Solved: Assume that the op amp in the circuit shown is ideal. a) Find the output voltage

Assume that the op amp in the circuit shown is ideal. a) Calculate v0 for the following values of vs: 0.4,2.0,3.5, -0.6, -1.6, and -2.4 V. b) Specify the range of vs required to avoid amplifier saturation.

The source voltage vs in the circuit in Assessment Problem 5.1 is -640 mV. The 80 kil feedback resistor is replaced by a variable resistor Rx. What range of Rx allows the NOTE: Also try Chapter Problems 5.8 and 5.9. inverting amplifier to operate in its linear region?

a) Find v0 in the circuit shown if va = 0.1 V and vb = 0.25 V. b) If vb = 0.25 V, how large can va be before the op amp saturates? c) If va = 0.10 V, how large can vb be before the op amp saturates? d) Repeat (a), (b), and (c) with the polarity of vb reversed.

Assume that the op amp in the circuit shown is ideal. a) Find the output voltage when the variable resistor is set to 60 kfl. b) How large can Rx be before the amplifier saturates?

a) In the difference amplifier shown, vb = 4.0 V. What range of values for vu will result in linear operation? b) Repeat (a) with the 20 kO resistor decreased to 8 kCt.

The inverting amplifier in the circuit shown has an input resistance of 500 kH, an output resistance of 5 kfl, and an open-loop gain of 300,000. Assume that the amplifier is operating in its linear region. a) Calculate the voltage gain (v0/vg) of the amplifier. b) Calculate the value of v in microvolts when vs= IV. c) Calculate the resistance seen by the signal source (vg). d) Repeat (a)-(c) using the ideal model for the op amp.

A circuit designer claims the circuit in Fig. P5.7 will PRACTICAL produce an output voltage that will vary between PSPICE 5 as Vfr varies between 0 and 5 V. Assume the op MULTISIM am p is ideal. a) Draw a graph of the output voltage v0 as a function of the input voltage v for 0 : Vq ^ 5 V. b) Do you agree with the designer's claim'

a) Design an inverting amplifier using an ideal op amp that has a gain of 3. Use a set of identical resistors from Appendix H. b) If you wish to amplify a 5 V input signal using the circuit you designed in part (a), what are the smallest power supply signals you can use?

The op amp in the circuit in Fig. P5.9 is ideal. MULTISIM a ) ^ind the range of values for a in which the op amp does not saturate. b) Find i() (in microamperes) when a = 0.272. Figure P5.9 12 kfl a50 kfl 1.6 kfl -AAWW50 k n 6 250 rnV 6.4 kfl t t l?n i io kn

Refer to the circuit in Fig. 5.12, where the op amp PSPICE is assumed to be ideal. Given that Ra = 4 kfl, .ULTISIM R h = 5kll i ^ = 2Qka ^ VA S 200 mV, vb = 150 mV, vc = 400 mV, and Vcc = 6 V, specify the range of Rf for which the op amp operates within its linear region.

The op amp in Fig. P5.12 is ideal. PSPICE a ) wha t circuit configuration is shown in this figure? b) Find vQ if 4 V. = IV , vh = 1.5 V, and c) The voltages va and vc remain at 1 V and - 4 V, respectively. What are the limits on vb if the op amp operates within its linear region? Figure P5.12 44 kfl VA, + 27.5 kfl 220 kfl AAA0a W ^ + 80 kfl vh v 53.3 kfl

Design an inverting-summing amplifier so that va = -(3 + 5vh + 4 + 2vd). DE5IGN PROBLEM MULTISIM Start by choosing a feedback resistor (Rf) from Appendix H. Then choose single resistors from Appendix H or construct resistor neworks from resistors in Appendix H to satisfy the design values for /?a , /?b, Rc, and i?d. Draw your final circuit diagram.

a) The op amp in Fig. P5.14 is ideal. Find va if PSPICE ? ; a = 4 V, vb = 9 V, vc= \3 V, and vd = 8 V. 4ULTISIM b) Assume v.A vc, and vL\ retain their values as given in (a). Specify the range of v.x such that the op amp operates within its linear region. Figure P5.17 Figure P5.14 40 kil VvV + 22kft VW 220 kil 'VW ii, T T Okil

Tlie 220 ki l feedback resistor in the circuit in Fig. P5.14 is replaced by a variable resistor Rf. The voltages v.d- vd have the same values as given in Problem 5.14(a). a) What value of Rf will cause the op amp to saturate? Note that 0 < Rf < oo. b) When Rf has the value found in (a), what is the current (in microamperes) into the output terminal of the op amp?

The op amp in the circuit of Fig. P5.16 is ideal. PSPICE a \ -yvhat 0 p am p circuit configuration is this? MULTISIM b) Calculate vu.

