Category Archive for: Operational Ampiifier Theory

The Total Output Offset Voltage

We have seen that output offset voltage is a function of two distinct input characteristics: input bias currents and input offset voltage. It may be that the polarities of the offsets caused by these two characteristics are such that they tend to cancel each other out. Of course, we cannot depend on that happy circumstance. so it is good…

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OFFSET CURRENTS AND VOLTAGES

Recall from  that one of the chnrnctcristi.cs of an ideal operational amplifier is that It has zero output voltage when both inputs are 0 V (grounded), This chaructoristic is p~rHc~larly importa~t in appllcations .where de or 19 w-frequency signals arc . If the output IS not 0 :when ~he inputs . then the output will not he lit Its…

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User Compensated Amplifiers

As noted earlier, many commercially available amplifiers have internal compensation circuitry to make the frequency response roll off at 6 dB/octave (20 dB/decade) over the entire frequency range from j;. to f, (Figure 13-15). Some amplilkr:-not have such circuitry and must he compensated by connecting external roll-off networks. These networks. typically RC circuits, are selected by the user…

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FREQUENCY RESPONSE

Stability When Ilw wm! “!dhiltly ‘,! used ill “/,1 ncction with. a high-gain amplifier. it usually means the property of behaving like an amplifier (ather than like an os .illau»: An osci lutor is H, device that .pontaneously generates an ac signal because of positive. feedback. We will st udy oscillator theory in Chapter 14, but for…

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Feedback in the Inverting Amplifier

To investigate the effect of open-loop gain A and feedback ratio f3 on the closedloop gain of the inverting amplifier. let us recall equations 13-6 and 13-7 from Section 13-1: Once again we see that the closed-loop gain reduces to the ideal amplifier value. -RlR” when A = 00. Notice that the denominator of (13-28) is the same…

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FEEDBACK THEORY

We have seen that we can control the closcc-loop gai,n v..Ivu, of an operational [amplifier by introducing feedback through external resistor: combinations. We wi h now to examine the feedback mechanism in detail and discover some other important consequences of its use. Feedback theory is widely used to study the behavior of electronic components as wel! a complex systems…

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The Inverting Amplifier

Consider the configuration shown in Figure 13-2, In this very useful application of an operational amplifier, the noninverting input is grounded, VIII is connected through RI to the inverting input. and feedback resistor R, is connected between the output and V;  Let A denote the voltage gain of the amplifier: V” = A (v / V; ), Since u]…

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Operational Ampiifier Theory

Recall that an operational amplifier is a direct-coupled amplifier with two (differential) inputs and a single output. In Chapter 12,we listed I11ne«es.rablc character! tics of an operational amplifier; we wish now to focus on three of those. We will an ideal operational amplifier to be one that has the following attributes: L It has infinite gain. 2. It…

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