## Wednesday, February 27, 2013

### Electronic Note

Amplifier

In a comparator go, as discussed previously, we have seen the Op-Amp is use in an open loop condition. When used as an amplifier, it is restricted to contain in linear, almost vertical, part of its transfer characteristics by fresh application of negative feedback.

Concept of virtual laconic circuit circuit:

Operational amplifier has got very broad(prenominal) gain (Ad) and coupled with noble input resistance (Ri) gives rise to an interesting concomitant:
If the Op-Amp has to be operated in its linear region of transfer characteristics, the differential potential must be kept extremely excellent because the relation back V0 = AdVd is valid that in the linear region and only in this region the device can be used as a linear amplifier. If we think of an ideal situation in which gain tends to infinity, Vd tends to zero. That is, the inverting and the non-inverting terminals turn out as though they ar in a state of short circuit. We are quite familiar with the term short circuit and our induce is that when two points in an electrical circuit are short circuited, enormous current can flow between them. barely in the case of an Op-Amp, it is a peculiar kind of short circuit, hitherto not experienced:
Thus maintaining the condition of infinitesimally small differential voltage, if we now couple the property of very high input resistance Ri, we find that the current drawn by the amplifier (Vd / Ri) becomes negligibly small. For example taking the dc supply voltage to be 10 volt, gain of the severalize of 105, and input resistance of the order 100 kilo ohm, we find maximum value of Vd is 0.1 mV, and the current drawn by the terminals works out to be of the order of 0.1 mV/ 100 k( i.e. 1 nA. Hence in the ideal situation of infinite input resistance, the current withal tends to zero. This means that as far as the voltage is pertain the inverting and the non-inverting terminals behave like a short circuit; exactly as far as the current is concerned they behave like an open circuit. This...If you want to get a sufficient essay, order it on our website: Orderessay

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