Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2SD1664T100R ROHM Semiconductor	TRANS NPN 32V 1A SOT-89	0
2SA1797T100Q ROHM Semiconductor	TRANS PNP 50V 2A SOT-89	179
2SCR372PT100R ROHM Semiconductor	TRANS NPN 120V 0.7A MPT3	0
2SCR522UBTL ROHM Semiconductor	TRANS NPN 20V 0.2A UMT3F	2943
2SB1182TLQ ROHM Semiconductor	TRANS PNP 32V 2A SOT-428	4260
2SC5876U3HZGT106Q ROHM Semiconductor	2SC5876U3HZG IS THE HIGH SPEED S	2155
2SC5659T2LN ROHM Semiconductor	TRANS NPN 25V 0.05A VMT3	0
2SC5662T2LP ROHM Semiconductor	TRANS NPN 11V 0.05A VMT3	909028
SST2222AHZGT116 ROHM Semiconductor	NPN MEDIUM POWER TRANSISTOR (SWI	1862
2SD1757KT146R ROHM Semiconductor	TRANS NPN 15V 0.5A SOT-346	1687
2SA2029FHAT2LR ROHM Semiconductor	PNP GENERAL PURPOSE AMPLIFICATIO	8000
2SB1188T100P ROHM Semiconductor	TRANS PNP 32V 2A SOT-89	0
2SC4081U3T106Q ROHM Semiconductor	GENERAL PURPOSE SMALL SIGNAL AMP	15
SSTA56T116 ROHM Semiconductor	TRANS PNP 80V 0.5A SST3	5117
2SAR533PFRAT100 ROHM Semiconductor	PNP DRIVER TRANSISTOR (CORRESPON	939
2SAR523MT2L ROHM Semiconductor	TRANS PNP 50V 0.1A VMT3	5271
2SB1474TL ROHM Semiconductor	TRANS PNP DARL 80V 4A SOT-428	0
2SD2674TL ROHM Semiconductor	TRANS NPN 12V 1.5A TSMT3	0
2SC4081T106S ROHM Semiconductor	TRANS NPN 50V 0.15A SOT-323	38
MMSTA06T146 ROHM Semiconductor	TRANS NPN 80V 0.5A SOT-346	9005

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