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Neelain University Faculty of Engineering Third Class

Neelain University Faculty of Engineering Third Class. Electronic Circuits II Lecture5 Lecturer: Nasreen Ahmed Mekki www. 2014. Operational Amplifier Types. 3. Summing Amplifier

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Neelain University Faculty of Engineering Third Class

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  1. Neelain UniversityFaculty of EngineeringThird Class Electronic Circuits II Lecture5 Lecturer: Nasreen Ahmed Mekki www. 2014

  2. Operational Amplifier Types 3. Summing Amplifier • The circuit in Fig. 14.18a shows a three-input summing amplifier circuit, which provides a means of algebraically summing (adding) three voltages, each multiplied by a constant-gain factor. • Using the equivalent representation shown in Fig. 14.18b, the output voltage can be expressed in terms of the inputs

  3. Integrator • If the feedback component used is a capacitor, as shown in Fig. 14.19a, the resulting connection is called an integrator. • The virtual-ground equivalent circuit (Fig. 14.19b) shows that an expression for the voltage between input and output can be derived in terms of the current I, from input to output. Recall that virtual ground means that we can consider the voltage at the junction of R and XC to be ground but that no current goes into ground at that point. • The capacitive impedance can be expressed as

  4. The integration operation is one of summation, summing the area under a waveform or curve over a period of time. • If a fixed voltage is applied as input to an integrator circuit, Eq. (14.13) shows that the output voltage grows over a period of time, providing a ramp voltage. • The output voltage ramp (for a fixed input voltage) is opposite in polarity to the input voltage and is multiplied by the factor 1/RC.

  5. Example Consider an input voltage, V1=1 V, to the integrator circuit of Fig. 14.20a. Find the output voltage. then change the value of R to 100k.Ω and find the output voltage.

  6. A differentiator circuit is shown in Fig. 14.22. • It’s not as useful as the circuit forms covered above, • the differentiator does provide a useful operation, • the resulting relation for the circuit being • The scale factor is -RC.

  7. CONSTANT-GAIN MULTIPLIER The constant-gain multiplier of op-amp circuits is: • inverting amplifier • Noninverting amplifier

  8. Multiple-Stage Gains • When a number of stages are connected in series, the overall gain is the product of the individual stage gains. • Figure 15.5 shows a connection of three stages. • The first stage is connected to provide noninverting. • The next two stages provide an inverting • The overall circuit gain is then noninverting and calculated by

  9. VOLTAGE SUMMING • Figure 15.8 shows the connection with the output being the sum of the three inputs, • each input multiplied by a different gain. • The output voltage is

  10. Referance • “ELECTRONIC DEVICES AND CIRCUIT THEORY”, By ROBERT BOYLESTAD and LOUIS NASHELSKY

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