Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
DSA2G01B0L Panasonic	TRANS PNP 20V 0.03A MINI3	0
JANTXV2N3019S Roving Networks / Microchip Technology	TRANS NPN 80V 1A	0
2SA17670QA Panasonic	TRANS PNP 300V 0.07A TO-92	2100
2SA1507T	POWER BIPOLAR TRANSISTOR	4953
2SC6036G0L Panasonic	TRANS NPN 12V 0.5A SSSMINI-3	14328
DSS4160V-7 Zetex Semiconductors (Diodes Inc.)	TRANS NPN 60V 1A SOT-563	3750
2PB709ASW,115 NXP Semiconductors	NOW NEXPERIA 2PB709ASW - SMALL S	323217
2SA1827S-AY Sanyo Denki SanUPS Products	PNP SILICON TRANSISTOR	0
BC846B-7-F Zetex Semiconductors (Diodes Inc.)	TRANS NPN 65V 0.1A SOT23-3	125727
LS3550SC SOT-23 3L Linear Integrated Systems, Inc.	HIGHER CURRENT SINGLE PNP TRANS	100
BC847CW-AQ Diotec Semiconductor	BJT SOT-323 45V 100MA	0
KSC2310YTA	TRANS NPN 150V 50MA TO92-3	14000
2N3637UB Roving Networks / Microchip Technology	TRANS PNP 175V 1A 3PIN SMD	0
2N4923 NTE Electronics, Inc.	TRANS NPN 80V 1A TO225AA	48
BC847B-E6327 IR (Infineon Technologies)	BIPOLAR GEN PURPOSE TRANSISTOR	36000
BC846AW Diotec Semiconductor	BJT SOT-323 65V 100MA	0
2N3906RL1G	TRANS PNP 40V 200MA TO92-3	127000
PMBT5551,235 Nexperia	TRANS NPN 160V 0.3A SOT23	0
JANTX2N3700UB Roving Networks / Microchip Technology	TRANS NPN 80V 1A	0
2SAR552PT100 ROHM Semiconductor	TRANS PNP 30V 3A MPT3	860

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