Diode – Operational Principle

Yong Heui Cho @ Mokwon University

Some of slides are referred to:[1] A. S. Sedra & K. C. Smith, Microelectronic Circuits.

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Electronic Circuits

2. Introduction to Smart Sen-sors3. Basic Circuit Theory

4. Diode – Operational Principle5. Diode – V/I

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Diode Circuit• A diode is widely used to control

current of electric circuits.

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Diode• Diode = anode + cathode• Simple switch modeling– Electronic switch

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Diode Representa-tion

• P-type and N-type semiconduc-tors– P: positive, N: negative

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Doping Process• Adding impurities to silicon (Si)

dramatically changes electrical behaviors of semiconductor.–N-type: P, As– P-type: B, Ga

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Diode Cross Section• P-N junction– P-type & N-type doped semiconductor

• Carrier: electron (-), hole (+)

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Forward & Reverse Bias• Bias: DC voltage to set up a de-

vice

forward bias

reverse bias

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Depletion Region• Insulating region within a doped

semiconductor material

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Basic Circuit

mAk

RVI R

R

101010

10100 RIV RR

forward bias reverse bias

0DV 0DI

• Ideal diode approximation

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Rectifier• Ideal diode approximation

Output Waveform

Equivalent Circuits Waveform of

VD

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• Ohmmeter– Real case: ideal diode mode is not

suitable.

R Measurement

OL: Open Line

forward reverse

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V Measurement• Voltmeter– Cut-in voltage: almost 0.7 [V]

forward

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LED• Light-Emitting Diode• Various colors: R, G, B, W

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GaN Blue Diode• Nagoya University & Nichia Corporation