This document discusses diodes and their characteristics. It defines forward and reverse bias of a diode based on whether the P-side or N-side is more positive. It shows the ideal diode circuit symbol and its I-V characteristics, acting as an open circuit when reverse biased and a closed circuit when forward biased. It discusses determining if a diode is forward or reverse biased using open and short circuit tests based on the voltage and current. The document also covers diode resistance levels and introduces Zener diodes, providing examples of calculating voltages in diode circuits.

1. Diodes
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Department of Electronics and Communication Engineering

2. Diodes
• The simplest and most fundamental nonlinear
circuit element is the diode
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P N

3. Diodes
• FB: If P-side is more positive than N-side then it
is FB
• RB: If N-side is more positive than P-side then it
is RB
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P N

4. Diodes
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5. The Ideal Diode
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(a) diode circuit symbol
(b) i–v characteristic;
(c) equivalent circuit
in the reverse
direction;
(d) equivalent circuit in the forward direction.

6. Region of operation
• Open circuit Test
• If VD>0 FB
• If VD<0 RB
• Short circuit Test
• If ID>0 FB
• If ID<0 RB
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7. Problem #1
• Determine the region of operation of diode
Apply SC Test
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8. Problem #1
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A

9. Diode Characteristics
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




  10 TVVeII 

10. RESISTANCE LEVELS
• Static resistance, RD=VD/ID
• Dynamic resistance,
• For small signal, diode acts as a resistor
• If ID is small rd is large
• If ID is large rd is small
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11. Problem #2
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12. Zener diode
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13. Problem #3
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14. Problem #4
• Find the power rating of the Zener diode
• VOC=12V
• VOC>VZ Zener diode is in breakdown region
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15. Problem #4
• Find the power rating of the Zener diode
• VZ=VL=10V
• IL=10/3=3.33mA
• I=(16-10)/1mA=6mA
• IZ=I-IL=6-3.33=2.67mA
• PZ=VZ*IZ ANIL PRASAD DADI/ECE/ANITS

16. Problem #5
• Find the voltage across 1K
Options:
A) 6V B) 5V
C) 7.5V D) 6.5V
• VOC=5V
• VOC<VZ Zener diode is in breakdown region
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17. Problem #6
• Find the output voltage
if VD2=0.7V
• I=(3.7-0.7)/2mA=1.5mA
• VOC=1x1.5+0.7=2.2V
• VOC<VZ Zener diode is not in breakdown region
• VO=2.2V
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