Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2N699 PBFREE Central Semiconductor	THROUGH-HOLE TRANSISTOR-SMALL SI	0
2N5232A PBFREE Central Semiconductor	TRANS NPN 50V 0.1A TO-92	4055
CMPT5087 TR PBFREE Central Semiconductor	TRANS PNP 50V 0.05A SOT23	3144
CMPT2907A TR PBFREE Central Semiconductor	TRANS PNP 60V 0.6A SOT-23	25001
CZT3906 TR PBFREE Central Semiconductor	TRANS PNP 40V 0.2A SOT223	7737
2N6055 PBFREE Central Semiconductor	TRANS NPN 60V 8A TO-3	157
CMPT5089 TR PBFREE Central Semiconductor	TRANS NPN 25V 0.05A SOT-23	8903
CXT5551 TR PBFREE Central Semiconductor	TRANS NPN 180V 0.6A SOT89	466390000
2N5089 PBFREE Central Semiconductor	TRANS NPN 25V 0.05A TO-92	2298
CXT4033 TR PBFREE Central Semiconductor	TRANS PNP 80V 1A SOT89	391
2N3955 Central Semiconductor	THROUGH-HOLE TRANSISTOR-SMALL SI	0
2N4126 PBFREE Central Semiconductor	TRANS PNP 25V TO-92	2269
CMPT2222A TR PBFREE Central Semiconductor	TRANS NPN 40V 0.6A SOT-23	43759
CMUT2907A TR PBFREE Central Semiconductor	TRANS PNP 60V 0.6A SOT523	2080
TIP32C PBFREE Central Semiconductor	THROUGH-HOLE TRANSISTOR-BIPOLAR	0
2N6052 PBFREE Central Semiconductor	TRANS PNP 100V 12A TO-3	93
TIP29A SL PBFREE Central Semiconductor	THROUGH-HOLE TRANSISTOR BIPOLAR	0
CMPT2484 BK PBFREE Central Semiconductor	TRANS NPN 60V 0.05A SOT23	0
2N2222 PBFREE Central Semiconductor	TRANS NPN 30V 0.8A TO-18	2205
TIP29A PBFREE Central Semiconductor	THROUGH-HOLE TRANSISTOR BIPOLAR	0

Transistors - Bipolar (BJT) - Single

1. Overview

Bipolar Junction Transistors (BJTs) are three-terminal semiconductor devices that use both electron and hole charge carriers. They form the foundation of analog electronics through their ability to amplify signals and control current flow. BJTs remain critical in modern electronics for applications ranging from audio amplifiers to power management circuits, offering superior linearity and robustness in switching operations.

2. Main Types & Functional Classification

Type	Functional Characteristics	Application Examples
NPN Transistor	Majority carriers: electrons. Requires positive base current for conduction.	Low-noise amplifiers, digital logic circuits
PNP Transistor	Majority carriers: holes. Conducts with negative base current.	Power supply circuits, motor controllers
High-Frequency BJT	Optimized for RF/microwave signal amplification (f_T > 100 MHz)	Wireless communication systems, radar
Power BJT	High current/voltage ratings (I_C > 1A, V_CE > 50V)	Switch-mode power supplies, motor drives

3. Structure & Composition

BJTs consist of three doped semiconductor regions forming two p-n junctions:

Emitter: Heavily doped region emitting charge carriers
Base: Thin, lightly doped middle region controlling carrier flow
Collector: Moderately doped region collecting carriers

Manufactured using silicon (common) or germanium (historic) with planar processing technology. The structure forms either NPN (n-type emitter/base/collector) or PNP configuration, with metal contacts for external connections.

4. Key Technical Specifications

Parameter	Description	Importance
Current Gain (h_FE)	Ratio of collector to base current (10-1000)	Determines amplification capability
Transition Frequency (f_T)	Frequency at which current gain drops to 1	Limits high-frequency performance
Max Collector Current (I_Cmax)	Maximum allowable continuous collector current	Defines power handling capability
Breakdown Voltage (V_CEO)	Max voltage between collector and emitter	Prevents device failure under stress
Saturation Voltage (V_CEsat)	Voltage drop in fully conducting state	Affects power efficiency in switching

5. Application Areas

Consumer Electronics: Audio amplifiers, LED drivers
Automotive: Engine control units, electric vehicle inverters
Industrial: PLCs, motor controllers
Telecommunications: RF power amplifiers, fiber optic transceivers
Aerospace: Avionics systems, satellite transponders

6. Leading Manufacturers & Products

Manufacturer	Product Series	Key Specifications	Typical Use
ON Semiconductor	2N3904	hFE: 100-300, fT: 300 MHz	General-purpose switching
Infineon	BC547	VCEO: 50V, ICmax: 100mA	Analog signal amplification
STMicroelectronics	2SD2656	ICmax: 15A, VCEO: 80V	Power inverter applications
Diodes Inc.	BFR93A	fT: 10 GHz, Noise Figure: 2dB	High-frequency front-end amplifiers

7. Selection Guidelines

Determine operating frequency: Select fT > 3 target frequency
Power requirements: Ensure Icmax and VCEO exceed circuit requirements by 20%
Thermal considerations: Calculate power dissipation (P=V_CE I_C)
Package type: TO-92 for low power, TO-220 for high-power applications
Environmental factors: Consider temperature ratings for industrial/military use

8. Industry Trends

Future developments include:

High-frequency BJTs operating beyond 100 GHz for 6G communication
Integrated BJT-MOSFET hybrid devices (BiCMOS) for mixed-signal applications
Wide-bandgap materials (SiC/GaN) for higher power density
Miniaturization through chip-scale packaging
Improved thermal management solutions for automotive applications