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Unformatted text preview: L 13 QUESTIONS AND PROBLEMS 1. Solve Equation 9—27 for constant Vm. What type of
.3. a1 is generated by the integrator under these conditions? 2. In order to control the slope of a ramp produced by an
. .- grator, the values of Vin, R and C may be varied. Assum-
7 -; a ﬁxed value for C of 10 HF, would it be better to have a
_tive large Vin with a correspondingly large value of R, or ' relatively small Vin with a relatively small corresponding 7, He of R? Explain your choice in terms of the current offset
V the summing point. 3 For the circuit of Figure 9A, determine Vout as a func—
.n of Vin. Also evaluate the input impedance of the circuit. V- in. FIGURE 9.A Circuit for problem 3. 4. For the circuit of Figure 9B, determine Vout as a func—
ﬁon of Vin. Also evaluate the input impedance of the circuit. 100 kg FIGURE 9.3 Circuit for problem 4. , 5. Write the expression for the output voltage in terms of
i the input voltages for the circuit shown in Figure 9C. , 6. Sketch a graph of V0th vs. Vin for the circuit shown in
é Figure 9D. Chapter9 Operational Ampliﬁers 211 FIGURE 9.C Circuit for problem 5. FIGURE 9.D Circuit for problem 6. 7. Sketch a graph of Vout+ vs. Vin and Vom, vs. Vin for the
circuit shown in Figure 9E. ' VouH- lN4l48 1N4l48 V Out— 27 k9
FIGURE 9.E Circuit for problem 7. 8. What is the function of the circuit of Figure 9F?
Determine the output-input relationship for the circuit for
an AC signal and a DC voltage input. >212 Chapter9 Operational Ampliﬁers 10 kg 13. Design operational ampliﬁer circuits which will gener—
ate the waveforms shown in Figure 91. Time FIGURE 9.F Circuit for problem 8. 9. What is the function of the circuit shown in Figure
96? Could it function if the diode were reversed? Explain. , B ‘
1 1N4148 ' Vom :
» vin ' .
E _ 0.01 uF ' FIGURE 9.G Circuit for problem 9. C 10. Design a circuit, using operational ampliﬁers, which
can multiply and divide. Note that the circuit should be capa-
ble of handling both negative and positive values. 11. Without elaborate circuitry, suggest how the input dif—
ference current (or input offset current), Ioﬂset, may be
evaluated. ,. mvmw—wwmw 12. Figure 9H is a square—wave generator. Derive the rela— tionship between frequency and the values of R and C. FIGURE 9'1 Circuit for problem 13' R 14. Set up an operational ampliﬁer circuit to solve the
——-+ -+7 +3=.
dt2 5dr x 0 15. The circuit shown in Figure 9] is a difference am-
ZR pliﬁer. What is the Vout in terms of the input voltages Va FIGURE 9.H Circuit for problem 12. and Vb? ‘ GURE 9.] Difference ampliﬁer circuit for problem 15. , i The circuit shown in Figure 9K is a difference ampli- ' ‘ , or more speciﬁcally, an instrumentation ampliﬁer. De—
.' e the transfer equation (Vout in terms of Vin and other Vomponents). What is the advantage of this circuit over that
. problem 15? FIGURE 9.K Instrumentation ampliﬁer circuit for
problem 16. Chapter9 Operational Ampliﬁers 213 17. Discuss why operational ampliﬁers should not be used
to directly drive loads greater than 20 mA (such asa lamp or relay). 18. Design a circuit which, at a rate of 0.2 Hz, turns on
and off a relay that in turn drives a 5 V, 1 A lamp using
components up to and including those discussed in this chapter. 19. Is it possible to design a single operational ampliﬁer
circuit with gain of exactly 96.000 using simple components?
Explain. 20. A non-inverting operational ampliﬁer circuit is con-
structed tohave a gain of 100 with an input signal of 1 kHz.
Would you expect the circuit to have the same gain with an
input signal of 1 MHZ? Explain. 21. You need to measure the voltage of a 100 pF very-
low—leakage capacitor which has one end connected to
ground. The voltage is known to be about 1 V. Using a digi-
tal voltmeter with 10 MD. input impedance and an opera—
tional ampliﬁer (choose one from Table 9.2), design a circuit
which can measure this voltage before considerably discharg- ing the capacitor. ...
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- Spring '09