Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2N3583 NTE Electronics, Inc.	TRANS NPN 175V 10MA TO66	224
MJE4343 NTE Electronics, Inc.	TRANS NPN 160V 16A SOT93	360
NTE245 NTE Electronics, Inc.	TRANS NPN 80V 10A TO3	1137
2N5496 NTE Electronics, Inc.	TRANS NPN 70V 7A TO220	176
MPSA63 NTE Electronics, Inc.	T-PNP DARLINGTON AMP	1549
TIP140 NTE Electronics, Inc.	T-NPN SI- PO DARLINGTON	538
NTE123AP-5 NTE Electronics, Inc.	TRANS NPN 40V 600MA TO92 5PK	12
NTE102A NTE Electronics, Inc.	TRANS PNP 1A TO1	477
2N5172 NTE Electronics, Inc.	TRANS NPN 25V 500MA TO92-3	24
NTE232 NTE Electronics, Inc.	TRANS PNP 30V 300MA TO92	5850
NTE2685 NTE Electronics, Inc.	TRANS NPN 150V 8A TO3PML	748
NTE2362 NTE Electronics, Inc.	TRANS PNP 50V 500MA TO92S	312
PN4248 NTE Electronics, Inc.	T-PNP SI- LOW LEVEL AMP	2469
NTE2337 NTE Electronics, Inc.	TRANS NPN 500V 7A TO220	516
NTE2347 NTE Electronics, Inc.	TRANS NPN 80V 5A TO39	68
NTE2684 NTE Electronics, Inc.	TRANS NPN 120V 5A TO126	708
NTE2345 NTE Electronics, Inc.	TRANS NPN 120V 6A SOT82	285
MJ11028 NTE Electronics, Inc.	TRANS NPN 60V 50A TO3	602
BUX10 NTE Electronics, Inc.	TRANS NPN 125V 25A TO3	1504
NTE2647 NTE Electronics, Inc.	T-PNP SI PWR AMP 230V 1A TO-220	820

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