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对于解决调节回差同时牵制两个触发阈的问题,本文从运算放大器施密特电路阈值调节的原理出发,提出了两种方法——补偿法和钳位法,并提供了实验验证的结果。又从几种基本曲线的相互关系的分析中阐明了进一步提高性能的关键,从而获得了调节回差时仅仅变动一个阈值,另一个阈值不变化的特有性能。这种改进的电路能将单纤维光电讯号直接转换成计数脉冲,灵敏度可达5毫伏以下。输入阻抗大于10~6欧姆。当回差值增加390倍时,其中一个阈仅变化2.1毫伏,可认为是相当稳定的。这种方法可以推广到其它微弱讯号的检测中,有助于灵活地设计和应用运算放大器施密特电路,精确地设置阈值和回差。
In order to solve the problem of adjusting the hysteresis while keeping the two triggering thresholds down, two methods are proposed based on the principle of the threshold adjustment of the operational amplifier Schmitt circuit, the compensation method and the clamping method, and the experimental verification results are provided. From the analysis of the relationship between several basic curves, the key to further improve the performance is clarified, and the unique performance that only one threshold changes while the other threshold does not change is obtained. This improved circuit converts single fiber optoelectronic signals directly into count pulses with a sensitivity of up to 5 millivolts. Input impedance greater than 10 ~ 6 ohms. When the hysteresis is increased 390 times, one of the thresholds changes only 2.1 millivolts, which is considered quite stable. This approach can be extended to other weak signal detection, help to design and application of op amp Schmitt circuit, accurately set the threshold and backlash.