MOD2P2 - SEMICON DIODE AND DIODE EQUIVALENT CIRCUITS

PN Junction

It is formed when an n-type and a p-type materials are brought together.

It is formed at the boundary between the two regions.

Depletion Region

that the region near the PN junction is depleted of charge carriers (both electrons and holes) due to diffusion across the junction

Barrier Potential

potential difference of the electric field across the depletion region. It is also the amount of energy required to move the free electrons through the electric field.

Forward Bias

when the anode is more positive than the cathode.

This removes the depletion region

Reverse Bias

the condition when the anode is more negative than the cathode.

Since the depletion region widens, it can be expected that no current flow will result.

Reverse Bias

Actually, a small current will flow because of the minority carriers.

Reverse Bias

The __________ voltage forces the minority carriers to drift across the junction and cause a small leakage current or reverse saturation current.

Knee Voltage

voltage wherein the sudden increase in current starts

Breakdown Voltage

It is the maximum voltage that can be handled by the junction diode.

Breakdown Voltage

It is also known as the peak reverse voltage or peak inverse voltage.

Avalanche

multiplication of conduction electrons and results in a very high reverse current that can damage the PN structure because of excessive heat dissipation.

Static Resistance, RD

It is the resistance of the diode at the quiescent operating point.

Average AC Resistance

resistance associated with the device when a large signal is used as an input to produce a broad swing

Transition-Region/Depletion-Region Capacitance

capacitance considered in the reverse-bias region

Diffusion/Storage Capacitance

capacitance considered in the forward-bias region

Diode Equivalent Model

combination of circuit elements that best represents the actual characteristics of a semiconductor diode under a specific operating condition.

Ideal Diode Model (First Approximation)

An ideal diode approximates the actual behavior of a practical semiconductor diode by representing it as a simple switch

Simplified Diode Model (Second Approximation)

The diode when forward-biased has some threshold voltage and has no resistance.

Piecewise