Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
DSC7102R0L Panasonic	TRANS NPN 80V 1A MINIP3	210
2SB09490Q Panasonic	TRANS PNP DARL 60V 2A TO-220F	27
DSC9G02D0L Panasonic	TRANS NPN 30V 0.015A SSMINI3	0
2SD1819AQL Panasonic	TRANS NPN 50V 0.1A SMINI 3P	1900
2SC6054J0L Panasonic	TRANS NPN 50V 0.1A SSMINI-3	4456
DSA7504Q0L Panasonic	TRANS PNP 20V 4A MINIP3	1590
DSA2401S0L Panasonic	TRANS PNP 10V 0.5A MINI3	791
2SA1096AQ Panasonic	TRANS PNP 60V 2A TO-126	0
2SA204600L Panasonic	TRANS PNP 20V 1.5A MINI 3P	5000
2SC39360CL Panasonic	TRANS NPN 20V 0.03A SMINI-3	1733
2SD2345JSL Panasonic	TRANS NPN 40V 0.05A SSMINI-3	2920
2SD21840RA Panasonic	TRANS NPN 150V 1A MT-2	52
2SD19790SL Panasonic	TRANS NPN 20V 0.3A SMINI-3P	19
DSA700400L Panasonic	TRANS PNP 50V 2A MINIP3	688
2SB08730Q Panasonic	TRANS PNP 20V 5A TO-92L	0
2SB15990RL Panasonic	TRANS PNP 40V 1.5A MINI PWR	1414
DSA9001S0L Panasonic	TRANS PNP 50V 0.1A SSMINI3	1451
2SA207800L Panasonic	TRANS PNP 50V 0.1A SSSMINI	1
2SD18210RL Panasonic	TRANS NPN 150V 0.05A SMINI-3	2968
2SB13980QA Panasonic	TRANS PNP 25V 5A MT-2	4854

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