Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
IGTH20N50A	N-CHANNEL IGBT FOR SWITCHING APP	0
TIP3055 STMicroelectronics	TRANS NPN 60V 15A TO-247	4065
BUX48A NTE Electronics, Inc.	TRANS NPN 450V 15A TO3	406
TIP35B	GENERAL PURPOSE NPN TRANSISTOR	9630
JANTX2N3637L Roving Networks / Microchip Technology	TRANS PNP 175V 1A	0
2N3904TF Sanyo Semiconductor/ON Semiconductor	TRANS NPN 40V 200MA TO92-3	0
ZTX955 Zetex Semiconductors (Diodes Inc.)	TRANS PNP 140V 3A E-LINE	20000
BCX56,115 Nexperia	TRANS NPN 80V 1A SOT89	6215
PBSS302NX,115 Nexperia	TRANS NPN 20V 5.3A SOT89	822
DTC114TE	TRANS PREBIAS NPN 200MW SC75	90000
JAN2N4150 Roving Networks / Microchip Technology	TRANS NPN 70V 10A TO-5	0
MJE350 STMicroelectronics	TRANS PNP 300V 0.5A SOT-32	2180
2SC3399	SMALL SIGNAL BIPOLAR TRANSTR NPN	29270
BCX53-16T100 ROHM Semiconductor	TRANS PNP MPT3	0
MAT04FY Analog Devices, Inc.	MATCHED QUAD TRANSISTOR	13371
2PA1774R,115 NXP Semiconductors	TRANS PNP 50V 150MA SC75	978371
S2SC4617G Sanyo Semiconductor/ON Semiconductor	TRANS NPN 50V 100MA SC75 SOT416	0
BC80716E6327 IR (Infineon Technologies)	BIPOLAR GEN PURPOSE TRANSISTOR	432000
KSH210TF	POWER BIPOLAR TRANSISTOR	165720
NTE29 NTE Electronics, Inc.	TRANS NPN 80V 50A TO3	99

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