Higher Order Noise-Shaping Filters for High-Performance Micromachined Accelerometers
ABSTRACT Micromachined inertial sensors that have been incorporated in sigma-delta force-feedback loops have been proven to improve linearity, dynamic range, and bandwidth, and also provide a direct digital output. Previous work mainly focused on using the sensing element only to form a second-order single-loop sigma-delta modulator (SigmaDeltaM); however, the advantages of higher order single-loop electromechanical SigmaDeltaM have not been fully explored. High-performance inertial sensors require higher signal-to-quantization noise ratio (SQNR). This paper presents topologies for higher order single-loop electromechanical SigmaDeltaM with optimal stable coefficients that lead to a better SQNR. The topologies have good immunity to fabrication tolerances, which was verified by Monte Carlo analysis. The topologies are applicable not only to accelerometers but also to other inertial sensors such as gyroscopes.
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ABSTRACT: This paper presents a closed-loop interface circuit for high quality factor (Q) capacitive micro-accelerometers. High-Q sensing element is desirable for high resolution, but makes the loop control a great challenge. Considering this, closed-loop implementation utilizing analog force feedback is preferred rather than electromechanical ΔΣ, which is very popular in recent years. To overcome the non-linearity problem of traditional analogue force feedback scheme, pulse width modulation (PWM) force feedback is developed. The chip measures 2.5×2.5mm2 in a commercial 0.35μm CMOS process. Using a high-Q capacitive micro-accelerometer, the interface circuit attains an input range of ±1.25g, a white noise equivalent acceleration (NEA) of 17μg/√Hz, a less than 0.1% non-linearity from a single 5V supply, and a good degree of robustness.Microelectronics and Electronics (PrimeAsia), 2011 Asia Pacific Conference on Postgraduate Research in; 01/2011
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ABSTRACT: The major challenge of multi-domain application design is that the different domains often closely interact with each other. So a separate design of each component and afterwards combining them to the application often does not result in the expected application function. Application modeling at transistor level is not feasible in terms of simulation duration and data handling. This work proposes a new approach for Application Hardware Modeling which addressing the risks of performance degradation caused by interferences between the components through modeling component performances and through virtually validating the application performance in the system environment. The simulations consider all the relevant components that could have an impact on the performance at application level to predict them. The fundamental of Application Hardware Modeling for right-on-first-pass applications is to select the relevant models for a given component, along with the creation and validation of models through equivalence checking, which are presented in this article.Semiconductor Conference Dresden-Grenoble (ISCDG), 2012 International; 01/2012
Conference Paper: Innovative control systems for MEMS inertial sensors[Show abstract] [Hide abstract]
ABSTRACT: In this paper a variety of innovative control systems for MEMS inertial sensors are discussed. These control interfaces have considerable potential to improve important characteristics of MEMS inertial sensors, such as linearity, bandwidth, dynamic range and susceptibility again fabrication tolerances. All control systems are based on the incorporation of the micromachined sensing element in a sigma-delta modulator loop forming an electro-mechanical sigma-delta modulator (EMSDM). A very effective design methodology for such EMSDM based on a Genetic Algorithm is introduced. Subsequently, a high order, single loop EMSDM and a Multi Stage Noise Shaping (MASH) EMSDM are discussed for an accelerometer. For MEMS gyroscopes, results from a bandpass EMSDM and a novel quadrature EMSDM are presented.Frequency Control Symposium (FCS), 2012 IEEE International; 01/2012