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Electric Circuits, 9th Edition P73

Electric Circuits, 9th Edition P73. Designed for use in a one or two-semester Introductory Circuit Analysis or Circuit Theory Course taught in Electrical or Computer Engineering Departments. Electric Circuits 9/e is the most widely used introductory circuits textbook of the past 25 years. As this book has evolved over the years to meet the changing learning styles of students, importantly, the underlying teaching approaches and philosophies remain unchanged. | 696 Two-Port Circuits Example 18.5 If more than two units are connected in cascade the a parameters of the equivalent two-port circuit can be found by successively reducing the original set of two-port circuits one pair at a time. Example 18.5 illustrates how to use Eqs. 18.74-18.77 to analyze a cascade connection with two amplifier circuits. Analyzing Cascaded Two-Port Circuits Two identical amplifiers are connected in cascade as shown in Fig. 18.11. Each amplifier is described in terms of its h parameters. The values are in 1000 il z12 0.0015 z21 100 and 10.25 X 10 6 rt12 aÎla12 F flÎ2fl22 5 X 10 4 10 -10 -10 2 0.095 il a21 rt21flil 22 21 10 6 5 x 10 4 -0.01 -10 6 9.5 x 10 9S Solution The first step in finding V2 Vs t0 convert from h parameters to a parameters. The amplifiers are identical so one set of a parameters describes the amplifiers . a22 a21a i2 tt22a22 -10 6 10 -10-2 2 1.1 x 10 4. From Table 18.2 ah -A z z2i 0.05 c . 5 x 10 4 100 2 - 11 21 -1000 -io n 100 rt21 22 21 -100 x 10 6 ---- ------ -10 6S. 100 a22 - inn 10 2- 21 100 Next we use Eqs. 18.74-18.77 to compute the a parameters of the cascaded amplifiers V2 _ L fln a12 a22Zs _104_ 10.25 X IO-6 9.5 X 10 9 500 104 0.095 1.1 X 10 4 500 104 0.15 0.095 0.055 _ 105 3 33 333.33. fl 12rt21 25 X IO 8 -10 10 6 Thus an input signal of 150 zV is amplified to an output signal of 5 V. For an alternative approach to finding the voltage gain V2 Vg see Problem 18.41. Practical Perspective 697 assessment problem Objective 3 Know how to analyze a cascade interconnection of two-port circuits 18.7 Each element in the symmetric bridged-tee circuit shown is a 15 il resistor. Two of these bridged tees are connected in cascade between a de voltage source and a resistive load. The de voltage source has a no load voltage of 100 V and an internal resistance of 8 il.The load resistor is adjusted until maximum power is .