Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2N3725	SMALL SIGNAL BIPOLAR TRANSISTOR	0
KSB1116AYTA	TRANS PNP 60V 1A TO92-3	233957
APT13003DI-G1 Zetex Semiconductors (Diodes Inc.)	TRANS NPN 450V 1.5A TO251	2396
ZUMT619TA Zetex Semiconductors (Diodes Inc.)	TRANS NPN 50V 1A SC70-3	32869
2N4014 PBFREE Central Semiconductor	TRANS NPN 50V TO-18	0
JANTX2N3735 Roving Networks / Microchip Technology	TRANS NPN 40V 1.5A	0
MJ11022G Sanyo Semiconductor/ON Semiconductor	TRANS NPN DARL 250V 15A TO204	552100
SBSP52T1G Sanyo Semiconductor/ON Semiconductor	TRANS NPN DARL 80V 1A SOT223	370
BUX85	TRANS NPN 450V 2A TO220AB	0
BC846BW/DG/B2115 NXP Semiconductors	SMALL SIGNAL BIPOLAR TRANSISTOR	363000
BCP5310H6327XTSA1 IR (Infineon Technologies)	TRANS PNP 80V 1A SOT223	0
TIP31C PBFREE Central Semiconductor	THROUGH-HOLE TRANSISTOR-BIPOLAR	0
MJE5740G	POWER BIPOLAR TRANSISTOR NPN	804
PZT651T1G Sanyo Semiconductor/ON Semiconductor	TRANS NPN 60V 2A SOT223	3821
2SC6026MFVGR,L3F Toshiba Electronic Devices and Storage Corporation	TRANS NPN 50V 0.15A VESM	49
BCP55-10 Diotec Semiconductor	BJT SOT-223 60V 1000MA	0
NSS1C201MZ4T1G Sanyo Semiconductor/ON Semiconductor	TRANS NPN 100V 2A SOT223-4	3000
ZXTP19020DGTA Zetex Semiconductors (Diodes Inc.)	TRANS PNP 20V 8A SOT223	668159000
BCX53-10/L135 NXP Semiconductors	SMALL SIGNAL BIPOLAR TRANSISTOR	3300
BCP53-10 Diotec Semiconductor	BJT SOT-223 80V 1000MA	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