Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
MPSA63 PBFREE Central Semiconductor	TRANS PNP DARL 20V 0.5A TO-92	13004
2N6388G Sanyo Semiconductor/ON Semiconductor	TRANS NPN DARL 80V 10A TO220AB	247
PBSS4140V,115 NXP Semiconductors	PBSS4140V - 1A, 40V, NPN, SOT6	35960
ZTX788ASTZ Zetex Semiconductors (Diodes Inc.)	TRANS PNP 15V 3A E-LINE	0
BUL705 STMicroelectronics	TRANS NPN 400V 5A TO-220	0
QST6TR ROHM Semiconductor	TRANS PNP 12V 2A TSMT6	0
KSC1008OBU-ON	0.7A, 60V, NPN, TO-92	0
2N6059 NTE Electronics, Inc.	TRANS NPN 100V 12A TO3	116
2SC6011 Sanken Electric Co., Ltd.	TRANS NPN 200V 15A TO3P	965
NTE123A-5 NTE Electronics, Inc.	TRANS NPN 40V 800MA TO18 5PK	19
2SC3468F-AE	SMALL SIGNAL BIPOLAR TRANSTR NPN	67500
2SC5865TLR ROHM Semiconductor	TRANS NPN 60V 1A TSMD3	0
BC848BHZGT116 ROHM Semiconductor	NPN GENERAL PURPOSE TRANSISTOR	960
MPSA13RLRPG	TRANS NPN 30V 500MA TO92-3	0
2SB1275TLP ROHM Semiconductor	TRANS PNP 160V 1.5A SOT-428	2500
PZT2222A,135 Nexperia	TRANS NPN 40V 0.6A SOT223	48196
2SA2126-H Sanyo Semiconductor/ON Semiconductor	TRANS PNP 50V 3A TP	119216500
BC53-16PASX Nexperia	BC53PAS - 80V, 1 A PNP MEDIUM PO	3000
2SA1524	SMALL SIGNAL BIPOLAR TRANS PNP	36800
BD676G Sanyo Semiconductor/ON Semiconductor	TRANS PNP DARL 45V 4A TO225AA	14963000

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