Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
MMBT3906 NTE Electronics, Inc.	T-PNP SI- GEN PUR AMP	2144
NTE287 NTE Electronics, Inc.	TRANS NPN 300V 500MA TO92	358
NTE2675 NTE Electronics, Inc.	TRANS NPN 800V 6A TO3PN	1549
2N3442 NTE Electronics, Inc.	TRANS NPN 140V 10A TO204	0
2N3714 NTE Electronics, Inc.	TRANS NPN 80V 10A TO3	142
NTE62 NTE Electronics, Inc.	TRANS NPN 900V 3A TO3	19
2N5320 NTE Electronics, Inc.	T-NPN SI- SWITCH	130
NTE72 NTE Electronics, Inc.	TRANS NPN 80V 10A TO61	8
NTE2330 NTE Electronics, Inc.	TRANS NPN 55V 4A TO3P	195
2N5884 NTE Electronics, Inc.	TRANS PNP 80V 25A TO3	4759
NTE2302 NTE Electronics, Inc.	TRANS NPN 800V 5A TO3P	712
2N6059 NTE Electronics, Inc.	TRANS NPN 100V 12A TO3	116
NTE123A-5 NTE Electronics, Inc.	TRANS NPN 40V 800MA TO18 5PK	19
NTE27 NTE Electronics, Inc.	TRANS PNP 45V 60A TO3	17
NTE387MP NTE Electronics, Inc.	TRANS NPN 150V 50A TO3	8
NTE2550 NTE Electronics, Inc.	TRANS NPN 400V 10A TO220	323
NTE226MP NTE Electronics, Inc.	TRANS PNP 35V 2A TO66	28
NTE384 NTE Electronics, Inc.	TRANS NPN 350V 7A TO66	469
NTE342 NTE Electronics, Inc.	T-NPN RF PO 7W TYP TO-220 TYPE	634
2N3417 NTE Electronics, Inc.	TRANS NPN 50V 500MA TO92-3	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