# Finding Input/Output Impedance of a CE Amplifier: Practical Methods

• phabos
In summary, the purpose of finding the input/output impedance of a CE amplifier is to determine the transferability of signals and its impact on the amplifier's stability and performance. The two most common practical methods for finding this impedance are the voltage divider method and the short-circuit current method. The voltage divider method involves measuring the input and output voltage and calculating the ratio, assuming that the output impedance is larger than the input impedance. The short-circuit current method involves measuring the input current and calculating the ratio with the input voltage, assuming the opposite. However, the accuracy of these methods can be affected by factors such as stray capacitance, parasitic resistance, and load impedance.
phabos
how can i find input and output impedance of a ce amplifier- (voltage divider )..suggest practical methods?

The basic steps are:

1. Determine the small-signal hybrid-pi model parameters for the transistor
2. Write the KVL loop equations for the input and the output (bias circuits and hybrid-pi)
3. Manipulate algebraically to the input and output driving-point impedances

## 1. What is the purpose of finding the input/output impedance of a CE amplifier?

The input/output impedance of a CE amplifier is important because it determines how easily the amplifier can transfer signals from the input to the output. It also affects the stability and performance of the amplifier.

## 2. What are the practical methods for finding the input/output impedance of a CE amplifier?

The two most common practical methods for finding the input/output impedance of a CE amplifier are the voltage divider method and the short-circuit current method. Both methods involve measuring the voltage and current at the input and output of the amplifier and using these values to calculate the impedance.

## 3. How does the voltage divider method work?

The voltage divider method involves applying a test voltage at the input of the amplifier and measuring the output voltage. The ratio of these two voltages can then be used to calculate the input impedance. This method assumes that the output impedance of the amplifier is much larger than the input impedance.

## 4. How does the short-circuit current method work?

The short-circuit current method involves shorting the output of the amplifier and measuring the current at the input. The ratio of the input voltage to the input current can then be used to calculate the input impedance. This method assumes that the input impedance of the amplifier is much larger than the output impedance.

## 5. What factors can affect the accuracy of the measured input/output impedance?

The accuracy of the measured input/output impedance can be affected by factors such as stray capacitance, parasitic resistance, and load impedance. These factors can introduce errors in the measured values and should be taken into consideration when using practical methods to find the input/output impedance of a CE amplifier.

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