This paper describes a technique for estimating total jitter that, along with a loopback-based margining test, can be applied to test high speed serial interfaces. We first present the limitations of the existing estimation method, which is based on the dual-Dirac model. The accuracy of the existing method is extremely sensitive to the choice of the fitting region and the ratio of deterministic jitter to random jitter. Then, we propose a high-order polynomial fitting technique and demonstrate its value for a more efficient and accurate total jitter estimation at a very low Bit-Error-Rate level. The estimation accuracy is also analyzed with respect to different numbers of measurement points for fitting. This analysis shows that only a very small number (i.e., 4) of measurement points is needed for achieving accurate estimation.16th IEEE Asian Test Symposium

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The engines of electric and hybrid vehicles cause vibration and noise with complex frequency spectra. This tendency is observed especially for mid-frequency components. Therefore, there are limitations in achieving vibration attenuation using only structural changes, which is the conventional isolation method. A smart structure-based active engine mounting system is a core technology that can continuously improve the noise, vibration, and harshness performance under various operating conditions by continuously controlling the dynamic characteristics of the mount. It can replace the existing mount technology which supports the engine by realizing both static and dynamic stiffness. This study focuses on vibration reduction for a typical mid-frequency excitation. Based on a source–path–receiver structure, a mathematical model for a 3D plate structure with three active paths is proposed. The amplitude and phase of the actuator were calculated for the reduction of given vibrations on the basis of the model. When controlling with the proposed method, it was necessary to perform a large amount of computation and to newly define the modeling according to the structural change. To solve this inconvenience, the NLMS (normalized least mean squares) algorithm was applied, and the results were compared. It is shown that the application of the NLMS algorithm to perform the overall vibration reduction is more effective than the previous method.

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