In this paper, we present a capacitive, MEMS-based accelerometer comprising an ultra-low noise CMOS integrated readout-IC and a high-precision bulk micro machined sensing element. The resulting accelerometer reaches an acceleration equivalent noise of only 200 ng/√Hz, which makes it suitable for seismic measurement that require noise levels significantly below 1 µg/√Hz. Additionally, a high bandwidth of more than 5 kHz was achieved, which also makes the presented sensor system applicable for high-frequency measurements, e.g. in predictive maintenance applications for rotating machinery. The design of the sensing element and readout IC is presented in detail and measurement results are shown which demonstrate the performance of the sensor system.

Abstract. In this paper we present a readout circuit for capacitive micro-electro-mechanical system (MEMS) sensors such as accelerometers, gyroscopes or pressure sensors. A flexible interface allows connection of a wide range of types of sensing elements. The ASIC (application-specific integrated circuit) was designed with a focus on ultra-low noise operation and high analog measurement performance. Theoretical considerations on system noise are presented which lead to design requirements affecting the reachable overall measurement performance. Special emphasis is put on the design of the fully differential operational amplifiers, as these have the dominant influence on the achievable overall performance. The measured input referred noise is below 50 zF/ √Hz within a bandwidth of 10 Hz to 10 kHz. Four adjustable gain settings allow the adaption to measurement ranges from ±750 fF to ±3 pF. This ensures compatibility with a wide range of sensor applications. The full input signal bandwidth ranges from 0 Hz to more than 50 kHz. A high-precision accelerometer system was built from the described ASIC and a high-sensitivity, low-noise sensor MEMS. The design of the MEMS is outlined and the overall system performance, which yields a combined noise floor of 200 ng/ √ Hz, is demonstrated. Finally, we show an application using the ASIC together with a CMOS integrated capacitive pressure sensor, which yields a measurement signal-to-noise ratio (SNR) of more than 100 dB.

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A novel approach for enabling distributed design of heterogeneous systems and components is introduced in the paper. It integrates concepts of visual knowledge modeling, engineering workflows, collaborative workspaces, design task patterns, and remote tool invocation. These concepts are supported by a collaboration platform -a result of the EU FP6 project MAPPER. The design approach and the supporting collaboration platform have been applied in the USB2 OTG PHY IP core design that required collaboration among two dispersed SMEs.Mixed-signal USB design challenges, distributed design flow, requirements for enhanced EDA support, and selected design tasks enabled by the collaboration platform have been discussed. Finally, advantages and constraints of the design approach have been pointed to.