Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
BULD741T4 STMicroelectronics	TRANS NPN 400V 2.5A DPAK	6553
MZ0912B50Y Ampleon	RF POWER BIPOLAR TRANSISTOR, 1-E	176
FZT1149ATA Zetex Semiconductors (Diodes Inc.)	TRANS PNP 25V 4A SOT-223	303
PUMB2/L135 NXP Semiconductors	SMALL SIGNAL BIPOLAR TRANSISTOR	340000
PBSS4230QAZ NXP Semiconductors	PBSS4230QA - 30V, 2A NPN LOW VCE	100000
ZXTP25015DFHTA Zetex Semiconductors (Diodes Inc.)	TRANS PNP 15V 4A SOT23-3	1218000
JANTX2N720A Roving Networks / Microchip Technology	TRANS NPN 80V 0.5A TO-18	0
BC817-16W,135 NXP Semiconductors	NOW NEXPERIA BC817-16W - SMALL S	40000
PMBTA44,215 Nexperia	TRANS NPN 400V 0.3A SOT23	68300
CET3904E TR PBFREE Central Semiconductor	TRANS NPN 60V 0.2A SOT883	2147483647
PMST5550,115 Nexperia	TRANS NPN 140V 300MA SOT323	7726
BC847BR13 Diotec Semiconductor	BJT SOT-23 45V 100MA	0
BDV64BG Sanyo Semiconductor/ON Semiconductor	TRANS PNP DARL 100V 10A TO247	104
2SD879	TRANSISTOR	9500
BC848B-7-F Zetex Semiconductors (Diodes Inc.)	TRANS NPN 30V 0.1A SOT23-3	75000
TIP127G Sanyo Semiconductor/ON Semiconductor	TRANS PNP DARL 100V 5A TO220AB	1858
ZXTP5401GTA Zetex Semiconductors (Diodes Inc.)	TRANS PNP 150V 0.6A SOT223	1526217000
TN6727A	SMALL SIGNAL BIPOLAR TRANSISTOR,	0
2SD2620G0L Panasonic	TRANS NPN 100V 0.02A SSMINI-3	473
PBSS4130T,215 Nexperia	TRANS NPN 30V 1A TO236AB	15876

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