Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
2SD1733TLP ROHM Semiconductor	TRANS NPN 80V 1A SOT-428	0
BSR18A	SMALL SIGNAL BIPOLAR TRANSISTOR,	48000
JANTX2N3019S	SMALL SIGNAL BIPOLAR TRANSISTOR	0
TSC966CW RPG TSC (Taiwan Semiconductor)	TRANSISTOR, NPN, 400V, 0.3A, 100	10490
2SC3864	SMALL SIGNAL BIPOLAR TRANSTR NPN	0
MPS751ZL1	TRANS PNP 60V 2A TO92-3	56412
BC847CT116 ROHM Semiconductor	TRANS NPN 45V 0.1A SST3	0
BC550ABU	TRANS NPN 45V 100MA TO92-3	39975
CMPTA92 TR Central Semiconductor	TRANS PNP 300V 0.5A SOT-23	15651
2SB1216S-TL-E Sanyo Semiconductor/ON Semiconductor	TRANS PNP 100V 4A TPFA	1863
BCP55-16F Nexperia	TRANS NPN 60V 1A SOT223	0
2SC5888	TRANS NPN 50V 10A TO220ML	0
2N6297 Roving Networks / Microchip Technology	PNP TRANSISTOR	0
BCW66HTA Zetex Semiconductors (Diodes Inc.)	TRANS NPN 45V 0.8A SOT23-3	2147483647
BC556BBK Diotec Semiconductor	BJT TO-92BK 65V 100MA	245000
ZXTN08400BFFTA Zetex Semiconductors (Diodes Inc.)	TRANS NPN 400V 0.5A SOT23F-3	55654
2SAR553RTL ROHM Semiconductor	TRANS PNP 50V 2A TSMT3	1535
2SC5103TLQ ROHM Semiconductor	TRANS NPN 60V 5A SOT-428	0
DSC200200L Panasonic	TRANS NPN 50V 0.5A MINI3	572
BC337A	TRANS NPN 45V 800MA TO92-3	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