I. DESCRIPTION AND OBJECTIVES
This laboratory presents a basic practical summary of operational amplifiers (op-amps) and will provide the opportunity to become familiar with their behavior from an ideal and non-ideal perspective.
II. GENERAL DISCUSSION
An op-amp is a three-port device having two inputs and one output. It was invented to simplify the design of inverting and non-inverting DC amplifiers by the simple control of external negative feedback. This deceptively simple building block is to analog electronics what nand or nor gates are to digital electronic circuits: it reduces analog circuit design to a simple problem of determining suitable external feedback and interconnecting networks without the complication of having to know what's going on inside the op-amp itself. Treating the op-amp as ideal is often all that is necessary to use it in practice, provided we skillfully appreciate the limitations imposed by basic device parameters that would typically include: non-infinite open-loop gain, frequency response expressed by slew rate, single-pole roll-off frequency and its related gain-bandwidth product GBP, non-infinite input port resistances and non-zero output resistance; power-supply limiting or railing due to finite power supply voltages. Although the op-amp is employed in a truly impressive array of many different circuits, all are based in part on one or both of the following two fundamental circuit configurations, the inverting and non-inverting DC amplifiers. You will gain an appreciation of the power of the op-amp as a basic building block along with some of its inherent limitations by investigation of these two basic circuits.
Construct the circuit shown in Fig. 1. using an AD741 op-amp. R2 should be 10k. Determine the following for R1 = 1k, and R1 = 10k:
Observe power-supply limiting and log what these voltage rails are. Measure and accurately plot the amplitude and phase response vs. frequency. Frequency should be measured with a counter, amplitude in RMS from a DVM. Measure the slew rate.
From your data, construct a simple Bode Plot showing both plots for the two different circuit gains. Discuss the meaning of the gain-bandwidth product relationship and verify it from your data. Discuss your results for slew-rate. Numeric data should be discussed with realistic precision using only as many significant figures as your data warrants.
IV. INVERTING CONFIGURATION
Modify your circuit to realize an inverting amplifier and repeat the measurements taken earlier for the non-inverting configuration . Discuss all differences you observe between the two configurations.
You should address these questions in your lab report.
The lab report should be proof-read and well written. Check out format.html if you are unsure what is expected. Your lab report should include (at least):