Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2SB14400RL Panasonic	TRANS PNP 50V 2A MINI-PWR	107
2SC370400L Panasonic	TRANS NPN 10V 0.08A MINI-3P	15
2SC370700L Panasonic	TRANS NPN 7V 0.01A MINI-3	3786
DSA7101R0L Panasonic	TRANS PNP 80V 0.5A MINIP-3	34
2SC39350QL Panasonic	TRANS NPN 10V 0.05A SMINI-3P	1645
DSC300100L Panasonic	TRANS NPN 50V 0.1A SSSMINI3	0
2SD18240SL Panasonic	TRANS NPN 100V 0.02A SMINI3P	2
2SD1819GRL Panasonic	TRANS NPN 50V 0.1A SMINI 3P	1328
2SD241300L Panasonic	TRANS NPN 400V 0.1A MINI PWR	2321
DSC750500L Panasonic	TRANS NPN 20V 3A MINIP3	986
2SD10300RL Panasonic	TRANS NPN 40V 0.05A MINI-3	1173
DSC5A01S0L Panasonic	TRANS NPN 40V 0.05A SMINI3	2933
2SB12210QA Panasonic	TRANS PNP 200V 0.07A TO-92NL	2318
XN09D6100L Panasonic	TRANS PNP 15V 1.5A MINI 6P	3000
2SA216300A Panasonic	TRANS PNP 20V 0.03A ML3-N2	8800
2SC3940AQA Panasonic	TRANS NPN 50V 1A TO-92NL	1205
DSC7101S0L Panasonic	TRANS NPN 80V 0.5A MINIP3	87
2SC39400RA Panasonic	TRANS NPN 25V 1A TO-92NL	2120
2SA20670QA Panasonic	TRANS PNP 60V 3A MT-4	1901
DSC550100L Panasonic	TRANS NPN 20V 0.5A SMINI3	2734

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