Efficient analysis of mixed-signal ASICs for smart sensors
ABSTRACT Smart sensor systems usually contain highly integrated mixed-signal ASICs (application specific integrated circuits). The design of such a circuit typically falls into two distinct tasks: the development of a customized analog part and the design of an often custom-specific digital processor core. While the latter is likely to yield first time right silicon, the former usually requires more design iterations. To speed up the design process, independent optimization of both parts is desirable, but hardly possible in conventional designs. This paper proposes several measures to improve the prototyping and evaluation phase of a class of mixed-signal ASICs typical for smart sensors. Specifically, we suggest using a JTAG-like interface to disentangle analog and digital part and enable external data processing by means of an FPGA (field programmable gate arrays). Furthermore, we propose to replace the RAM/ROM blocks of a user-specific controller with a dual-ported RAM to achieve full programmability while at the same time preserving the overall architecture. Both approaches have successfully been used for the design of a smart sensor system for automotive applications.
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ABSTRACT: This paper presents a contactless capacitive angular speed sensor for automotive applications. The sensor is based on a passive rotating electrode plated between two mechanically static and electrically active electrodes. Differing characteristics of the charge transfer at various sensor positions is utilized as an input for the determination of the rotational speed. The mathematical model of the sensor further enables the optimization of the sensor characteristics for specific applications. Experimental results from a prototype designed for the speed measurement of a steering wheel show a relative speed error of ±4% at a resolution better than 1°/sIEEE Transactions on Instrumentation and Measurement 03/1998; · 1.71 Impact Factor
Conference Paper: Design of an integrated angular sensor system[Show abstract] [Hide abstract]
ABSTRACT: Sensor systems based on capacitive or inductive measurement principles usually require sophisticated analog and digital signal processing. Particularly in automotive applications, a high degree of integration with as few external components as possible is desirable. We describe the design of an integrated angular speed sensor system based on a carrier frequency approach. To optimize the performance, we combined a synchronous demodulation strategy with an external resonance filter serving as clock reference and noise protection. The filter was extended by an additional low-pass easing implementation of the demodulator and compensating for internal signal delays. For system simulation, a simple analytical model based on Fourier synthesis was found to be superior to a conventional SPICE simulationInstrumentation and Measurement Technology Conference, 2001. IMTC 2001. Proceedings of the 18th IEEE; 06/2001
Conference Paper: A robust capacitive angular position sensor[Show abstract] [Hide abstract]
ABSTRACT: A noncontacting robust capacitive angular position sensor currently under development for industrial and automotive application is presented. The main advantages of this low-cost system are its simplicity, high accuracy (±0,2°) and resolution (±0,04°) over the range of up to 360°, excessive temperature operating capability, insensitivity to dirt, moisture and dew on the sensor electrodes and fast measurement speed. The paper describes the working principle, derives the required relationships for computing the rotor position and discusses the sensor's properties in relation to those of established encoder principles. The sensitivity of the sensor to mechanical errors like radial and axial axis offset, tilted axis, and tilted electrodes is explained. Finally the sensor electronics and its realization is discussed and data obtained from prototype sensors is presentedInstrumentation and Measurement Technology Conference, 1996. IMTC-96. Conference Proceedings. 'Quality Measurements: The Indispensable Bridge between Theory and Reality'., IEEE; 02/1996