06-08-2013, 12:32 PM
COMMON DRAIN AMPLIFIER
Aim:
To design a common drain amplifier and to measure the gain, input resistance and output
resistance with and without Bootstrapping.
Apparatus required:
1. Transistor
- BC-107
2. Regulated Power supply
3. Audio Frequency Oscillator
4. Resistors - 4.7KΩ, 2.7KΩ, 1MΩ
5. Capacitor - 1μ F
6. CRO
7. Bread board and connecting wires
Theory:
Here input is applied between gate and source & output between source and Drain. Here
Vs = VG + VGS. When a signal is applied to JFET gate via Cin,VG varies with the signal. As VGS
is fairly constant and Vs varies with Vi. Here output voltage follows the change in the signal
voltage applied to the gate, the circuit is also called as Source follower
Procedure:
1. Connect the circuit as shown in the circuit diagram
2. Set Vs= 50 mv in AFO
3. Keeping the input voltage constant, vary the frequency from 0 Hz to1MHz in regular
steps and note down the corresponding output voltage.
4. Plot the graph: gain Vs Frequency
5. Calculate the bandwidth from the Graph
Result:
Thus a common drain amplifier is designed and the gain, input resistance and output
resistance are calculated using the measured parameters.