Varactor Diode Applications and Concepts

The video tutorial explains varactor diodes, also known as varicap diodes, which function as voltage-controlled capacitors. It covers their electrical symbol, functionality, and how they act as capacitors when reverse-biased. The relationship between junction capacitance and reverse voltage is discussed, highlighting the inverse relationship. The video compares the capacitance of conventional diodes with varactor diodes, emphasizing the high capacitance ratio of varactor diodes. Finally, it explores applications of varactor diodes in tuned circuits and voltage-controlled oscillators, demonstrating how they can adjust resonant frequencies.

What is another name for a varactor diode?

• Zener diode

• Varicap

• Schottky diode

• Tunnel diode

In which bias mode does a varactor diode exhibit high junction capacitance?

• Forward bias

• Reverse bias

• Both forward and reverse bias

• No bias

What forms the insulator in a diode acting as a capacitor in reverse bias?

• N-type material

• Metal plates

• P-type material

• Depletion layer

What happens to the junction capacitance as the reverse voltage increases?

• It increases

• It decreases

• It remains constant

• It fluctuates

Which diode has a low capacitance ratio?

• 1N4001 conventional diode

• NTE618 varactor diode

• Schottky diode

• Zener diode

What is the capacitance range of the NTE618 varactor diode at 1.2 volts?

• 30 to 4 picofarads

• 420 to 459 picofarads

• 144 to 192 picofarads

• 46 to 61 picofarads

Which component in a circuit can be used to adjust the reverse voltage across a varactor diode?

• Inductor

• Potentiometer

• Fixed resistor

• Capacitor

What is the formula to calculate the resonance frequency in a circuit with a varactor diode?

• 2π√LC

• 1/LC

• 2πLC

• 1/2π√LC

What is the maximum frequency range of a circuit with an inductor of 0.1 millihenries and a varactor diode capacitance of 20 picofarads?

• 742 kHz

• 5.0 MHz

• 1.2 MHz

• 3.56 MHz

What is a common application of varactor diodes?

• Signal mixers

• Power amplifiers

• Voltage-controlled oscillators

• Rectifiers