga atrapada en dieléctricos de diversos tipos de dispositivos, incluyendo condensadores MOS, condensadores MIM fabricados con nanotecnología y dispositivos basados en perovskitas. Los controles propuestos se basan en utilizar formas de onda de tensión, específicamente diseñadas, que producen efectos complementarios en la dinámica de la carga. Mediante el uso de lazos sigma-delta, estos controles permiten establecer y mantener, dentro de unos límites, la carga neta atrapada en el dieléctrico a valores prefijados, que pueden cambiarse con el tiempo. Esto permite mitigar problemas de fiabilidad a largo plazo como por ejemplo las derivas de la curva capacidad-tensión (C-V) en condensadores MOS y MIM. Adicionalmente, las tramas de bits generadas por los lazos de control proporcionan información en tiempo real sobre la evolución de la carga. Los controles propuestos permiten también compensar los efectos de la carga atrapada en dieléctricos debida a perturbaciones externas como la radiación. Esto se ha demostrado experimentalmente con condesadores MOS sometidos a diversos tipos de radiación ionizante (rayos X y gamma) mientras se les aplicaba un control de carga. Este resultado abre la posibilidad tanto de establecer técnicas de compensación activa de carga inducida por radiación en estructuras MOS, como una nueva estrategia de sensado de radiación. Se presenta también una estrategia de modelado para caracterizar la dinámica de la carga dieléctrica en condensadores MOS. La naturaleza difusiva de los fenómenos de captura y eliminación de carga en dieléctricos permite caracterizar dichos fenómenos empleando herramientas de Representación Difusiva. Los experimentos realizados demuestran una muy buena correspondencia entre las predicciones del modelo y los resultados experimentales obtenidos. Se muestra también como las variaciones temporales de los modelos son debidas a cambios en las formas de onda de actuación del dispositivo y/o a perturbaciones externas. Además, la dinámica de carga en condensadores MOS bajo control sigma-delta se analiza utilizando herramientas de control en modo deslizante (SMC), considerando la aproximación de frecuencia de muestreo infinita. Con ello se obtiene un modelo analítico simplificado que permite predecir y analizar con éxito la secuencia de señales de control. Este modelo se ha validado satisfactoriamente con datos experimentales. Finalmente, las estrategias de control anteriores se han extendido a otros dispositivos susceptibles de sufrir efectos de carga atrapada que pueden afectar su fiabilidad. Así, se han llevado a cabo experimentos preliminares cuyos resultados demuestran que la aplicación de controles de carga permite controlar y estabilizar la característica C-V de un condensador eMIM y la característica corriente-tensión (J-V) de una célula solar basada en perovskitas
Engineering Education and Research Using MATLAB
MATLAB is a software package used primarily in the field of engineering for signal processing, numerical data analysis, modeling, programming, simulation, and computer graphic visualization. In the last few years, it has become widely accepted as an efficient tool, and, therefore, its use has significantly increased in scientific communities and academic institutions. This book consists of 20 chapters presenting research works using MATLAB tools. Chapters include techniques for programming and developing Graphical User Interfaces (GUIs), dynamic systems, electric machines, signal and image processing, power electronics, mixed signal circuits, genetic programming, digital watermarking, control systems, time-series regression modeling, and artificial neural networks
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