- Aug 14, 2017 -
Amplifier Knowledge Classic Quiz
1. What is Open-loop voltage gain?
Open-loop voltage gain is the ratio of the voltage variation in the output of the amplifier to that of the input voltage when the input and output of the amplifier is open.
2. What is the common-mode inhibition ratio?
The common-mode inhibition ratio is the ratio of the amplifier to the magnification of the differential voltage signal and the multiple-mode voltage signal, in db.
3. What is input current noise (in)?
Input current noise: is the equivalent current noise of the input parallel application of the noise-free amplifier.
4. What is the difference between the voltage feedback amplifier and the current feedback amplifier?
The two kinds of internal circuits are different, so for a given configuration, there is no need to swap the two types of op-drop. The voltage feedback is controlled by the internal design, with very low input bias, but no internal limit. The differential input voltage is limited only when external feedback is required. Conversely, for a current-feedback amplifier, the differential input voltage is constrained by the internal design, but does not limit its input bias to low, so only when external feedback is needed. Although most universities still do not have the basic knowledge of current feedback amplifiers, the use of current-feedback amplifiers has many advantages, especially in high-speed applications.
5. What is the difference between Open-loop and closed loop?
"Open-loop gain" is actually an "internal" gain with no feedback, usually from 1,000 to 10,000,000 of any value. Look at the "Open loop gain" diagram in the data sheet; "Closed loop gain" is the gain of the entire circuit, with feedback from the user choosing the appropriate feedback resistance value, such as "Gain +10" or "Gain 2".
6. What is the output current?
The output current is the current of the drive load from the output end of the op-put. It is usually a function: input over drive, output voltage and power of correlation, temperature. The characteristics of the source and drain poles vary.
7. I have chosen the rail alignment (rail-to-rail) input/output (input/output) amplifier, but the output is not always a negative track, or is always on track. Did I do something wrong?
The word "orbital alignment (Rail-to-rail)" is misleading. The completely correct should be "almost axle to axle" or "very close axle to axle". Most R amplifiers have an output voltage from 20 to 200mv on any power rail, and almost never have a pair of rails. When more load current is needed, the output is farther away from the power supply voltage rail. Most amplifiers provide a maximum output voltage swing through a 100k or greater load. In the product data sheet and the characteristic curve, the specified output voltage fluctuation is expected. In addition, when creating a design through the amplifier, the user can require the performance of the "rail alignment" output amplifier. The op-and-drop listed in the selection table will meet the requirements of the design output swing, and the frequency of the "rail to rail" output device in the selected reference table is the most frequent.
8. What is the phase margin?
Phase margin (Phasemargin): In Open-loop circuits, the phase shift between the output of the same frequency and the inverse phase input.