The document discusses the Ebers-Moll model for modeling the behavior of a bipolar junction transistor (BJT). It describes the BJT model as using a diode model for the base-emitter junction and a dependent current source for the base-collector junction. The final and most accurate model discussed is the Ebers-Moll model, which can model the BJT in saturation, cutoff, and active modes.

1. BJT – Model
Yong Heui Cho @ Mokwon University
Some of slides are referred to:
[1] A. S. Sedra & K. C. Smith, Microelectronic Circuits.

2. 2
Electronic Circuits
7. Diode – Advanced Applications
8. BJT – Operational Principle
9. BJT – Model
10. BJT – Analysis of Bias

3. 3
Active Condition
• Collector Current(IC) = about mA
• CE Voltage(VCE) = VCC/2

4. 4
NPN TR as Switch
• NOT gate in digital circuit

5. 5
PNP TR as Switch

6. 6
iD = 0, vD ≤ VD0 iD = (vD - VD0) / rD , vD ≥ VD0
Diode Model
• Piecewise Linear Model
– B-E junction in BJT

7. 7
BJT Model
• Diode model: B-E junction
• Dependent current source: B-C junction

8. 8
Simple Ebers-Moll Model

9. 9
Final Model
Ebers-Moll Model at saturation Mode

10. 10
saturation mode
cutoff mode
Saturation Mode
• Active, cutoff, and saturation modes
• Small R region, full of carriers
active mode I-V curve