
Calculate the voltage gain, current gain, input impedance, and output impedance for the amplifier shown in Figure 19.131 in the textbook.

Answer to Problem 92P
The voltage gain, current gain, input impedance, and output impedance for the amplifier are
Explanation of Solution
Given Data:
Refer to Figure 19.131 in the textbook for the amplifier circuit.
From the given amplifier circuit, the internal resistance
Formula used:
Refer to Equation 19.73 in the textbook and write the expression for voltage gain of a amplifier in terms of hybrid parameters as follows:
Here,
Write the expression for current gain of the amplifier as follows:
Here,
Write the expression for input impedance of the amplifier as follows:
Calculation:
Redraw the given circuit as shown in Figure 1.
From Figure 1, write the expression for emitter current as follows:
Write the expression for base voltage from the circuit in Figure 1 as follows:
Write the expression for collector current as follows:
Write the expression for collector voltage as follows:
From Equation (7), substitute
Rearrange the expression as follows:
From Equation (2), substitute
Substitute 100 for
From Equation (6), substitute
Rearrange the expression as follows:
Rearrange the expression in Equation (5) as follows:
From Equations (7) and (9), substitute
Rearrange the expression as follows:
Substitute 100 for
Simplify the expression as follows:
From Equation (1), substitute
From Equation (9), substitute
Rearrange the expression as follows:
Substitute 100 for
From Equation (3), substitute
Consider output voltage
Apply KVL to the input loop for the circuit in Figure 2 as follows:
Substitute 1 for
Apply KCL at the output node for the circuit in Figure 2 as follows:
Substitute 1 for
Rearrange the expression as follows:
From Equation (12), substitute
Substitute 100 for
Write the expression for output impedance of the amplifier as follows:
Substitute 1 for
Conclusion:
Thus, the voltage gain, current gain, input impedance, and output impedance for the amplifier are
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Chapter 19 Solutions
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