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The MOSFET is a key device in high-fequency applications,such as swithing sup-plies,because of its high input DC impedance and the majority carriers participating in thecurrent conduction.Unfortunately,owing to the limitation of the c... 相似文献
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A new power MOSFET Structure with a pn junction--Bipolar Junction MOSFET (BJMOSFET) has been proposed. The device has the advantages of both BJT and FET. The numerical model of the I-V characteristics of BJMOSFET has been obtained on the basis of both numerical and analytical methods. With the software package of Mathematic, we firstly calculate the gain factor, and then simulate the voltage tranmission, voltage output and voltage transfer's characteristic graphs of the BJMOSFET. The simulation result indicates that BJMOSFET has the current density, which is about 25% larger than the power MOSFET, under the same operating conditions and with the same structure parameters, except that the threshold voltage increase a little. 相似文献
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文中介绍了一种与气相色谱仪联用的声表面波气体传感器.传感器由声表面波谐振器作反馈单元的振荡器和半导体制冷器组成.谐振器采用ST-X石英压电基片上双端对谐振式结构,Q值高(1 896)、插入损耗低(4.7 dB).采用在最低损耗点进行相位匹配以改善振荡器短期频率稳定度的方法,其短期频率稳定度达到了11 Hz/s(10-8量级).与气相色谱联用的气体检测试验给出对苯蒸气的检测下限约为150 ppb. 相似文献
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声表面波气体传感器包括采用敏感膜和结合气相色谱两种方式.比较而言,采用敏感膜的声表面波气体传感器体积小、功耗低,但可检测的气体种类少、灵敏度低、存在交叉干扰问题;声表面波与气相色谱联用的气体分析仪灵敏度高、可检测气体种类多、很好地解决交叉干扰问题,特别适合于复杂大气背景条件下的气体成分分析.文中介绍了两类声表面波气体传感器的发展概况. 相似文献
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声表面波气体传感器有采用选择性敏感膜进行气体吸附和气体直接冷凝在声表面波器件表面(与气相色谱系统结合)进行检测两种方式.文中首先从分层介质理论出发,分别对涂敷敏感膜和直接冷凝这两种方式下声表面波器件表面质量负载改变引起的频率变化进行理论分析,比较了两种方式在吸附同样气体条件下的灵敏度;然后计算了在500 MHz工作频率、考虑冷凝液膜轻度粘滞性时,直接冷凝方式的气体检测下限为ppb量级;最后将计算结果与实验结果进行比较并得到验证. 相似文献