Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
D72F5T2	NPN DARLINGTON POWER TRANSISTOR	159841
15C01C-TB-E	SMALL SIGNAL BIPOLAR TRANSISTOR	117000
FJX733YTF	0.15A, 50V, PNP	106114
KSC2688YS	TRANS NPN 300V 200MA TO126	0
2SC6095-TD-E Sanyo Semiconductor/ON Semiconductor	TRANS NPN 80V 2.5A PCP	3087
BCX56-16T100 ROHM Semiconductor	TRANS NPN 80V 1A MPT3	0
BC848CDXV6T1	SMALL SIGNAL BIPOLAR TRANSISTOR	28000
BC337-25 A1G TSC (Taiwan Semiconductor)	TRANSISTOR, NPN, 45V, 0.8A, 160A	0
BC327	SMALL SIGNAL BIPOLAR TRANSISTOR	52356
2SD23210RA Panasonic	TRANS NPN 20V 5A NS-B1	4605
MJD112RLG Sanyo Semiconductor/ON Semiconductor	TRANS NPN DARL 100V 2A DPAK	135
NTE152 NTE Electronics, Inc.	TRANS NPN 90V 4A TO220	316
BDC01DRL1	SMALL SIGNAL BIPOLAR TRANSISTOR	10000
2SA1593T-TL-E Sanyo Semiconductor/ON Semiconductor	TRANS PNP 100V 2A TP-FA	9553500
2SD22420PA Panasonic	TRANS NPN DARL 60V 4A MT-4	900
NST857BF3T5G	SMALL SIGNAL BIPOLAR TRANSISTOR,	824000
2SD1815T-TL-E	SMALL SIGNAL BIPOLAR TRANSISTOR,	32190
MPSA05 NTE Electronics, Inc.	SMALL SIGNAL BIPOLAR TRANSISTOR	16813
2SB1588 Sanken Electric Co., Ltd.	TRANS PNP DARL 150V 10A TO3PF	0
2SC4706 Sanken Electric Co., Ltd.	TRANS NPN 600V 14A TO3P	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