Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2PB709BSL,215 Nexperia	TRANS PNP 50V 200MA TO236AB	0
NJW3281G Sanyo Semiconductor/ON Semiconductor	TRANS NPN 250V 15A TO-3P	45469240
BCP49H6327XTSA1 IR (Infineon Technologies)	TRANS NPN DARL 60V 0.5A SOT223	0
BC850A Diotec Semiconductor	BJT SOT-23 45V 100MA	0
NTE2699 NTE Electronics, Inc.	T-NPN SIL 100V 15A TO220F	390
LS3550SB SOT-23 3L Linear Integrated Systems, Inc.	HIGHER CURRENT SINGLE PNP TRANS	100
BCX42E6327HTSA1 IR (Infineon Technologies)	TRANS PNP 125V 0.8A SOT-23	1472
NZT6726	TRANS PNP 30V 1.5A SOT223-4	2500
MMBT2222	TRANS NPN 30V 600MA SOT23-3	109480
BC858CWH6327XTSA1 IR (Infineon Technologies)	TRANS PNP 30V 100MA SOT323-3	63000
MPS2222ARLRMG	TRANS NPN 40V 600MA TO92-3	38000
NJVMJD47T4G Sanyo Semiconductor/ON Semiconductor	TRANS NPN 250V 1A DPAK-4	1756
2SA1962RTU	POWER BIPOLAR TRANSISTOR, 17A, 2	3987
DCP69-16-13 Zetex Semiconductors (Diodes Inc.)	TRANS PNP 20V 1A SOT-223	61537500
BCP54-16E6433 IR (Infineon Technologies)	POWER BIPOLAR TRANSISTOR	4000
BC327-25BK Diotec Semiconductor	BJT TO-92BK 45V 800MA	30000
PBHV9560ZX Nexperia	IC TRANS PNP 600V 0.5A SOT223	5380
2SB1386T100Q ROHM Semiconductor	TRANS PNP 20V 5A SOT-89	3393
CJD50 TR13 PBFREE Central Semiconductor	TRANS NPN 500A 1A DPAK	0
NSS40400CF8T1G	SMALL SIGNAL BIPOLAR TRANSISTOR	6000

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