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Unformatted text preview: Experiment 10: Differential Amplifiers 1 Objective Differential amplifiers are designed to amplify the difference between two signals; thus, such amplifiers are capable of reducing noise that is common to both inputs. We can quantify the differential-mode versus common-mode gain in a quantity called the common-mode rejection ratio (CMRR). Differential amplifiers also lend themselves to use in feedback, though we will not explore that usage in this lab. A typical differential amplifier with a single-ended output is the op-amp. 2 Materials The items listed in table 1 will be needed. For this lab, assume all NPN transistors are identical 2N3904 BJTs and all PNP transistors are identical 2N3906 BJTs. Note: Be sure to answer the questions on the report as you proceed through this lab. The report questions are labeled according to the sections in the experiment. CAUTION: FOR THIS EXPERIMENT, THE TRANSISTORS CAN BECOME EXTREMELY HOT!!! Component Quantity LM741 op-amp 1 2N3904 NPN BJT 4 2N3906 PNP BJT 2 1 k resistor 2 5 . 1 k resistor 2 10 k resistor 2 . 1 F capacitor 1 Table 1: Components used in this lab Component I S (A) V A (V) 2N3904 NPN BJT 6 . 734 10- 15 74 . 03 2N3906 PNP BJT 1 . 41 10- 15 18 . 7 Table 2: Transistor properties 3 Procedure 3.1 Generating a differential signal Before building a differential amplifier, let us first generate a differential signal, which would require inverting...
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- Spring '08