函數(shù)信號發(fā)生器設(shè)計外文資料及翻譯-免費閱讀
【正文】 這樣就改變了和的輸入，使的輸出開始線性上升，直至升到某一正值為止，該值使間的接點電壓達到0，便引起了另一次翻轉(zhuǎn)。的方波輸出于正負飽和電平間交替交換。這種非線性的出現(xiàn)，就限制了震蕩的幅度，這是所有實際振蕩器工作的基本特征，正如以下討論所表明的那樣：條件并不是給出的可取值范圍，而是給出一個單一的精確值。若干實際的考慮 參考圖12可以看出，如果在振蕩頻率處正好為1，那么將反饋信號接到輸入端，再除去外部信號源將不會造成任何影響。在這種偶然情況下，有可能在幾個頻率處同時振蕩，或在所允許的幾個頻率中某一頻率處出現(xiàn)振蕩。條件=等價于，即環(huán)路增益必須等于1。函數(shù)信號發(fā)生器設(shè)計外文資料及翻譯英文資料原文WAVEFORM GENERATORS Basic Priciple of Sinusoidal Oscillators Many different circuit configurations deliver an essentially sinusoidal output waveform even without inputsignal excitation. The basic principles governing all these oscillators are investigated. In addition to determining the conditions required for oscillation to take place, the frequency and amplitude stability are also studied. show an amplifier, a feedback network, and an input mixing circuit not yet connected to form a closed loop. The amplifier provides an output signal as a consequence of the signal applied directly to the amplifier input terminal. The output of the feedback network is and the output lf the mixing circuit (which is now simply an inverter) is Form the loop gain is Loop gain= An amplifier with transfer gain A and feedback network F not yet connected to form a closed loop.Suppose it should happen that matters are adjusted in such a way that the signalis identically equal to the externally applied input signal. Since the amplifier has no means of distinguishing the source of the input signal applied to it, it would appear that, if the external source were removed and if terminal 2 were connected to terminal 1, the amplifier would continue to provide the same output signal as before. Note, of course, that the statement =means that the instantaneous values of andare exactly equal at all times. The condition=is equivalent to, or the loop gain must equal unity. The Barkhausen Criterion We assume in this discussion of oscillators that the entire circuit operates linearly and that the amplifier or feedback network or both contain reactive elements. Under such circumstances, the only periodic waveform which will preserve, its form is the sinuso
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