Circuit Design: - Electrical Engineering and Computer Science



Pre-Lab Exercises

Intro-Lab

Circuit Design:

You should have read the lab handout before beginning the Pre-lab exercises, specifically the Appendix section on the operational amplifier.

Differential Amplifier:

Figure 1 shows a 3op-amp differential amplifier design using the LM741 chip. Derive the characteristic equation given below. This will give you experience with simple linear circuits. All you need is the equations of an op-amp and Ohm’s Law, and the Appendix of the Intro Lab should help as well as your book.

Characteristic Equation:

Vo = (V2-V1) (R3/R2)(1+ (2R1/R))

Now, consider the monolithic Differential Amplifier Chip AD620. You should download its data sheet from:



Design the amplifier for a gain of 50. See the data sheet and consult your circuit kit item sheet, available from the course website, for a list of available resistors and use these to for the specifics of the circuit design.

The pinout diagram for the AD620 is given in the data sheet. It is a 1 op-amp design to function the same as the three op-amp design above. It uses one resistance Rg to determine the gain. Pin 5 is the circuit ground and +/- Vs is the power supply voltage and should be set to +/-12 Volts respectively.

1. Draw the circuit, its wiring diagram and write its output function.

2. Sketch the output if the input is a sine wave from -1 to 1 V and T=10 ms.

Low Pass Filter:

Consider the op-amp chip LM741 and download the data sheet from:



Use the data sheet and the Appendix from the Intro Lab to design a lowpass filter with a cutoff frequency of 1 kHz. There should be an inventory list of your capacitor kit available from the course website.

3. Draw the circuit, its wiring diagram and write its output function.

4. Write the differential equation for your modified circuit and solve it.

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Figure 1: Instrumentation Amplifier using 3 LM741 OP-AMPs

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