The op amp in the circuit of Fig. P5.17 is ideal. a) What op amp circuit configuration is this? b) Find va in terms of vs . c) Find the range of values for vs such that vn does not saturate and the op amp remains in its linear region of operation.

The op amp in the circuit shown in Fig. P5.18 is ideal. PSPI" a) Calculate va when v., equals 4 V. MULTISIM ' " ." n b) Specify the range of values of vs so that the op amp operates in a linear mode. c) Assume that v equals 2 V and that the 63 kil resistor is replaced with a variable resistor. What value of the variable resistor will cause the op amp to saturate? Figure P5.18 63 kil AAAi.'527kn

a) Design a non-inverting amplifier with a gain of 4. Use resistors from Appendix H. You might need to combine resistors in series and in parallel to get the desired resistance. Draw your final circuit, b) If you use 12 V power supplies for the op amp, what range of input values will allow the op amp to stay in its linear operating region?

The op amp in the circuit shown in Fig. P5.21 is PSPICE ideal. The signal voltages v.. and vb are 800 mV and MULTISIM .. , . . . , 400 mv, respectively. a) What circuit configuration is shown in the figure? b) Calculate va in volts. c) Find /a and /b in microamperes. d) What are the weighting factors associated with va and vb? Figure P5.21 110 kO 'VW 47kft

The circuit in Fig. P5.22 is a noninverting summing PROBLEM amplifier. Assume the op amp is ideal. Design the PSPICE circuit so that MULTISIM v<> = ya + 2^ + 3vc. a) Specify the numerical values of Ra and Rc. b) Calculate /a, /b, and /c (in microamperes) when va = 0.7 V, vb = 0.4 V, and uc = 1.1 V.

The op amp in the noninverting summing amplifier of Fig. P5.23 is ideal. a) Specify the values of Rf, Rb, and Rc so that v0 = 6v.A + 3vh + 4vc.

a) Use the principle of superposition to derive Eq. 5.22. b) Derive Eqs. 5.23 and 5.24.

The resistors in the difference amplifier shown PSPICE in Fig. 5.15 are Ka = 24kO, Rb = 75 kll, MULTISIM Rc = 130k a an d ^ - 120 kH. The signal voltages v.d and vb are 8 and 5 V, respectively, and Vcc = 20 V. a) Find v(>. b) What is the resistance seen by the signal source ya? c) What is the resistance seen by the signal source vb?

The op amp in the circuit of Fig. P5.26 is ideal. What value of R{ will give the equation v() = 5 - 4vu, for this circuit?

Design the difference-amplifier circuit in Fig. P5.27 so that v(l = 10( - va), and the voltage source vb sees an input resistance of 220 kfi. Specify the values of Ra ,Rb and Rt using single resistors or combinations of resistors from Appendix H. Use the ideal model for the op amp.

The op amp in the adder-subtracter circuit shown in PSPICE pig. P5.28 is ideal. MULTISIM a) Find v0 when va = 1 V, vb = 2 V, vc = 3 V, and Vd = 4 V. b) If va, vb, and vd are held constant, what values of vc will not saturate the op amp?

Select the values of Ra and R{ in the circuit in DESIGN Fig. P5.29 so that va = 5000(;b - Q. Use single resistors or combinations of resistors from Appendix H.The op amp is ideal.

The resistor R in the circuit in Fig. P5.31 is adjusted until the ideal op amp saturates. Specify Rt in kilohms. Figure P5.31 1.6 kO 18 V 5.6 kH

The op amp in the circuit of Fig. P5.32 is ideal. (a) Plot \(v_o\) versus \(\alpha\) when \(R_f=4 R_1\) and \(v_g=2 \mathrm{~V}\). Use increments of 0.1 and note by hypothesis that \(0 \leq \alpha \leq 1.0\). (b) Write an equation for the straight line you plotted in (a). How are the slope and intercept of the line related to \(v_g\) and the ratio \(R_f / R_1\) ? (c) Using the results from (b), choose values for \(v_g\) and the ratio \(R_f / R_1\) such that \(v_o=-6 \alpha+4\).

In the difference amplifier shown in Fig. P5.33, what range of values of Rx yields a CMRR > 1000? Figure P5.33

In the difference amplifier shown in Fig. P5.34, compute (a) the differential mode gain, (b) the common mode gain, and (c) the CMRR. Figure P5.34 1 kO ^ L < i 25kfl r ^ f 10V ^"S-iov 124 kO

Assume that the ideal op amp in the circuit seen in Fig. P5.35 is operating in its linear region. a) Show that v0 = [(/?, + R2)/Rx\vs . b) What happens if R1 oo and R2 - 0? c) Explain why this circuit is referred to as a voltage follower when Z?j = oo and R2 = 0.

