Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2SD2138APA Panasonic	TRANS NPN DARL 80V 2A MT-4	1509
DSC250100L Panasonic	TRANS NPN 20V 0.5A MINI3	1622
2SC3526H Panasonic	TRANS NPN 50V 0.15A TO-92L	116
2SD225900A Panasonic	TRANS NPN 20V 0.7A MT-2	2857
DSC9A01R0L Panasonic	TRANS NPN 40V 0.05A SSMINI3	1976
DSA7004S0L Panasonic	TRANS PNP 50V 2A MINIP3-F	3977
2SC555600L Panasonic	TRANS NPN 10V 0.08A MINI-3	5010
DSA7003S0L Panasonic	TRANS PNP 50V 1A MINIP3	668
DSA300100L Panasonic	TRANS PNP 50V 0.1A SSSMINI3	8158
DSA7102R0L Panasonic	TRANS PNP 80V 1A MINIP3	562
DSA5001R0L Panasonic	TRANS PNP 50V 0.1A SMINI3	0
2SB14880PA Panasonic	TRANS PNP 400V 0.5A MT-2	3450
DSA7003R0L Panasonic	TRANS PNP 50V 1A MINIP3	39
DSC7101R0L Panasonic	TRANS NPN 80V 0.5A MINIP3	0
2SD09660Q Panasonic	TRANS NPN 20V 5A TO-92L	149
2SC39290RL Panasonic	TRANS NPN 35V 0.05A SMINI-3	2924
2SC13830R Panasonic	TRANS NPN 25V 1A TO-92L	318
DSC2G02D0L Panasonic	TRANS NPN 20V 0.015A MINI3	0
2SC57880PA Panasonic	TRANS NPN 60V 3A MT-4	1181
DSC2002R0L Panasonic	TRANS NPN 50V 0.5A MINI3	1

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