Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
BC849CLT1G Sanyo Semiconductor/ON Semiconductor	TRANS NPN 30V 100MA SOT23-3	58128
2SC13830S Panasonic	TRANS NPN 25V 1A TO-92L	239
STX83003 STMicroelectronics	TRANS NPN 400V 1A TO-92	0
KSP14TA	TRANS NPN 30V 500MA TO92-3	75251
MJE15029G Sanyo Semiconductor/ON Semiconductor	TRANS PNP 120V 8A TO220AB	3348600
NSS12501UW3T2G Sanyo Semiconductor/ON Semiconductor	TRANS NPN 12V 5A 3-WDFN	2978
PBSS5140U,115 Nexperia	TRANS PNP 40V 1A SOT323	11680
PHPT61006PYX Nexperia	TRANS PNP 100V 6A LFPAK56 PWRSO8	1495
BCP69-25-TP Micro Commercial Components (MCC)	PNP,TRANSISTORS,SOT-223 PACKAGE	0
BC327-040G	TRANS PNP 45V 800MA TO92-3	18500
BD136-16 STMicroelectronics	TRANS PNP 45V 1.5A SOT-32	5243
BCX68-16E6327 IR (Infineon Technologies)	SMALL SIGNAL BIPOLAR TRANSISTOR	2000
BC858B-HF Comchip Technology	TRANS PNP 30V 100MA SOT23	0
KSB1116YBU	TRANS PNP 50V 1A TO92-3	3143
ZXTP25040DFHTA Zetex Semiconductors (Diodes Inc.)	TRANS PNP 40V 3A SOT23-3	0
PDTA114EU/ZL135 Nexperia	SMALL SIGNAL BIPOLAR TRANSISTOR	530000
2SC4617EBHZGTLQ ROHM Semiconductor	2SC4617EBHZG IS BIPOLAR TRANSIST	276
BC557CG	TRANS PNP 45V 100MA TO92-3	144000
2PC4081S,135 Nexperia	TRANS NPN 50V 150MA SOT323	0
BCP69-25E6327 IR (Infineon Technologies)	POWER BIPOLAR TRANSISTOR	3000

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