Question

Which one of the following is not a mode of operation of a Gunn diode?
1. LSA oscillation mode
2. Stable amplification mode
3. Bias circuit oscillation mode
4. Non-linear mode 

Answer 1

Correct Answer - Option 4 : Non-linear mode 

Gunn diode:

• A Gunn diode does not contain any typical PN diode junction like the other diodes, but it consists of two electrodes.
• It is also called a Transferred Electronic Device.
• It is a negative differential resistance device, which is frequently used as a low-power oscillator to generate microwaves.
• It consists of only an N-type semiconductor in which electrons are the majority charge carriers.

 

A Gunn diode can operate in four modes:

Gunn Oscillation Mode: In this region, the region is unstable because of the cyclic formation of either the accumulation layer or the high field domain.

Stable amplification mode: This mode is defined in the region where the product of frequency times length is about 10⁷ cm/s and the product of doping times length is between 10¹¹ and 10¹² /cm² 

LSA oscillation mode: This mode is defined in the region where the product of frequency times length is above 10⁷ cm/s and the quotient of doping divided by the frequency is between 2 × 104 and 2 × 105

Bias circuit oscillation mode: This mode occurs only when there is either Gunn or LSA oscillation, and it is usually at the region where the product of the frequency times length is too small to appear in the figure.

∴ Non-linear is not a mode of the Gunn Diode.