NEETS Module 8, Chapter 1

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TURNTABLEAMPLI-FIERSPEAKERTURNTABLEAMPLI-FIERAMPLI-FIERSPEAKERSPEAKERTURNTABLEAMPLI-FIERAMPLI-FIERAMPLI-FIERSPEAKERNTS080108Figure 1-8.—Adding stages of amplification.Whether an amplifier is one of a series in a device or a single stage connected between two otherdevices (top view, figure 1-8), there must be some way for the signal to enter and leave the amplifier. Theprocess of transferring energy between circuits is known as COUPLING. There are various ways ofcoupling signals into and out of amplifier circuits. The following is a description of some of the morecommon methods of amplifier coupling.Direct CouplingThe method of coupling that uses the least number of circuit elements and that is, perhaps, the easiestto understand is direct coupling. In direct coupling the output of one stage is connected directly to theinput of the following stage. Figure 1-9 shows two direct-coupled transistor amplifiers.1-10
V BB7VQ213VOUTPUTR1Q1R2R3INPUTR4R5R6Vcc6V10V15VNTS080109Figure 1-9.—Direct-coupled transistor amplifier.Notice that the output (collector) of Q1 is connected directly to the input (base) of Q2. The networkof R4, R5, and R6 is a voltage divider used to provide the bias and operating voltages for Q1 and Q2. Theentire circuit provides two stages of amplification.Direct coupling provides a good frequency response since no frequency-sensitive components(inductors and capacitors) are used. The frequency response of a circuit using direct coupling is affectedonly by the amplifying device itself.Direct coupling has several disadvantages, however. The major problem is the power supplyrequirements for direct-coupled amplifiers. Each succeeding stage requires a higher voltage. The load andvoltage divider resistors use a large amount of power and the biasing can become very complicated. Inaddition, it is difficult to match the impedance from stage to stage with direct coupling. (Impedancematching is covered a little later in this chapter.)The direct-coupled amplifier is not very efficient and the losses increase as the number of stagesincrease. Because of the disadvantages, direct coupling is not used very often.RC CouplingThe most commonly used coupling in amplifiers is RC coupling. An RC-coupling network is shownin figure 1-10.1-11
Page 1 and 2: CHAPTER 1AMPLIFIERSLEARNING OBJECTI
Page 3 and 4: ANTENNADETECTOR(SEPARATES AUDIO FRO
Page 5 and 6: FREQUENCY RESPONSE OF AMPLIFIERSIn
Page 7 and 8: shape and frequency. In some cases,
Page 9: +V CCR1OUTQ1VBBINR2VEEFigure 1-7.
Page 13 and 14: Figure 1-11 shows an impedance-coup
Page 15 and 16: impedance-matching device is like t
Page 17 and 18: Input Signal Impedance =Input Signa
Page 19 and 20: FEEDBACKSIGNALFEED-BACKNETWORKINPUT
Page 21 and 22: The feedback network in this amplif
Page 23 and 24: C2C1Q1R3OUTPUTR1R2VCCINPUTVBBAC2C1Q
Page 25 and 26: Figure 1-22.—Ideal frequency resp
Page 27 and 28: If you do not remember how a FET wo
Page 29 and 30: C3R1C1Q1R3R4R5R7C5+ V CCQ2C2R2C4R6+
Page 31 and 32: The CLASS OF OPERATION of a transis
Page 33 and 34: COUPLING is used to transfer a sign
Page 35 and 36: MAXIMUM POWER TRANSFER occurs betwe
Page 37 and 38: VCCHIGH INPUT Z2k Ω - 500k ΩLOW O
Page 39 and 40: T1Q1T2R1+ V CCQ2NTS0801I-19ANSWERS

NEETS Module 8, Chapter 1

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