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Transistors - Bipolar (BJT) - Single

Image Part Number Description / PDF Quantity Rfq
FMMT549TA

FMMT549TA

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 30V 1A SOT23-3

0
MMST5401Q-7-F

MMST5401Q-7-F

Zetex Semiconductors (Diodes Inc.)

SS HI VOLTAGE TRANSISTOR SOT323

45000
BC857BFZ-7B

BC857BFZ-7B

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 45V 0.1A X2-DFN060

527110000
MMSTA13-7-F

MMSTA13-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS NPN DARL 30V 0.3A SC70-3

0
BC857CT-7-F

BC857CT-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 45V 0.1A SOT-523

1044
APT13003HZTR-G1

APT13003HZTR-G1

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 465V 1.5A TO92

3018
ZXTN25020DZTA

ZXTN25020DZTA

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 20V 6A SOT89

253
FMMT497TA

FMMT497TA

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 300V 0.5A SOT23-3

0
ZTX795A

ZTX795A

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 140V 0.5A E-LINE

335932000
ZXTN25040DZTA

ZXTN25040DZTA

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 40V 5A SOT-89

5506
2DC4617S-7-F

2DC4617S-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 50V 0.15A SOT523

173178000
FZT651QTA

FZT651QTA

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 60V 3A SOT-223

4512
FCX596TA

FCX596TA

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 200V 0.3A SOT-89

608410000
FMMT589TA

FMMT589TA

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 30V 1A SOT23-3

2147483647
DXT690BP5-13

DXT690BP5-13

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 45V 3A POWERDI5

94920000
FZT657TA

FZT657TA

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 300V 0.5A SOT-223

119157
ZTX718

ZTX718

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 20V 2.5A E-LINE

0
2DC4672-13

2DC4672-13

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 50V 3A SOT89-3

0
BCX5616TA

BCX5616TA

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 80V 1A SOT-89

40531
2DB1689-7

2DB1689-7

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 12V 1.5A SOT-323

112527000

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

TypeFunctional CharacteristicsApplication Examples
NPN TransistorMajority carriers: electrons. Requires positive base current for conduction.Low-noise amplifiers, digital logic circuits
PNP TransistorMajority carriers: holes. Conducts with negative base current.Power supply circuits, motor controllers
High-Frequency BJTOptimized for RF/microwave signal amplification (fT > 100 MHz)Wireless communication systems, radar
Power BJTHigh current/voltage ratings (IC > 1A, VCE > 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

ParameterDescriptionImportance
Current Gain (hFE)Ratio of collector to base current (10-1000)Determines amplification capability
Transition Frequency (fT)Frequency at which current gain drops to 1Limits high-frequency performance
Max Collector Current (ICmax)Maximum allowable continuous collector currentDefines power handling capability
Breakdown Voltage (VCEO)Max voltage between collector and emitterPrevents device failure under stress
Saturation Voltage (VCEsat)Voltage drop in fully conducting stateAffects 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

ManufacturerProduct SeriesKey SpecificationsTypical Use
ON Semiconductor2N3904hFE: 100-300, fT: 300 MHzGeneral-purpose switching
InfineonBC547VCEO: 50V, ICmax: 100mAAnalog signal amplification
STMicroelectronics2SD2656ICmax: 15A, VCEO: 80VPower inverter applications
Diodes Inc.BFR93AfT: 10 GHz, Noise Figure: 2dBHigh-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=VCE IC)
  • 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
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