Introduction:
Using Op-Amps for Radio Frequency Design
The purpose of this lab is to construct a practical Colpitts RF Oscillator circuit with MultiSIM. The frequency of output waveforms will be measured using a virtual oscilloscope. Students will gain an understanding of the effects biasing resistors on the output frequency of oscillator.

1. Review the document Week 4 - RF Oscillator.pdf

2. Calculate the value of RG in order to produce the following output voltages (peak-to-peak).
Vout RG
5V
7V
10V
12V
15V

3. Construct the Colpitts Oscillator in Figure 2 of the PDF document in Multisim.

4. Using the values of RG from the table, run the simulations to confirm the output voltage, Vout.

5. Using Agilent Oscilloscope, plot the output waveform of Vout for each case and measure the frequency of the output. Take the screen capture for each measurement.

6. Reverse the polarity of the diodes and redo steps 4 and 5.
RG Measured Frequency (in Hz) Vout (Forward Biased) Vout (Reverse Biased)

7. Observe the differences in the output voltage and the frequencies between forward and reverse biased diode settings and explain the significance of diodes in the operations of this oscillator.

8. Answer the following questions:
1. Describe the operations of the Colpitts oscillator circuit and explain how it helps in generating clean sinusoidal output?
2. How does the two diodes help in providing linear input to the voltage follower circuit?
3. Discuss how the resistor Ros can be setup to perform soft clipping operations.

9. Verify all calculations from analysis and measurements from simulation. Save the results along with the table and paste the screen captures in the word document. Make sure to answer the questions.