Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
NTE398 NTE Electronics, Inc.	TRANS PNP 150V 2A TO220	610
NTE2349 NTE Electronics, Inc.	TRANS NPN 120V 50A TO3	234
NTE154 NTE Electronics, Inc.	TRANS NPN 300V TO39	352
NTE197 NTE Electronics, Inc.	TRANS PNP 70V 7A TO220	51
NTE397 NTE Electronics, Inc.	TRANS PNP 300V 1A TO39	65
14-3459 NTE Electronics, Inc.	GLASS CLOTH TAPE-PLYGLASS 108 FT	12
NTE179MP NTE Electronics, Inc.	TRANS PNP 40V 25A TO3	8
NTE251 NTE Electronics, Inc.	TRANS NPN 100V 20A TO3	371
TIP34A NTE Electronics, Inc.	TRANS PNP 60V 10A TO218	775
NTE187 NTE Electronics, Inc.	TRANS PNP 60V 3A TO202	69
NTE183 NTE Electronics, Inc.	TRANS PNP 60V 10A TO127	25
NTE2354 NTE Electronics, Inc.	TRANS NPN 800V 10A TO3P	1124
NTE16004 NTE Electronics, Inc.	TRANS PNP 75V 2A TO39	115
2N3439 NTE Electronics, Inc.	TRANS NPN 350V 1A TO39	0
2N3904 NTE Electronics, Inc.	T-NPN SI-GEN PUR AMP SW	6643
NTE2321 NTE Electronics, Inc.	TRANS NPN 40V 500MA 14DIP	341
D40K2 NTE Electronics, Inc.	T-NPN SI DARLINGTON	536
NTE241 NTE Electronics, Inc.	TRANS NPN 80V 4A TO220	157
2N6284 NTE Electronics, Inc.	TRANS NPN 100V 20A TO204	32
2N4923 NTE Electronics, Inc.	TRANS NPN 80V 1A TO225AA	48

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