# Op-Amps and ICs

Please refer to the attachment for the figures mentioned in these questions.

1. When a pulse is applied to an op-amp, the output goes from -40 V to +5 V in 0.6 microseconds. What is the slew rate?

2. A certain diff-amp (differential amplifier) has a differential voltage gain of 1500 and a common-mode gain of 0.5. Determine the CMRR and express it in dB.

3. A certain diff-amp (differential amplifier) has a differential voltage gain of 3000 and a CMRR of 90 dB. A 1 V rms, 60 Hz common-mode interface signal appears on both inputs. Determine the rms interference voltage on the output.

4. Consider the non-inverting amplifier shown in figure 1. Determine the closed-loop voltage gain.

5. Using figure 1 find the input impedance using A = 200,000 and Zin = 3 Mohms (open-loop).

6. If the input voltage for a circuit of figure 2 is +0.1 V DC, what is the voltage between the (-) and (+) terminals?

7. A low pass filter has a critical frequency of 100 kHz. What is its bandwidth?

8. A high pass filter has a R = 2.6 kohms and C = 0.0020 microF. What is its critical frequency?

9. Using figure 2 find the input impedance using A = 150,000 and Zin = 2 Mohms (open-loop).

10. The midrange open-loop gain of a certain op-amp is 150 dB. Negative feedback reduces this gain by 60 dB. What is the closed-loop gain?

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#### Solution Summary

This posting contains the solution to the given problems.

Op-Amps and ICs

Please see the attachment for referred figures.

1. The midrange open gain of a certain op-amp is 100,000. If the open loop critical frequency is 75 Hz, what is the open loop gain at 1 KHz?

2. A certain op-amp has three internal amplifier stages with the following gains and critical frequencies: A1 = 50 dB at f1 = 1000Hz, A2 = 70 dB at f2 = 100Hz, A3 = 30 dB at f3 = 25,000Hz. Determine the open loop midrange dB gain.

3. For the op-amp in problem 2, determine the phase lag when f = f1.

4. The op-amp in figure 1 has a unity-gain bandwidth of 3 MHz and the RF = 100Kohms and Ri = 5Kohms. Find the bandwidth.

5. The op-amp in figure 2 has a unity-gain bandwidth of 3 MHz and the RF = 200Kohms and Ri = 4Kohms. Find the bandwidth.

6. Using figure 3 find the output voltage if the 3 input voltages are 1V, 2V, and 3V (starting with the top resistor and going down) and RF = 15Kohms

7. Using figure 3 with RF = 15 kohms and 3 input voltages are 1V, 2V, and 3V (starting with the top resistor and going down) find the current through RF.

8. A low pass filter has a critical frequency of 1kHz. What is its bandwidth?

9. A high pass filter has a R = 3kohms and C = 0.0020microF. What is its critical frequency?

10. What is the roll-off rate of a 3rd order low pass filter?

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