Which of the following diode is used in ultra-high speed switching electronic circuits?

Question

UnlockIAS · Accepted Answer

Correct — C, Tunnel diode. Because of quantum tunneling across a very narrow, heavily-doped p-n junction, a tunnel diode (Esaki diode) responds in picoseconds and shows negative differential resistance, making it well suited to ultra-high-speed switching and microwave-frequency oscillator circuits.

Why the other options are wrong — (a) Designed to operate in reverse breakdown for stable voltage regulation/reference — not a switching device.  (b) Used as a voltage-controlled variable capacitor in tuning circuits and oscillators, not for switching.  (d) Also switches quickly (it is a majority-carrier device with no minority-carrier storage delay) and is prized for low forward-voltage-drop rectification and RF applications — but the 'ultra-high-speed' (picosecond-range) switching credited here comes from the tunnel diode's quantum-tunneling mechanism.

Concept: A tunnel diode (Esaki diode) is a heavily-doped p-n junction diode, made so narrow that electrons can quantum-mechanically 'tunnel' straight across the depletion region without needing extra activation energy. This produces a region of negative differential resistance and an extremely fast response, making it useful in ultra-high-speed switching and microwave oscillator circuits.

State PCS 2022 Q48 — Science & Technology PYQ with Answer

State PCS 2022 Q48 — Science & Technology PYQ with Answer