Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2SCR513P5T100 ROHM Semiconductor	NPN 50V 1A MEDIUM POWER TRANSIST	4066
2SC4726TLP ROHM Semiconductor	TRANS NPN 11V 0.05A SOT-416	0
2SC5103TLP ROHM Semiconductor	TRANS NPN 60V 5A SOT-428	0
2SC5824T100R ROHM Semiconductor	TRANS NPN 60V 3A MPT3	4
2SCR372PT100Q ROHM Semiconductor	TRANS NPN 120V 0.7A MPT3	0
2SC3838KT146N ROHM Semiconductor	TRANS NPN 11V 0.05A SOT-346	733
2SAR513PT100 ROHM Semiconductor	TRANS PNP 50V 1A MPT3	318
2SB852KT146B ROHM Semiconductor	TRANS PNP DARL 32V 0.3A SOT-346	61
2SC5663T2L ROHM Semiconductor	TRANS NPN 12V 0.5A VMT3	2996
2SD2114KT146V ROHM Semiconductor	TRANS NPN 20V 0.5A SOT-346	2995
2SB1710TL ROHM Semiconductor	TRANS PNP 30V 1A TSMT3	848
2SCR512P5T100 ROHM Semiconductor	NPN 30V 2A MEDIUM POWER TRANSIST	780
2SB1132T100R ROHM Semiconductor	TRANS PNP 32V 1A SOT-89	905
2SAR573D3TL1 ROHM Semiconductor	POWER TRANSISTOR WITH LOW VCE(SA	2932
2SCR346PT100Q ROHM Semiconductor	NPN 100MA 400V MIDDLE POWER TRAN	19888
2SC4081T106Q ROHM Semiconductor	TRANS NPN 50V 0.15A SOT-323	3524
SSTA06T116 ROHM Semiconductor	TRANS NPN 80V 0.5A SST3	6789
2SA1727TLP ROHM Semiconductor	TRANS PNP 400V 0.5A SOT-428	0
2SD1484KT146Q ROHM Semiconductor	TRANS NPN 50V 0.5A SOT-346	3497
2SB1197KT146R ROHM Semiconductor	TRANS PNP 32V 0.8A SOT-346	2943

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