The voltage vg shown in Fig. P5.36(a) is applied to PSPICE tn e inverting amplifier shown in Fig. P5.36(b). 1ULTISIM <-,,, , , , --1 1 Sketch v versus f, assuming the op amp is ideal.

Tlie signal voltage vg in the circuit shown in Fig. P5.37 PSPICE j s described by the following equations: MULTISIM * ve = 0, 0, vg = 10 sin(ir/3)/ V, 0 < / < oo. Sketch va versus r, assuming the op amp is ideal.

a) Show that when the ideal op amp in Fig. P5.38 is operating in its linear region, . 3V8 * = -Rb) Show that the ideal op amp will saturate when R(VCC ~ 2vg) R* = 3vg

Assume that the ideal op amp in the circuit in PSPICE Fig. P5.39 is operating in its linear region. MULTISIM a) Calculate the power delivered to the 16 kO resistor. b) Repeat (a) with the op amp removed from the circuit, that is, with the 16 kfit resistor connected in the series with the voltage source and the 48 kft resistor. c) Find the ratio of the power found in (a) to that found in (b). d) Does the insertion of the op amp between the source and the load serve a useful purpose? Explain.

The two op amps in the circuit in Fig. P5.41 are PSPICE ideal. Calculate v\ and vo2. MULTISIM Figure P5.41 15 V 15 V 10 V 4,2 f5kf t

The op amps in the circuit in Fig. P5.42 are ideal. PSPICE a) Find/ a . ULTISIM b) Find the value of the left source voltage for which /n = 0.

Repeat Assessment Problem 5.6, given that the PSPICE inverting amplifier is loaded with a 500 ft resistor

Assume the input resistance of the op amp in PSPKE Fig. P5.44 is infinite and its output resistance is zero. MULTISIM a) Find v0 as a function of vg and the open-loop gain A. b) What is the value of v0 if vg - 1 V and A = 150? c) What is the value of v0 if vg = 1 V and A - oo? d) How large does A have to be so that v{) is 99% of its value in (c)?

The op amp in the noninverting amplifier circuit of PSPICE Fig. P5.45 has an input resistance of 560 kft, an outWLTISIM p U t res { s t anc e 0 f kO, and an open-loop gain of 50,000. Assume that the op amp is operating in its linear region. a) Calculate the voltage gain (v()/vg). b) Find the inverting and noninverting input voltages vn and vp (in millivolts) if vg 1 V. c) Calculate the difference (vp - vn) in microvolts when Vg ~ 1 V. d) Find the current drain in picoamperes on the signal source vR when vg = 1 V. e) Repeat (a)-(d) assuming an ideal op amp.

a) Find the Thevenin equivalent circuit with respect to the output terminals a,b for the inverting amplifier of Fig. P5.46. The dc signal source has a value of 880 mV. The op amp has an input resistance of 500 kft, an output resistance of 2 kft and an open-loop gain of 100,000. b) What is the output resistance of the inverting amplifier? c) What is the resistance (in ohms) seen by the signal source vs when the load at the terminals a,b is 330 ft?

Repeat Problem 5.46 assuming an ideal op amp.

Derive Eq. 5.60.

Suppose the strain gages in the bridge in Fig. 5.21 PRACTICAL have the value 120 ft 1%. The power supplies PERSPECTIVE r r r to the op amp are 15V, and the reference voltage, vrc{, is taken from the positive power supply. a) Calculate the value of Rf so that when the strain gage that is lengthening reaches its maximum length, the output voltage is 5 V. b) Suppose that we can accurately measure 50 mV changes in the output voltage. What change in strain gage resistance can be detected in milliohms?

a) If percent error is defined as PRAOICAL PERSPECTIVE PSPICE MULTISIM % error = approximate value true value - 1 x 100,show that the percent error in the approximation of v in Problem 5.50 is AR (R + Re) % error = 7 TTTT X 100. R (R + 2R{) b) Calculate the percent error in va for Problem 5.50.

Assume the percent error in the approximation of PRACTICAL vt) in the circuit in Fig. P5.50 is not to exceed 1%. PERSPECTIVE " PSPICE What is the largest percent change in R that can be MULTisM tolerated?

Assume the resistor in the variable branch of the PRACTICAL bridge circuit in Fig. P5.50 is R PERSPECTIVE n L R + AR. AR instead of PSPICE MULTISIM a) What is the expression for v() if AR R? b) What is the expression for the percent error in va as a function of R, i?f , and AR1 c) Assume the resistance in the variable arm of the bridge circuit in Fig. P5.50 is 9810 fi and the values of R, R( , and vm are the same as in Problem 5.50(b). What is the approximate value of va'? d) What is the percent error in the approximation of v(} when the variable arm resistance is 9810 a ?