Question

The type of noise that would interfere much with the high frequency transmission is

• A. Shot
• B. Transit time
• C. Flicker
• D. White

Hint:

Noise Types vs Frequency. Flicker (1/f): Dominant at low frequencies. Shot/Thermal (White): Flat spectrum over wide range. Transit-Time: Significant only at very high frequencies (when transit time \(\approx\) 1/f).

Answer 1

The Correct Option is B

Different types of noise affect electronic circuits and transmissions differently depending on frequency: - Shot Noise: Caused by the discrete nature of charge carriers crossing a potential barrier (like in diodes/transistors)
Its power spectral density is generally flat (white) up to very high frequencies
- Flicker Noise (1/f noise): Dominant at very low frequencies, its power spectral density decreases with increasing frequency
It's generally negligible at high frequencies
- White Noise (e
g
, Thermal Noise): Has a flat power spectral density across a wide range of frequencies
Thermal noise is present at all frequencies, but doesn't inherently interfere *more* at high frequencies compared to low frequencies within its flat range
- Transit-Time Noise: Occurs in semiconductor devices (like transistors) at high frequencies when the time taken by charge carriers to travel through the device becomes comparable to the period of the signal frequency
This leads to variations in the carrier flow and induces noise that becomes significant at high frequencies (e
g
, microwave range)
Therefore, transit-time noise specifically becomes a major limiting factor and source of interference in high-frequency transmissions and devices