Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
NTE2328 NTE Electronics, Inc.	TRANS NPN 200V 15A TO3PBL	233
NTE2408 NTE Electronics, Inc.	TRANS NPN 65V 100MA SOT23	1572
NTE2325 NTE Electronics, Inc.	TRANS NPN 800V 3A TO220	55
NTE123A-10 NTE Electronics, Inc.	TRANS NPN 40V 800MA TO18 10PK	3
NTE187A NTE Electronics, Inc.	TRANS PNP 40V 3A TO202M	15
NTE59 NTE Electronics, Inc.	TRANS PNP 200V 17A 3SIP	304
TIP36B NTE Electronics, Inc.	TRANS PNP 80V 25A TO218	453
NTE104MP NTE Electronics, Inc.	TRANS PNP 35V 10A TO3	15
NTE394 NTE Electronics, Inc.	TRANS NPN 400V 3A TO3PN	694
2N6292 NTE Electronics, Inc.	TRANS NPN 70V 7A TO220AB	15
TIP36A NTE Electronics, Inc.	TRANS PNP 60V 25A TO218	507
2N4912 NTE Electronics, Inc.	TRANS PNP 80V 4A TO66	780
NTE219 NTE Electronics, Inc.	TRANS PNP 60V 15A TO3	412
NTE2322 NTE Electronics, Inc.	TRANS PNP 40V 600MA 14DIP	180
NTE127 NTE Electronics, Inc.	TRANS PNP 320V 10A TO3	12
NTE2315 NTE Electronics, Inc.	TRANS NPN 200V 8A TO220	79
2N5039 NTE Electronics, Inc.	TRANS NPN 75V 20A TO3	8
NTE2649 NTE Electronics, Inc.	TRANS NPN 180V 15A TO3P	363
NTE99 NTE Electronics, Inc.	TRANS NPN 400V 50A TO3	128
NTE240 NTE Electronics, Inc.	TRANS PNP 300V 500MA TO202N	134

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