Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2SA216400L Panasonic	TRANS PNP 20V 0.03A SSSMINI3P	17963
2SD19960SA Panasonic	TRANS NPN 20V 0.5A MT-1	3819
2SB1218ARL Panasonic	TRANS PNP 45V 0.1A SMINI 3P	10390
2SC565400L Panasonic	TRANS NPN 20V 1A SMINI-3	5888
2SC57250SL Panasonic	TRANS NPN 15V 2A MINI 3P	7794
2SB13980PA Panasonic	TRANS PNP 25V 5A MT-2	3330
2SB1417APA Panasonic	TRANS PNP 80V 3A MT-4	1204
2SA0963 Panasonic	TRANS PNP 40V 1.5A TO-126	52
DSA2001S0L Panasonic	TRANS PNP 50V 0.1A MINI3	5844
DSC7Q01R0L Panasonic	TRANS NPN DARL 80V 1A MINIP3	542
2SD235800A Panasonic	TRANS NPN 10V 1A MT-2	3410
2SD19960TA Panasonic	TRANS NPN 20V 0.5A MT-1	3885
DSC2A01R0L Panasonic	TRANS NPN 40V 0.05A MINI3	1432
DSA2401R0L Panasonic	TRANS PNP 10V 0.5A MINI3	1629
2SB07790RL Panasonic	TRANS PNP 20V 0.5A MINI-3	2990
2SD12950RL Panasonic	TRANS NPN 40V 1.5A U-G2	2762
2SB07740RA Panasonic	TRANS PNP 25V 0.1A TO-92	8118
DSC9A01T0L Panasonic	TRANS NPN 40V 0.05A SSMINI3	1248
2SC6037J0L Panasonic	TRANS NPN 12V 0.5A SSMINI-3	6514
DSA340200L Panasonic	TRANS PNP 12V 0.5A SSSMINI3	7257

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