Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2N6714 NTE Electronics, Inc.	TRANS NPN 30V 2A TO237	72
MPSL51 NTE Electronics, Inc.	SMALL SIGNAL BIPOLAR TRANSISTOR	0
NTE377 NTE Electronics, Inc.	TRANS NPN 80V 10A TO220	39
NTE103 NTE Electronics, Inc.	T-NPN GE-AF PREAMP DR PO	183
NTE2648 NTE Electronics, Inc.	T-NPN SI PWR AMP 230V 1A TO-220	407
NTE289 NTE Electronics, Inc.	TRANS NPN 30V 800MA TO92	296
NTE129MCP NTE Electronics, Inc.	TRANS PNP 80V 1A TO39	40
NTE288 NTE Electronics, Inc.	TRANS PNP 300V 500MA TO92	0
NTE284MP NTE Electronics, Inc.	TRANS NPN 180V 16A TO3	7
2N4870 NTE Electronics, Inc.	TRANS PNP UNIJUNCTION TO92	44
NTE2411 NTE Electronics, Inc.	TRANS PNP 150V 500MA SOT23	0
NTE184MP NTE Electronics, Inc.	TRANS NPN 80V 4A TO126	20
MJ11033 NTE Electronics, Inc.	TRANS PNP 120V 50A TO3	136
NTE331MP NTE Electronics, Inc.	TRANS NPN 100V 15A TO220	4
BU406D NTE Electronics, Inc.	T-NPN SI- HIV SW	239
NTE60MP NTE Electronics, Inc.	TRANS NPN 140V 20A TO3	8
NTE2327 NTE Electronics, Inc.	TRANS NPN 450V 500MA TO126	313
NTE52 NTE Electronics, Inc.	TRANS NPN 450V 5A TO3	222
NTE389 NTE Electronics, Inc.	TRANS NPN 750V 4A TO3	97
NTE2341 NTE Electronics, Inc.	TRANS NPN 80V 1A TO92	380

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