HW_10(2) - EE 438 Homework #10 Multistage Audio Amplifier...

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EE 438 Homework #10 Multistage Audio Amplifier The circuit diagram of a simple three stage audio amplifier designed to drive an 8 speaker is shown on the next page. The β ’s of the three ZETEX transistors used in the circuit are indicated on the diagram. Transistors Q 2 and Q 3 are connected together in an arrangement that is called a Darlington pair. The two transistors operate together to act like a single transistor that has an effective β = β 2 + β 3 + β 2 × β 3 . This results in a very large effective β that can range well into the tens of thousands. In the following analysis combine Q2 and Q3 into a single Darlington equivalent that has the effective β noted above. In the constant voltage drop model of the Darlington pair the value of the V BE battery is the sum of the V BE drops of the two BJT’s in the pair. The equivalent V BE of the Darlington pair in the circuit of this problem is V BE = 0.6 + 0.7 = 1.3V.
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This note was uploaded on 10/26/2009 for the course EE 438 taught by Professor Cardwell during the Spring '08 term at University of Texas.

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HW_10(2) - EE 438 Homework #10 Multistage Audio Amplifier...

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