1. {20 Points} By proper choice of the components and the R1, C1, R2, C2, transfer function of this circuit can be made independent of frequency. In that case the circuit is called a and the components and can compensated attenuator, R1 C1 be used as an oscilloscope probe. In this application, the signal from a circuit being viewed on an oscilloscope is attenuated, and the input impedance of the oscilloscope is by the probe so that it does not distort the “compensated” measurement. Assume that in Figure 2, and represent the probe, while R1 C1 R2 and represent the oscilloscope input. For an oscilloscope with an input C2 = 2.2[M] and a probe with = 8.3[M] , it has been found that when the R2 R1 oscilloscope probe is connected to a square wave, that the image on the oscilloscope screen will be square when = 46[pF]. C1 a) Find the capacitance of the oscilloscope, C2. b) In the lab, we use probes that are called probes”. What would you “ten-times call the probe in this case? Room for extra work 2. {40 Points} Assume ideal op amps. a) Find as a function of vA vI. b) Find as a function of vB vI. c) Find as a function of iA vI. Room for work 3. {40 Points} The transfer function for an audio circuit has the straight-line H(f) approximation to the magnitude Bode plot shown in Figure 1. The frequency axis in this plot is not drawn to scale. The non-zero slope values are shown. Find f1. Find f2.
1. {20 Points} By proper choice of the components R1, C1, R2, and C2, the transfer function of this circuit can be made independent of frequency. In that case the circuit is called a compensated attenuator, and the components R1 and C1 can be used as an oscilloscope probe. In this application, the signal from a circuit being viewed on an oscilloscope is attenuated, and the input impedance of the oscilloscope is “compensated” by the probe so that it does not distort the measurement. Assume that in Figure 2, R1 and C1 represent the probe, while R2 and C2 represent the oscilloscope input. For an oscilloscope with an input R2 = 2.2[M] and a probe with R1 = 8.3[M] , it has been found that when the oscilloscope probe is connected to a square wave, that the image on the oscilloscope screen will be square when C1 = 46[pF]. a) Find the capacitance of the oscilloscope, C2. b) In the lab, we use probes that are called “ten-times probes”. What would you call the probe in this case? Room for extra work 2. {40 Points} Assume ideal op amps. a) Find vA as a function of vI. b) Find vB as a function of vI. c) Find iA as a function of vI. Room for work 3. {40 Points} The transfer function H(f) for an audio circuit has the straight-line approximation to the magnitude Bode plot shown in Figure 1. The frequency axis in this plot is not drawn to scale. The non-zero slope values are shown. Find f1. Find f2.
ECE3355_Exam1_Fall2016.docx