Ham Radio General Class Practice Test

Which of the following is an advantage of using a Schottky diode in an RF switching circuit compared to a standard silicon diode?

1. Lower capacitance

2. Lower inductance

3. Longer switching times

4. Higher breakdown voltage

The correct answer is: Lower capacitance

Using a Schottky diode in an RF switching circuit offers the advantage of lower capacitance compared to a standard silicon diode. Schottky diodes are known for their fast switching capabilities and low forward voltage drop, which is largely due to their metal-semiconductor junction. This junction produces less charge storage than the p-n junction found in silicon diodes. Lower capacitance is particularly beneficial in RF applications where high-frequency signals are involved. Higher capacitance can lead to unwanted signal distortion and reduced efficiency in switching applications because it can slow down the diode's response time, affecting how quickly it can turn on and off. Therefore, the use of a Schottky diode, with its inherently lower capacitance, allows for faster operation and better performance in RF circuits. The other options do not accurately represent the advantages of Schottky diodes in this context. Schottky diodes typically have lower breakdown voltages than silicon diodes, which is not an advantage in this application. Additionally, they do not provide longer switching times; in fact, they are characterized by shorter switching times. Inductance is generally a property related to the physical layout and construction of the circuit rather than the characteristics of the diode itself.