Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
BSV52LT1G Sanyo Semiconductor/ON Semiconductor	TRANS NPN 12V 100MA SOT23-3	2147483647
FMMT619-G Comchip Technology	NPN TRANSISTOR 2A 50V SOT-23 ROH	0
MJF45H11G Sanyo Semiconductor/ON Semiconductor	TRANS PNP 80V 10A TO-220FP	15512800
2N5320 NTE Electronics, Inc.	T-NPN SI- SWITCH	130
2SD1620-TD-E Sanyo Semiconductor/ON Semiconductor	TRANS NPN 10V 3A PCP	278811000
FJV1845PMTF	0.05A, 120V, NPN	0
2SC5661T2LP ROHM Semiconductor	TRANS NPN 20V 0.05A VMT3	3563
PBSS2515M3145 NXP Semiconductors	SMALL SIGNAL BIPOLAR TRANSISTOR	0
BC857CW,135 Nexperia	TRANS PNP 45V 0.1A SOT323	0
MJ21194G	POWER BIPOLAR TRANSISTOR, 16A, 2	692
2N3792 PBFREE Central Semiconductor	TRANS PNP 80V 10A TO-3	272
2SA2126-E	TRANS PNP 50V 3A TP	34500
PBSS4330PA,115 Nexperia	TRANS NPN 30V 3A SOT1061	12136
SMMBTA06WT1G Sanyo Semiconductor/ON Semiconductor	TRANS NPN 80V 0.5A SC70-3	1827
2SC2462LCTR-E Renesas Electronics America	SMALL SIGNAL BIPOLAR TRANSISTOR,	3000
KSD471AGTA	1A, 30V, NPN, TO-92	11755
BD675AS	POWER BIPOLAR TRANSISTOR	1719
BC548C B1G TSC (Taiwan Semiconductor)	TRANSISTOR, NPN, 30V, 0.1A, 420A	0
BCW70LT1	TRANS PNP 45V 100MA SOT23-3	5886
KSC5027OTU Sanyo Semiconductor/ON Semiconductor	TRANS NPN 800V 3A TO-220	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