Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2SA2029T2LR ROHM Semiconductor	TRANS PNP 50V 0.15A VMT3	471
FZT558TA Zetex Semiconductors (Diodes Inc.)	TRANS PNP 400V 0.2A SOT223	26700
JANTX2N2905A Roving Networks / Microchip Technology	TRANS PNP 60V 0.6A	0
BCP5610TA Zetex Semiconductors (Diodes Inc.)	TRANS NPN 80V 1A SOT223	2147483647
2N5191G Sanyo Semiconductor/ON Semiconductor	TRANS NPN 60V 4A TO225AA	190634000
TIP117 TIN/LEAD Central Semiconductor	TRANS PN P 100V TO220	0
TIP111G Sanyo Semiconductor/ON Semiconductor	TRANS NPN DARL 80V 2A TO-220AB	733
NSS12601CF8T1G	SMALL SIGNAL BIPOLAR TRANSISTOR,	65353
PN2907ATA Sanyo Semiconductor/ON Semiconductor	TRANS PNP 60V 800MA TO92-3	1338
BCW30,215 Nexperia	TRANS PNP 32V 100MA TO236AB	895
SMBTA14E6327HTSA1872 IR (Infineon Technologies)	TRANSISTOR DARLINGTON NPN 30V	5000
CMPTA29 TR PBFREE Central Semiconductor	TRANS NPN DARL 100V 0.5A SOT23	37113
BC549BBU	TRANS NPN 30V 100MA TO92-3	5153
JANTX2N3442 Roving Networks / Microchip Technology	TRANS NPN 140V 10A TO-3	0
2SA10220CL Panasonic	TRANS PNP 20V 0.03A MINI-3P	3855
PDTD113EU115 NXP Semiconductors	SMALL SIGNAL BIPOLAR TRANSISTOR	39000
JAN2N2605 Roving Networks / Microchip Technology	TRANS PNP 60V 0.03A TO46	0
BC817K25WH6327XTSA1 IR (Infineon Technologies)	TRANS NPN 45V 500MA SOT323-3	45000
TIP41C-BP Micro Commercial Components (MCC)	TRANS NPN 100V 6A TO-220	0
SBC848BLT1	SMALL SIGNAL BIPOLAR TRANSISTOR	0

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