Lab 14 TF EIM
The Common Emitter
Circuit
- Construct the common emitter amplifier circuit below according to your type of emitter.
- Calculate all the R and C values to use in the circuit such that
- mA DC with no input signal
- V
- to prevent burnout
- mA
- Draw a load line using the -vs- from the previous lab 13. Record the value of or .
- Set a DC operating point I^{\prime}_C so it will amplify the input pulse given to you. Some of you will have sinusoidal pulses others will have positive or negative only pulses.
- Measure all DC voltages in the circuit and compare with the predicted values.
- Measure the voltage gain as a function of frequency and compare to the theoretical value.
- Measure and at about 1 kHz and compare to the theoretical value.
- Measure and as a function of frequency with removed.
Questions
- Why does a flat load line produce a high voltage gain and a steep load line a high current gain? (10 pnts)
- What would be a good operating point an an common emitter amplifier used to amplify negative pulses?(10 pnts)
- What will the values of , , and be if the transistor burns out resulting in infinite resistance. Check with measurement.(10 pnts)
- What will the values of , , and be if the transistor burns out resulting in near ZERO resistance (ie short). Check with measurement.(10 pnts)
- Predict the change in the value of if is increased from 10 to 50 (10 pnts)
- Sketch the AC equivalent circuit of the common emitter amplifier.(10 pnts)