Print Name : Email ID : ECE 2660 Test #1 9/22/2016 All answers must be recorded on the answer page (page 2). You must do all questions on the exam. For Part 4 you must show all your work and write your answer in the box on the answer sheet. For all questions, you may use a calculator, but not a laptop computer. You are allowed 1 page of handwritten notes, which must be stapled to this test at the end of the test period. Pledge : Signed : Page 1 of 12
Answers Part 1: (15 points total) 1) A, B, C, D 2) A, B, C, D 3) A, B, C, D Part 5 (10 points total) 12) Vo= Part 2: (10 points total) 4) Vo= Part 3: (30 points total) 5) A, B, C, D 6) A, B, C, D 7) A, B, C, D, E 8) A, B, C, D, E 9) A, B, C, D, E 10) A, B, C, D, E Part 4: (10 points total) 11) Part 6 (15 points) 13) A, B, C, D 14) A, B, C, D 15) A, B, C, D Part 7 (10 points) a0= a1= b1= a2= b2= a 3 = b3= a4= b4= R1= R2= Total Score Page 2 of 12
Part 1 You are given the following circuit, Figure 1. The next 3 questions refer to this figure. Assume that the opamp has infinite gain, unlimited bandwidth. Figure 1 1) If +V and -V are +/- 10V respectively, and R1 and R2 are each 20K ohms, which one of the following is true? A. If Vin is a sinusoidal source of magnitude 1 volt and 0 degrees phase, Vout is a sinusoidal waveform of twice the amplitude and the same phase. B. If Vin is a sinusoidal source of magnitude 1 volt and 0 degrees phase, Vout is a sinusoidal waveform of the same amplitude and 180 degrees phase. C. If Vin is a sinusoidal source of magnitude 1 volt and 0 degrees phase, Vout is -1 Volt. D. If Vin is a sinusoidal source of magnitude 11 volts, the output will be a sinusoidal waveform of 5.5 Volts 2) If +V and V are +/- 10V respectively, and R1 = 20K, R2 = 1K, which one of the following is true? A. The maximum input signal that can be amplified without distortion is 0.5 volts magnitude. B. The maximum input signal that can be amplified without distortion is 0.1 volts, with an output of 20 V volts Pk.-Pk. C. The maximum undistorted output is 10 volts amplitude and the phase is the same as the input voltage. D. A square wave cannot be suitably amplified by this circuit unless the amplitude is less than 0.1 volts. Page 3 of 12
3) Under the assumptions listed in question 1, which statement best describes the system shown in Figure 1: A. The system is definitely nonlinear and could behave with memory. B. The system definitely has memory and could behave linearly. C. The system is definitely linear and could behave memorylessly. D. The system is definitely memoryless and could behave nonlinearly. Part 2 4) For the op-amp circuit in the figure below, find V0 as a function of V1 and V2. You can assume that the op-amp is operating as an ideal op-amp. Page 4 of 12
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Part 3 For the circuit shown in the picture on the previous page, use the pinout diagram of the TL072 to answer the following questions: 5) The function of the circuit is: A. Schmitt trigger B. Inverting amplifier stage C. Integrator D. Differentiator 6) If the frequency of an output signal from a circuit is 1 khz, an appropriate time scale for the virtual bench oscilloscope would show a few more than one, less than 10) periods across the 10 divisions on the screen. An appropriate time per division would be: A. 10 µsec per division B. 5 msec per division C. 100 msec per division D. 500 µsec per division For questions 7-10, match the descriptions to the schematics for the figures below: A )Summing Amplifier B) Non-inverting amplifier C) Integrator D) Difference Amplifier E) Schmidt Trigger 7. Page 6 of 12
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Part 4 11) Find Values of R1 and R2 such that the noise immunity is +/-0.5 volts. You must show all of your work for this problem on this page. Page 8 of 12
Part 5 12) The op-amp circuit in the figure below contains an ideal current source and two ideal voltage sources. Find the numerical value of Vo in Volts. You can assume that the op-amp is operating as an ideal op-amp. Page 9 of 12
Part 6 Suppose you are given the following magnitude spectrum of the input x(t) of a system: 13) What statement best describes what we know about this signal: A. The signal is periodic and odd symmetric B. The signal is periodic and even symmetric C. The signal is periodic and we don t know if it is odd or even symmetric D. The signal is nonperiodic 14) If the system is linear, which of the following is necessarily true about the output of the system : A. The magnitude of DC term is zero B. The fundamental frequency has the largest magnitude C. If the fundamental has magnitude 10, then the second harmonic has magnitude 5 D. All of the above are true. 15) Let this signal be input into a system with frequency response HH(ωω) = 3000ππππ. If the fundamental ωω frequency is 500 Hz, what is magnitude and phase of the third harmonic of the output? A. Magnitude of -1, phase of π/2 relative to positive cosine B. Magnitude of 2, phase of -π/2 relative to positive cosine C. Magnitude of 1, phase of -π/2 relative to the input D. Magnitude of 2π, phase of - π/2 relative to the input Page 10 of 12
Part 7 16) Given the expression for x(t) below, find the trigonometric Fourier Series coefficients up to n=4. xx(tt) = 3ssssssssss + 4cccccc2ωωωω + 5cos (3ωωωω + ππ 4 ) Page 11 of 12
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