Part 2: The Varactor Diode 1. Construct the varactor resonant circuit shown in Figure 3-6. The circuit uses a reverse-bi

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Part 2 The Varactor Diode 1 Construct The Varactor Resonant Circuit Shown In Figure 3 6 The Circuit Uses A Reverse Bi 1 (60.68 KiB) Viewed 61 times

Part 2 The Varactor Diode 1 Construct The Varactor Resonant Circuit Shown In Figure 3 6 The Circuit Uses A Reverse Bi 2 (36.8 KiB) Viewed 61 times

Part 2: The Varactor Diode 1. Construct the varactor resonant circuit shown in Figure 3-6. The circuit uses a reverse-biased varactor to control the resonant frequency. C isolates the bias voltage from ground. Adjust the bias voltage to zero volts. Using the oscilloscope, set the function generator to 1.0 Vpp at a frequency of 100 kHz. Observe the signal across the inductor. At this frequency, the amplitude will be quite small. Increase the frequency slowly, and you should observe the signal rise suddenly to a maximum, then fall. The frequency of the maximum signal is the resonant frequency. Measure the resonant frequency and record it in the first space in Table 3-4. R 5.1 MS2 +15 V MV2109 V +1.0 V f 100 kHz BIAS PP R 10 ΚΩ le L 15 mH с 0.1 F Table 3-4 Resonant Varas Frequency. 0.0 V 1.0 V 2.0 V 4.0 V 8.0 V 15.0 V Figure 3-6 2. Increase the bias voltage to +1.0 V. Measure and record the new resonant frequency. Continue in this manner for each bias voltage given in Table 3-4. 3. Plot the response of the circuit in Plot 3-3. The independent variable is bias voltage so it is plotted on the x-axis as shown. The resonant frequency is plotted on the y-axis. Add the proper labels and title to your graph.

F. (H) 12 14 16 6 8 10 P(V) Plot 3-3 4. Measure the Q of the circuit. To do this, leave the bias voltage at a constant +15 y V Table 3-5. Then raise the frequency of the generator until the voltage across the inductor drops to 70.7% of the maximum (at resonance). This is the upper critical frequency. Sc. Measure and record this frequency in Table 3-5. Table 3-5 Parameter Measured Value Resonant frequency, Upper critical frequency, fa Lower critical frequency, fa Bandwidth, BW @ 5. Reduce the frequency of the generator until the voltage across the inductor drops to 70.7% of the maximum. This is the lower critical frequency, fc. Measure and record this frequency in Table 3-5. Then compute the bandwidth, BW, for the circuit by subtractingſ, from fe. Find Q for the circuit from the relation: e BW Record the calculated BW and Q in Table 3-5.