Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2SC5876T106Q ROHM Semiconductor	TRANS NPN 60V 0.5A SOT-323	4379
SST4401T116 ROHM Semiconductor	TRANS NPN 40V 0.6A SST3	271
2SA2092TLQ ROHM Semiconductor	TRANS PNP 60V 1A TSMD3	0
SSTA56HZGT116 ROHM Semiconductor	PNP GENERAL PURPOSE TRANSISTOR	315
2SCR533PFRAT100 ROHM Semiconductor	NPN DRIVER TRANSISTOR (CORRESPON	358
2SA2071P5T100Q ROHM Semiconductor	60V 3A POWER TRANSISTOR FOR HIGH	181
2SCR514PT100 ROHM Semiconductor	TRANS NPN 80V 0.7A SOT-89	675
US6T4TR ROHM Semiconductor	TRANS PNP 12V 3A TUMT6	0
BCX19T116 ROHM Semiconductor	TRANS NPN 45V 0.5A SST3	5793
2SCR502U3HZGT106 ROHM Semiconductor	2SCR502U3HZG IS THE GENERAL PURP	2634
2SA2088T106Q ROHM Semiconductor	TRANS PNP 60V 0.5A SOT-323 TR	0
2SD1766T100P ROHM Semiconductor	TRANS NPN 32V 2A SOT-89	0
2SC3906KT146S ROHM Semiconductor	TRANS NPN 120V 0.05A SOT-346	2830
2SD1781KT146R ROHM Semiconductor	TRANS NPN 32V 0.8A SOT-346	1906
2SCR552PFRAT100 ROHM Semiconductor	NPN DRIVER TRANSISTOR (CORRESPON	718
2SB1308T100Q ROHM Semiconductor	TRANS PNP 20V 3A SOT-89	0
US6X6TR ROHM Semiconductor	TRANS NPN 30V 1.5A TUMT6	0
BSS5130AT116 ROHM Semiconductor	TRANS 100V 100A SOT-23	2685
2SD1758TLQ ROHM Semiconductor	TRANS NPN 32V 2A SOT-428	0
2SCR522MT2L ROHM Semiconductor	TRANS NPN 20V 0.2A VMT3	5331

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