July 2020 StudentZone Quiz Solution

Question 1:

Replace capacitor CF with a smaller value (0.01uF) and re-measure the response curve with the Network Analyzer instrument or AC Sweep simulation. Explain the effect of the new capacitor value in the response that you see.

Answer 1:

Replace the CF (C2) capacitor value to 0.01uF in the circuit provided within the lab activity (Figure 5)

Now plot the output of the circuit (2+) using the AC sweep analysis. The output is presented in the plot below (blue trace). The output for 0.047uF capacitor value is used as reference (red trace).


As we might notice, the higher 3-dB frequency fH has increased after the modification of the capacitor CF value. This behavior is validated by the equation shown in the lab activity:

Where the higher 3-dB frequency is inversely proportional with the value of CF.