Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2SAR587D3TL1 ROHM Semiconductor	PNP -3.0A -120V POWER TRANSISTOR	2385
2SAR543RTL ROHM Semiconductor	TRANS PNP 50V 3A TSMT3	854
2SB1424T100R ROHM Semiconductor	TRANS PNP 20V 3A MPT3	365
QSX6TR ROHM Semiconductor	TRANS NPN 30V 1.5A TSMT6	0
BC817-25T116 ROHM Semiconductor	TRANS NPN 45V 0.8A SST3	0
2SCR375P5T100Q ROHM Semiconductor	NPN 120V 1.5A MEDIUM POWER TRANS	476
BSS63AHZGT116 ROHM Semiconductor	BSS63AHZG IS A SOT-23 PACKAGE TR	2890
BSS5130AHZGT116 ROHM Semiconductor	BSS5130AHZG IS A SOT-23 PACKAGE	2880
2SC5729T106Q ROHM Semiconductor	TRANS NPN 30V 0.5A SC70	0
2SB1412TLP ROHM Semiconductor	TRANS PNP 20V 5A SOT-428	0
SST2907AHZGT116 ROHM Semiconductor	PNP MEDIUM POWER TRANSISTOR (SWI	2563
2SB1260T100P ROHM Semiconductor	TRANS PNP 80V 1A SOT-89	0
2SC4617TLQ ROHM Semiconductor	TRANS NPN 50V 0.15A SOT-416	12
2SB1412TLQ ROHM Semiconductor	TRANS PNP 20V 5A SOT-428	2658
BSS4130AT116 ROHM Semiconductor	TRANS 100V 100A SOT-23	2659
2SB1708TL ROHM Semiconductor	TRANS PNP 30V 3A TSMT 3	4511
2SC2411KT146Q ROHM Semiconductor	TRANS NPN 32V 0.5A SOT-346	0
2SA1576U3T106S ROHM Semiconductor	GENERAL PURPOSE TRANSISTOR (-50V	1068
UMT3906T106 ROHM Semiconductor	TRANS PNP 40V 0.2A SOT-323	1387
MMST3904T146 ROHM Semiconductor	TRANS NPN 40V 0.2A SOT-346	4201

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