Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
ZXTP19060CZTA Zetex Semiconductors (Diodes Inc.)	TRANS PNP 60V 4.5A SOT89	99644000
BCV27E6327HTSA1 IR (Infineon Technologies)	TRANS NPN DARL 30V 0.5A SOT-23	0
BCW61CE6327HTSA1 IR (Infineon Technologies)	TRANS PNP 32V 100MA SOT23-3	6622
2N3904 NTE Electronics, Inc.	T-NPN SI-GEN PUR AMP SW	6643
NTE2321 NTE Electronics, Inc.	TRANS NPN 40V 500MA 14DIP	341
BC848AE6327HTSA1 IR (Infineon Technologies)	TRANS NPN 30V 100MA SOT23-3	354000
D40K2 NTE Electronics, Inc.	T-NPN SI DARLINGTON	536
PZT2222AT1	TRANS NPN 40V 600MA SOT223	0
2N5550/D26Z	NPN EPITAXIAL SILICON TRANSISTOR	24000
2SD896D	POWER BIPOLAR TRANSISTOR NPN	7041
FJP5554TU	POWER BIPOLAR TRANSISTOR	7651
PBSS306PX,115 Nexperia	TRANS PNP 100V 3.7A SOT89	514
2SC3519A Sanken Electric Co., Ltd.	TRANS NPN 180V 15A TO-3P	0
FJX945GTF	0.15A, 50V, NPN	88166
SMBT3906	SMALL SIGNAL BIPOLAR TRANSISTOR	6000
BD680AS	POWER BIPOLAR TRANSISTOR, 4A I(C	1996
MPSW06	SMALL SIGNAL BIPOLAR TRANSISTOR	41000
2N3906RLRPG	TRANS PNP 40V 200MA TO92-3	0
2SCR542F3TR ROHM Semiconductor	NPN 3.0A 30V MIDDLE POWER TRANSI	2961
KSD1616GTA	TRANS NPN 50V 1A TO92-3	4000

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