Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
NTE266 NTE Electronics, Inc.	TRANS NPN 50V 500MA TO202	56
2N4402 NTE Electronics, Inc.	TRANS PNP 40V 600MA TO92	8793
NTE396 NTE Electronics, Inc.	TRANS NPN 350V 1A TO39	1360
2N6388 NTE Electronics, Inc.	TRANS NPN 80V 10A TO220AB	669
NTE2306 NTE Electronics, Inc.	TRANS PNP 160V 16A TO3PN	98
2N5301 NTE Electronics, Inc.	TRANS NPN 40V 30A TO3	52
NTE2319MP NTE Electronics, Inc.	TRANS NPN 450V 15A TO3	6
NTE290 NTE Electronics, Inc.	TRANS PNP 30V 800MA TO92	185
MJE15030 NTE Electronics, Inc.	TRANS NPN 150V 8A TO220AB	680
MJ10021 NTE Electronics, Inc.	T-NPN SI- HIV SW DARL	112
NTE2351 NTE Electronics, Inc.	TRANS NPN 80V 4A 3SIP	943
NTE51 NTE Electronics, Inc.	TRANS NPN 400V 4A TO220	412
NTE192A NTE Electronics, Inc.	TRANS NPN 50V 500MA TO92HS	126
2N3792 NTE Electronics, Inc.	TRANS PNP 80V 10A TO3	125
MPSA55 NTE Electronics, Inc.	TRANS PNP 60V 500MA TO92-3	31097
NTE290A NTE Electronics, Inc.	TRANS PNP 80V 500MA TO92	1419
NTE196 NTE Electronics, Inc.	TRANS NPN 70V 7A TO220	281
2N6725 NTE Electronics, Inc.	TRANS NPN 50V 1A TO237	240
2N6609 NTE Electronics, Inc.	TRANS PNP 140V 16A TO204	0
NTE293 NTE Electronics, Inc.	T-NPN SI AF PO PD .75W TO-92MOD	840

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