Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
NTE2365 NTE Electronics, Inc.	TRANS NPN 800V 15A TO3PBL	408
2N404 NTE Electronics, Inc.	TRANS PNP 24V 100MA TO5	637
MPSA20 NTE Electronics, Inc.	SMALL SIGNAL BIPOLAR TRANSISTOR	123103
NTE289AMP NTE Electronics, Inc.	TRANS NPN 80V 500MA TO92	16
NTE38 NTE Electronics, Inc.	TRANS PNP 350V 2A TO66	97
NTE243 NTE Electronics, Inc.	TRANS NPN 80V 8A TO3	294
NTE186A NTE Electronics, Inc.	TRANS NPN 40V 3A TO202M	144
NTE2333 NTE Electronics, Inc.	TRANS NPN 450V 6A TO220	493
NTE2339 NTE Electronics, Inc.	TRANS NPN 800V 3A TO220	652
NTE2654 NTE Electronics, Inc.	TRANS NPN 230V 15A TO3P	192
NTE164 NTE Electronics, Inc.	TRANS NPN 700V 1A TO3	117
MMBTA56 NTE Electronics, Inc.	0.5A, 80V, PNP	873068
2N6727 NTE Electronics, Inc.	TRANS PNP 40V 2A TO237	248
NTE2676 NTE Electronics, Inc.	TRANS NPN 600V 10A TO3PIS	1520
TIP30C NTE Electronics, Inc.	POWER BIPOLAR TRANSISTOR	1582
2N3054 NTE Electronics, Inc.	TRANS NPN 55V 4A TO66	411
NTE2350 NTE Electronics, Inc.	TRANS PNP 120V 50A TO3	226
NTE123A-100 NTE Electronics, Inc.	TRANS NPN 40V 800MA TO18 100PK	4
NTE2533 NTE Electronics, Inc.	TRANS NPN 800V 25A TO3PBL	28
2N5686 NTE Electronics, Inc.	TRANS NPN 80V 50A TO3	14

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