High mass resolution of sensors based on film bulk acoustic resonators （FBARs） is required for the detection of small molecules with the low concentration. An active control scheme is presented to improve the mass resolution of the FBAR sen- sors by adding a feedback voltage onto the driving voltage between two electrodes of the FBAR sensors, The feedback voltage is obtained by giving a constant gain and a constant phase shift to the current on the electrodes of the FBAR sensors. The acoustic energy produced by the feedback voltage partly compensates the acoustic energy loss due to the material damping and the acoustic scattering, and thus improves the quality factor and the mass resolution of the FBAR sensors. An explicit expression relating to the impedance and the frequency for an FBAR sensor with the active control is derived based on the continuum theory by neglecting the influence of the electrodes. Numerical simulations show that the impedance of the FBAR sensor strongly depends on the gain and the phase shift of the feedback voltage, and the mass resolution of the FBAR sensor can greatly be improved when the appropriate gain and the phase shift of the feedback voltage are used. The active control scheme also provides an effective solution to improve the resolution of the quartz crystal microbalance （QCM）.
热敏电阻型红外探测器是红外地球敏感器的核心元件,其质量决定整个卫星姿态测量精度。热敏电阻型红外探测器元件制造过程工艺复杂,技术难点大。由于该类器件的失效主要表现为噪声失效,因此,需要研究新的噪声测试方法来剔除失效器件。针对以锰钴镍氧化物作为灵敏元的红外探测器的特点,在分析其噪声模型的基础上,研究了不同偏压下噪声测试方法,并提出了相应测试系统的设计方案。通过测试验证,该系统本底噪声小于100 n V/Hz^(1/2),测试精度也满足要求,可以利用该测试方法进一步剔除存在疑点的探测器,提高红外探测器筛选有效性。该系统将为热敏电阻型红外探测器不同偏压下噪声筛选提供实验平台,并为进一步分析和研究不同偏压下噪声变化机理的研究奠定了基础。
