23 Jun

BJT Operating Regions (Including Linear Region)

Note: In BJT, Linear Region and Active Region are generally considered the same region (used for amplification). However, in switching applications people often separately mention Cut-off, Linear (Active), and Saturation.

Parameter	Cut-off Region	Linear / Active Region	Saturation Region	Reverse Active Region
EB Junction	Reverse Biased	Forward Biased	Forward Biased	Reverse Biased
CB Junction	Reverse Biased	Reverse Biased	Forward Biased	Forward Biased
State	OFF	Partially ON	Fully ON	Rarely Used
Transistor Action	Open Switch	Amplifier	Closed Switch	Reverse Amplifier
Collector Current (IC)	≈ 0	IC = βIB	Maximum	Very Small
Base Current (IB)	0	Small	High	Small
Current Gain (β)	0	Maximum	Reduced	Very Low
VBE (Si)	< 0.7 V	≈ 0.7 V	0.7–0.8 V	Negative
VCE	Maximum	Moderate	0.1–0.3 V	High
Output Response	No Output	Linear Output	Constant Output	Rare
Application	Digital OFF	Amplification	Digital ON	Special Circuits

Linear (Active) Region Details

Conditions

For Silicon BJT:

VBE ≈ 0.7 V
VCE > VCE(sat)
IC = βIB

Characteristics

Feature	Linear Region
Amplification	Yes
Output proportional to Input	Yes
Used in Analog Circuits	Yes
Voltage Gain	High
Current Gain	High
Distortion	Minimum

Complete BJT Region Summary

Region	EB Bias	CB Bias	Use
Cut-off	Reverse	Reverse	Switch OFF
Active (Linear)	Forward	Reverse	Amplifier
Saturation	Forward	Forward	Switch ON
Reverse Active	Reverse	Forward	Rare

Switching vs Amplifier Regions

Application	Region Used
Digital Electronics	Cut-off + Saturation
Analog Amplifier	Active (Linear)
Power Amplifier	Active + Saturation
Logic Circuits	Cut-off + Saturation

RRB JE CBT2

BJT Bipolar Junction Transistor NPN Transistor PNP Transistor BJT Operating Regions BJT Regions Cut Off Region Active Region Linear Region Saturation Region Reverse Active Region Forward Active Region Transistor Biasing Junction Biasing Emitter Base Junction Collector Base Junction EB Junction CB Junction Transistor Amplifier Transistor Switch Analog Electronics Digital Electronics Semiconductor Devices Electronic Devices Electronics Engineering Electronic Circuits Basic Electronics Collector Current Base Current Emitter Current Current Gain Beta Alpha Beta Relationship VBE VCE VCE Saturation IC IB Relationship Common Emitter Configuration Common Base Configuration Common Collector Configuration Transistor Characteristics Input Characteristics Output Characteristics Transfer Characteristics Amplification Region Switching Region Linear Amplification Transistor as Amplifier Transistor as Switch Semiconductor Physics Electronic Components Circuit Theory Objective Electronics Electronics Notes Quick Revision Notes One Liner Electronics Competitive Exam Electronics Electronics MCQ Semiconductor MCQ RRB JE Electronics RRB JE CBT 2 SSC JE Electronics GATE Electronics ESE Electronics PSU Electronics Diploma Electronics BTech Electronics ECE Notes Technical Interview Questions Electronic Devices and Circuits Engineering Notes Railway JE Electronics Junior Engineer Electronics Electronics Previous Year Questions

Comments

BJT Operating Regions (Cut-off, Active/Linear, Saturation & Reverse Active)

BJT Operating Regions (Including Linear Region)

Linear (Active) Region Details

Conditions

Characteristics

Complete BJT Region Summary

Switching vs Amplifier Regions