Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
BC546CTA Sanyo Semiconductor/ON Semiconductor	TRANS NPN 65V 0.1A TO-92	8468
NSS20300MR6T1G	POWER BIPOLAR TRANSISTOR, 3A, 20	174000
PBHV9050Z,115 Nexperia	TRANS PNP 500V 250MA SOT223	370
2STBN15D100 STMicroelectronics	TRANS NPN DARL 100V 12A D2PAK	4231
2SA1419S-TD-H	TRANS PNP 160V 1.5A PCP	0
NTE398 NTE Electronics, Inc.	TRANS PNP 150V 2A TO220	610
MMBT2369LT1	TRANS NPN 15V 200MA SOT23-3	61000
BC32725TF	TRANS PNP 45V 800MA TO92-3	25059
BCP56-10TF Nexperia	TRANS NPN 80V 1A SOT223	1893
BU323Z	TRANS NPN 350V 10A SOT93	0
MMBT3904LT1 IR (Infineon Technologies)	TRANS NPN 40V 200MA SOT23-3	0
MMBT3904-TP Micro Commercial Components (MCC)	TRANS NPN 40V 0.2A SOT23	962387
2SA2060(TE12L,F) Toshiba Electronic Devices and Storage Corporation	TRANS PNP 50V 2A SC-62	0
PBSS4360XX Nexperia	PBSS4360X/SOT89/MPT3	667
BCR119WH6327 IR (Infineon Technologies)	BIPOLAR DIGITAL TRANSISTOR	108000
BC847CTT1G	TRANS NPN 45V 100MA SC75	17673
BC549BBK Diotec Semiconductor	BJT TO-92BK 30V 100MA	0
2N3743 Roving Networks / Microchip Technology	PNP TRANSISTOR	0
BCP69-16/S500115 NXP Semiconductors	SMALL SIGNAL BIPOLAR TRANSISTOR	7000
CMST3906 TR PBFREE Central Semiconductor	TRANS PNP 40V 0.2A SOT323	10865

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