Gunn Diode Oscillator Quiz - Microwave Engineering

1 What is the fundamental operating principle of a Gunn diode?

Avalanche breakdown and carrier multiplication Transferred electron effect (Gunn effect) Quantum tunneling through the barrier PN junction forward bias conduction

2 Which semiconductor material is most commonly used for fabricating Gunn diodes?

Silicon (Si) Gallium Arsenide (GaAs) Germanium (Ge) Indium Phosphide (InP)

3 In the two-valley model of GaAs, what is the approximate energy separation between the central valley (Γ) and satellite valleys (L)?

0.01 eV 0.31 eV 1.12 eV 2.5 eV

4 What is the threshold electric field for the onset of negative differential resistance in GaAs?

100 V/cm 1,000 V/cm 3,000 V/cm 10,000 V/cm

5 What phenomenon occurs when electrons transfer from the high-mobility central valley to the low-mobility satellite valleys?

Positive differential resistance Negative differential resistance (NDR) Superconductivity Photovoltaic effect

6 What is the typical frequency range of operation for Gunn diode oscillators?

1 MHz - 10 MHz 100 MHz - 500 MHz 1 GHz - 100 GHz 1 THz - 10 THz

7 Which mode of operation in a Gunn diode is characterized by the formation of high-field domains that travel from cathode to anode?

Stable amplification mode LSA (Limited Space-charge Accumulation) mode Transit-time domain mode Quenched domain mode

8 What is the primary advantage of using the LSA mode in Gunn diode oscillators?

Higher efficiency and higher frequency operation Lower noise figure Simpler biasing circuit Lower thermal resistance

9 In a Gunn diode oscillator circuit, what is the purpose of the resonant cavity?

To provide DC bias isolation only To determine the operating frequency and provide feedback To act as a heat sink To prevent reverse breakdown

10 What is the typical DC-to-RF conversion efficiency of a Gunn diode oscillator?

Less than 1% 5% - 10% 20% - 30% 50% - 60%

11 Which of the following is a major limitation of Gunn diode oscillators?

Extremely low output power Low DC-to-RF conversion efficiency and temperature sensitivity Inability to operate at microwave frequencies Requirement for cryogenic cooling

12 What is the "Gunn frequency" in a transit-time domain mode oscillator approximately equal to?

vₛ / L, where vₛ is the saturation velocity and L is the active layer length c / λ, where c is the speed of light and λ is the wavelength 1 / (2π√(LC)) of the external circuit qE/m, where q is electron charge, E is electric field, and m is effective mass

🔬 Gunn Diode Oscillator Quiz

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