NanoGetters for MEMS Hermetic Packaging

A new getter, we call it nanogetter, based on carbon nanotubes (CNTs) coated Ti films has been developed with the purpose of providing a more efficient material, capable of getting active at high vacuum environment (< 10(-3)Torr, molecular state) and low temperature (<400 degrees C). Because of the large surface area of CNTs and its native gas adsorption ability, dense CNTs growth on silicon substrate is considered to be an effective skeleton structure of the nanogetters. All the tests have demonstrated that surface area of nanogetters do have been increased and the pumping speed is enhanced to large amount compared with some traditional getters, such as St175 of SAES in Italy

Averaged Behavior Model of Current-Mode Buck Converters for Transient Power Noise Analysis

Accurate Evaluation and Simulation of Power Noise is Critical in the Development of Modern Electronic Devices. However, the Widely Used Target Impedance Fails to Predict the Low-Frequency Noise Generated in a Device Due to the Existence of the Dc–dc Converter, Whose Output Impedance Can Change under Different Loading Conditions. a Physical Circuit Model is Then Desired to Replicate the Behavior of a Voltage Regulator Module, and the Average Technique is an Efficient Method to Estimate the Noise of a Pulse Width-Modulated (PWM) Converter. with the Emergence of Converters with Adaptive On-Time (AOT) Controllers, More Complex Averaging Methods Are Required, But None of Them Supports Transient Simulation. a General, Efficient, and Accurate Modeling Technique is Presented in This Article, Whose Framework Supports Both Current-Mode PWM and AOT Controllers. in Addition, a Novel Two-Step Parameter Extraction Method is Proposed, Which Can Be Used to Evaluate the Equivalent Values of Internal Feedback Parameters of an Encrypted Simulation Model or from Measurement. the Modeling Method is Validated by Both Simulation and Measurement

Creación y Simulación de Metodologías de Análisis, Clasificación e Integración de Nuevos Requerimientos a Software Propietario

La priorización de nuevos requerimientos a implementar en un software propietario es un punto fundamental para su mantenimiento, la conservación de la calidad, observación de las reglas de negocio y los estándares de la empresa. Aunque existen herramientas de priorización basadas en técnicas probadas y reconocidas, las mismas requieren una calificación previa de cada requerimiento. Si la empresa cuenta con solicitudes provenientes de varios clientes de un mismo producto, aumentan los factores que afectan a la empresa, las herramientas disponibles no contemplan estos aspectos y hacen mucho más compleja la tarea de calificación. Este trabajo de investigación abarca la realización de un relevamiento de los métodos de priorización y selección de nuevos requerimientos utilizados por empresas de la zona de Rosario, y la definición de una metodología para la selección un nuevo requerimiento, que implica el análisis y evaluación de todas las implicaciones sobre el producto de software y la empresa, respetando sus reglas de negocio. La metodología creada conduce a la definición de los procesos para la construcción de una herramienta de calificación y priorización de nuevos requerimientos en software propietario que tiene solicitudes de varios clientes al mismo tiempo, con instrumentos de calificación que consideran todos los aspectos relacionados, proveerá técnicas de priorización actuales y emitirá informes personalizados según diferentes perspectivas de la empresa.Eje: Ingeniería de SoftwareRed de Universidades con Carreras en Informática (RedUNCI

Measurement Methodologies for Acoustic Noise Induced by Multilayer Ceramic Capacitors of Power Distribution Network in Mobile Systems

In this article, acoustic noise of printed circuit board (PCB) introduced by multilayer ceramic capacitors (MLCCs) on power distribution network (PDN) is studied. The correlation of PDN power rail noise, MLCCs and PCB dynamic characteristics, and PCB acoustic noise is demonstrated on a real mobile product through electrical, vibrational, and acoustic measurements. Two measurement methodologies are proposed to identify the problematic MLCCs on the power rail. One method analyzes the board and MLCCs vibration properties with the external electrical signal applied on the power rail on a product board. Other measurement detects the problematic MLCCs based on the coherence value between the power rail signal during product operation and MLCC vibration characteristics. By replacing the identified original MLCCs with low acoustic noise ones, the PCB vibration is clearly reduced. With the MLCCs\u27 influence on PCB vibration studied, a measurement methodology is also proposed to analyze the PCB intrinsic vibration properties. The intrinsic modal response of PCB is applied to predict the MLCC-induced PCB vibration. The obtained modal response can also provide design guidelines for MLCC placement to reduce the level of PCB vibration

Decoupling Capacitor Layout Design Guidelines for Acoustic Noise Consideration in Power Distribution Network

Acoustic noise induced by multilayer ceramic capacitors (MLCCs) in power distribution network (PDN) is a critical issue regarding product user experience. In this work, design guidelines for decoupling capacitor selection, layout geometries are proposed targeting the acoustic noise, through analysis of the acoustic noise generation mechanism in printed circuit board (PCB). A test board is designed to validate the proposed design guidelines. With sound pressure level measurement of the test vehicle, the effectiveness of the proposed design guidelines is confirmed. In general, the decoupling capacitor layout design guidelines for acoustic noise consideration are consistent with the requirements for PDN to achieve high electrical performance

Simulation Investigation on Acoustic Noise Caused by Singing Capacitors on Mobile Devices

Recently, the acoustic noise emanating from mobile devices becomes an important issue for user experience. The vibration of multilayer ceramic capacitors (MLCCs) mounted on printed circuit board (PCB) can transfer to the PCB and lead to acoustic noise. To mitigate singing cap acoustic noise, sometimes it has to trade off EMC/SI/PI performance during system design. So, simulation methodology is critical to predict critical acoustic issue and help design tradeoff. In this paper, a simulation methodology to provide design guideline for MLCC placement and PCB fixation with the aim to decrease board vibration is proposed. A finite element model of the multilayer PCB considering detailed copper/dielectric distribution of each layer is developed. Modal analysis is firstly performed to analyze the vibration characteristics of the bare PCB. Then the harmonic response of the board due to vibration excitation of MLCC is modeled. Based on the modal analysis result, the design guideline for MLCC placement and PCB fixation location can be established. The proposed guideline is validated through PCB harmonic response simulation

Measurement Investigation of MLCC Mounting Variation Impact on Acoustic Noise in Power Distribution Network

The multilayer ceramic capacitors (MLCCs) mounting method impact on the MLCC induced acoustic noise in printed circuit board (PCB) is investigated through measurement. The influence of MLCC soldering stencil height, MLCC orientation and MLCC pair offset distance are evaluated on a series of test boards. The sound pressure level (SPL) is measured to evaluate the PCB acoustic noise performance. In the investigated mounting variation range, the acoustic noise performance does not exhibit noticeable changes

Measurement Investigation on Acoustic Noise Caused by Singing Capacitors on Mobile Devices

Acoustic noise from mobile devices can be annoying for customers. Multilayer ceramic capacitors (MLCCs) soldered on printed circuit board (PCB) are known to be a main source of acoustic noise. The PCB in these devices feature hundreds of MLCCs. In this paper, a measurement methodology to identify the major vibrating MLCCs on board is presented. Laser Doppler vibrometer scanning result is used to find the dominant MLCC source. The correlation between board vibration and acoustic noise is confirmed with microphone probe. As a result of the piezoelectric properties of MLCCs, the root cause of the vibration is analyzed from an electric point of view. The problematic MLCCs are find to share the same power line which renders the same noise peaks as in the vibration and sound pressure measurements. After replacing the vibrating MLCCs with low acoustic noise MLCCs, the board clearly shows decreased level of vibration